Section 1: Introduction

1.1 Why a Caribbean-Specific Reference Matters

Most clinical decision support tools were built somewhere else.

The big international references — Lexicomp, Micromedex, Medscape, the BNF — are excellent. They are also, almost without exception, written for prescribers working in the United States, the United Kingdom, or continental Europe. Their formularies reflect what is available in those markets. Their interaction warnings are calibrated against the medicines those clinicians actually prescribe. Their elderly-care guidance assumes a patient population whose comorbidity profile, polypharmacy patterns, and social context look very different from what we see in clinic in Kingston, Port of Spain, or Castries.

Caribbean prescribing draws on a different reality. Our formularies are shaped by procurement constraints, regional disease burden, historical prescribing tradition, and the practical question of what is actually on the pharmacy shelf this week. A senior pharmacist working in Jamaica or the OECS knows that the medicines clinicians reach for first are not always the medicines the international references treat as the standard of care. Sometimes the differences are minor. Sometimes they matter clinically.

This report is an attempt to close part of that gap.

1.2 What This Report Covers

The Caribbean Essential Medicines Atlas is, at its core, a safety map. It takes the medicines that appear on the three principal Caribbean essential medicines lists — the Jamaica Vital, Essential and Necessary Medicines List; the Trinidad and Tobago Essential Drugs List; and the OECS Pharmaceutical Procurement Service Essential Medicines List — and maps them against six dimensions of clinical safety:

• Drug interactions of major or contraindicated severity
• The AGS Beers Criteria 2023, which flags medicines inappropriate for adults aged 65 and over
• Anticholinergic burden, scored using the published ACB scale
• Therapeutic duplications, the patterns where the same therapeutic effect is unintentionally prescribed twice
• Prescribing cascades, where the side effect of one medicine is misread as a new condition and treated with a second
• Organ function flags, for medicines requiring dose adjustment in renal or hepatic impairment

The interactions discussed in Section 3 are organised into eight clinical themes — from warfarin–antibiotic combinations to live vaccines in immunosuppression — chosen because they are clinically significant, well-documented in the international literature, and involve medicines that Caribbean clinicians actually prescribe. The Beers crossover in Section 4 draws on the most current AGS criteria and identifies which Caribbean essential medicines fall into each Beers category. The cascades in Section 7 are selected from a wider catalogue of 48 documented patterns, with preference given to those most likely to occur in regional practice.

This is not a complete pharmacology reference, and it does not try to be one. It is a safety atlas — the medications that matter, the risks worth knowing about, and the practical decisions clinicians make at the point of care.

1.3 How to Use This Report

Treat this report as a desk reference, not a textbook.

Each section is self-contained. You can read it cover to cover, but most clinicians will use it the way they use any clinical reference: jump to what they need, find the answer, get back to the patient. The interaction summaries in Section 3 are structured identically — drug pair, severity, mechanism, clinical risk, management, reference — so that once you know one, you know them all. The Beers spotlight in Section 4 follows the same pattern. The cascades in Section 7 are presented as flow diagrams you can read at a glance.

The report deliberately repeats certain key concepts across sections. The "triple whammy" of ACE inhibitor, NSAID, and diuretic appears in the interaction section, the cascade section, and the organ function discussion — because clinicians encounter it through all three lenses, and each lens reveals something the others do not.

A note on terminology. Where this report refers to "the Caribbean" it means, specifically, the territories served by the three reference lists above: Jamaica, Trinidad and Tobago, and the OECS member states (Antigua and Barbuda, Dominica, Grenada, Montserrat, St Kitts and Nevis, St Lucia, and St Vincent and the Grenadines). The findings will be broadly relevant to other Caribbean territories, but the data here is drawn from these three lists specifically.

1.4 A Note on Methodology

The data in this report is drawn from authoritative public sources, most of them in the public domain. Interactions and prescribing information were verified against DailyMed (the US National Library of Medicine's product labelling resource), LiverTox (the NIH's hepatotoxicity reference), the European Medicines Agency, and Health Canada's drug product database. The Beers Criteria material is drawn from the American Geriatrics Society's 2023 update. Anticholinergic burden scores are taken from the published ACB scale. A fuller methodology, including the data extraction approach, appears in Section 10.

The interaction text in this report is original work. It has not been reproduced verbatim from any source. Where specific clinical guidance is drawn from a particular reference, that reference is cited inline.

1.5 A Last Word Before We Begin

Clinical decision support is exactly that: support. It cannot replace the judgment of a clinician who knows the patient, the history, and the circumstances. Every alert in this report — and every alert in the Eles Rx tool that automates them — should be interpreted in the context of the individual patient. The risks described here are real, but they are also manageable. Most of the time, the right action is not to avoid a medicine altogether but to use it with awareness of what could go wrong.

That awareness is what this report is for.

Section 2: The Three Caribbean Essential Medicines Lists

2.1 What an Essential Medicines List Actually Is

Before we look at the three Caribbean lists individually, it is worth pausing on what an essential medicines list is, and what it is not.

An essential medicines list is, at its simplest, a national or regional formulary of medicines considered necessary for the basic health needs of the population. The concept originates with the World Health Organization, which has maintained a model Essential Medicines List since 1977 and revises it every two years. National lists are typically derived from the WHO model, then adapted to local disease burden, available healthcare infrastructure, procurement capacity, and clinical tradition.

What an essential medicines list is not is a complete reference of what clinicians may prescribe. Medicines outside the list are still prescribed, still imported, still dispensed. The list is a statement of priority — these are the medicines the system commits to making available, procuring efficiently, and ensuring quality control over. Clinicians work with the list as a framework, not a constraint.

The Caribbean has three principal essential medicines lists in active use. They overlap significantly, but each was developed for a slightly different purpose, and the differences are worth understanding.

2.2 The Jamaica Vital, Essential and Necessary Medicines List

Jamaica maintains its national formulary under the framework of the Vital, Essential and Necessary (VEN) system — a tiered classification developed by the World Health Organization to help low- and middle-income countries prioritise medicines under budget constraints.

The three tiers carry specific operational meanings:

• Vital (V) medicines are those without which a life-threatening situation cannot be managed. These are non-negotiable. If procurement budgets are constrained, vital medicines must still be available.
• Essential (E) medicines are effective in treating common diseases but are not immediately life-saving. They form the backbone of routine clinical care.
• Necessary (N) medicines treat less severe illnesses or are of secondary utility. They are procured when budgets allow.

The current Jamaica VEN list is published by the Ministry of Health and Wellness and informs both public-sector procurement and the clinical curricula of Jamaican prescribers. The list covers several hundred medicines across all major therapeutic categories and is revised periodically to reflect changes in disease burden, treatment guidelines, and procurement realities.

For the purposes of this atlas, the VEN tier is less important than inclusion on the list itself. A medicine is on the Jamaica list, or it is not. Where tier-specific safety considerations apply, this is noted in the relevant section.

2.3 The Trinidad and Tobago Essential Drugs List

Trinidad and Tobago maintains a separate Essential Drugs List under the Ministry of Health. The structure is broader than the VEN tiering — medicines are classified primarily by therapeutic category and level of care (primary, secondary, tertiary), reflecting Trinidad and Tobago's larger and more stratified public health system.

The Trinidad and Tobago list is comprehensive, covering several hundred medicines across all major therapeutic categories, and is notable for its detail around level-of-care designations. A medicine designated for tertiary use only is not stocked in primary care clinics; this has practical implications for what general practitioners can prescribe locally without referral.

For this atlas, the level-of-care distinction is not a primary concern — clinical safety risks are present whether a medicine is prescribed in a primary clinic or a tertiary hospital. But where a Caribbean clinician might encounter a particular medicine only in a specialist setting, it is noted.

2.4 The OECS Essential Medicines List

The Organisation of Eastern Caribbean States operates a shared pharmaceutical procurement service, the OECS Pharmaceutical Procurement Service (OECS-PPS), which negotiates bulk purchasing of medicines on behalf of its member states. The OECS Essential Medicines List is, accordingly, a procurement document as much as a clinical one.

The list covers the seven OECS member states: Antigua and Barbuda, Dominica, Grenada, Montserrat, St Kitts and Nevis, St Lucia, and St Vincent and the Grenadines.

Because the OECS list is built around shared procurement, it tends to be slightly leaner than the Jamaica or Trinidad and Tobago lists — focusing on medicines where bulk purchasing yields significant cost savings and where supply chains can be reliably maintained across multiple small island states. Some specialist medicines available in Jamaica or Trinidad through individual procurement do not appear on the OECS list.

For clinicians practising in the OECS member states, the list defines the realistic clinical formulary far more directly than in Jamaica or Trinidad and Tobago, because procurement and prescribing are more tightly coupled.

2.5 The Overlap and the Gaps

The three lists overlap substantially, which is unsurprising. The medicines that treat the major causes of Caribbean morbidity — hypertension, diabetes, asthma, common infections, mental health conditions, and the chronic non-communicable diseases — appear on all three. The WHO Model List of Essential Medicines forms the common foundation.

The differences begin at the margins. A handful of newer medicines may appear on one list but not yet on another. Procurement preferences differ — Jamaica may prefer a particular generic that the OECS list does not stock. Older medicines retained in one country's prescribing tradition may have been removed from another's list entirely.

For the purposes of this atlas, a medicine is included in the analysis if it appears on at least one of the three reference lists. This is a deliberately inclusive criterion. A clinician working anywhere in the region is likely to encounter the medicine in question, even if the local essential medicines list does not formally include it.

2.6 A Working Definition for This Report

For clarity, when this atlas refers to a "Caribbean essential medicine," it means a medicine appearing on at least one of:

• The Jamaica Vital, Essential and Necessary Medicines List (most recent revision)
• The Trinidad and Tobago Essential Drugs List (most recent revision)
• The OECS Pharmaceutical Procurement Service Essential Medicines List (most recent revision)

The clinical safety findings that follow are drawn from this combined set. Where a specific finding is relevant only to a particular national list, it is noted in the relevant section.

Section 3: A Caribbean Clinical Interactions Atlas

Eight clinical themes drawn from real prescribing patterns

This section presents drug interactions organised by clinical theme rather than by drug name. Each theme reflects a prescribing pattern that Caribbean clinicians encounter routinely — in primary care clinics, in hospital wards, in pharmacies fielding questions across the counter. The interactions selected are not exhaustive. They are the ones most likely to cause patient harm and most often missed in everyday practice.

Each theme contains representative interactions drawn from the ElesRx database. Every interaction listed is validated against primary regulatory sources — DailyMed (US National Library of Medicine), LiverTox (US National Institutes of Health), Health Canada, and peer-reviewed literature indexed on PubMed and StatPearls. Severity classifications use the standard four-tier scale: Contraindicated, Major, Moderate, and Minor. Only Contraindicated and Major interactions are discussed here.

Where a Caribbean Practice Note appears, it highlights an aspect of the interaction with particular regional relevance — a commonly used herbal, a frequently prescribed antibiotic in island formularies, or a clinical scenario that recurs in Caribbean practice.

3.1 — Warfarin and the antibiotic problem

Warfarin remains the most widely used oral anticoagulant in Caribbean public-sector pharmacies. Direct oral anticoagulants are increasingly available in private practice, but warfarin still dominates in the public system because of cost and procurement reality. This means warfarin–antibiotic interactions are the single most frequent serious interaction problem Caribbean clinicians encounter.

The underlying mechanism is consistent. Antibiotics raise INR through one of three pathways: inhibition of the cytochrome P450 enzymes (mainly CYP2C9 and CYP3A4) that metabolise warfarin; suppression of gut bacteria that produce vitamin K; and in some cases displacement of warfarin from plasma albumin. The clinical result is the same — a previously stable INR rises within days, sometimes dramatically, with bleeding risk to match.

Six combinations carry the highest documented risk:

Clinical management: For any of these combinations, INR should be checked within 3–5 days of starting the antibiotic. A pre-emptive warfarin dose reduction of 25–50% is appropriate for fluconazole and clarithromycin. For shorter antibiotic courses (3–5 days), the INR rise may not stabilise during treatment but will be most pronounced 2–5 days after the course finishes, when warfarin metabolism normalises but accumulated drug effect remains.

Caribbean Practice Note: Sulfamethoxazole-trimethoprim is widely prescribed for urinary tract infections across Caribbean clinics. Nitrofurantoin is the preferred alternative in anticoagulated patients with uncomplicated cystitis and is generally well-tolerated. For respiratory infections, azithromycin produces less CYP3A4 inhibition than clarithromycin and is the safer macrolide choice in patients on warfarin.

3.2 — The herbal blind spot

Caribbean patients use bush teas, traditional preparations, and over-the-counter supplements in patterns that are often invisible to prescribing clinicians. Patients may not consider these "medications" worth mentioning, particularly when they are framed as food, drink, or natural remedies. Several of these compounds produce serious pharmacological interactions with conventional medicines.

The interactions below are not theoretical. Each has documented clinical cases, often including fatal outcomes.

Clinical management: Routine medication histories should explicitly ask about bush teas, herbal supplements, and "natural" remedies — open-ended questions about "anything else you take" are insufficient. Patients should be specifically counselled that herbal does not mean inert. For patients on warfarin specifically, the list of items that should be avoided or used only with INR monitoring is longer than commonly appreciated; cranberry juice and goji berry are frequently missed.

Caribbean Practice Note: Properly ripened ackee is safe and a culinary staple. The interaction described applies specifically to unripe ackee or improperly prepared ackee that retains hypoglycin A. Diabetic patients on insulin or sulfonylureas should be counselled about this distinction rather than advised to avoid ackee altogether — the latter advice is impractical and unlikely to be followed.

3.3 — QT prolongation in everyday prescribing

Drug-induced QT prolongation is rarely caused by a single agent at standard dose. The clinical problem almost always emerges from stacking — a patient on one moderately QT-prolonging drug is prescribed another, and a third agent that depletes potassium or magnesium completes the picture. The result is torsades de pointes, often in patients with no prior cardiac history.

The drug classes most often involved in Caribbean prescribing are not exotic. They are antibiotics, antifungals, antiemetics, antidepressants, and antipsychotics — all commonly co-prescribed.

Clinical management: Risk concentrates in patients with electrolyte disturbance (hypokalaemia, hypomagnesaemia), bradycardia, advanced age, female sex, structural heart disease, or congenital long QT syndrome. A baseline ECG is appropriate before initiating any combination of two or more QT-prolonging drugs. Serum potassium below 3.5 mmol/L and magnesium below 0.8 mmol/L should be corrected before initiating therapy and maintained throughout. A QTc above 500 ms or an increase of 60 ms or more from baseline warrants discontinuation of the offending agent.

Caribbean Practice Note: Chloroquine and hydroxychloroquine are still used regionally for malaria prophylaxis in travellers and for rheumatological indications. When patients on these agents present with infections requiring fluoroquinolone or macrolide therapy, the cumulative QT effect is frequently overlooked. Azithromycin is preferable to clarithromycin or erythromycin in patients already on hydroxychloroquine, and delafloxacin (where available) is the safest fluoroquinolone choice.

3.4 — MAOIs: old drugs, modern risks

Monoamine oxidase inhibitors are an older drug class, used today mainly for treatment-resistant depression and Parkinson's disease. Their prescribing volume is low, but they create disproportionate clinical risk because of two characteristics: the breadth of drugs they interact with, and the persistence of those interactions for 14 days after the MAOI is discontinued. Most fatal MAOI interactions occur not because the MAOI was started recently, but because another drug was prescribed without the prescriber realising an MAOI was on board.

Two additional factors elevate this theme's clinical importance. Linezolid — an antibiotic still used regionally for resistant Gram-positive infections — is a reversible MAOI, and is frequently prescribed without recognition of its MAOI activity. Methylene blue, used intraoperatively and for methaemoglobinaemia, also has MAOI activity. The interactions below therefore apply to a broader patient population than the term "MAOI" suggests.

Clinical management: Any patient on an MAOI requires an explicit washout period of 14 days before any of the contraindicated agents may be safely initiated. Fluoxetine requires a longer washout of at least 5 weeks before starting an MAOI, due to the long half-life of its active metabolite norfluoxetine. Selegiline at low Parkinson's doses (5–10 mg daily) is selectively MAO-B inhibitory and carries lower interaction risk, but higher doses lose selectivity and behave as non-selective MAOIs. Tyramine-restricted diet education is mandatory at MAOI initiation and reinforcement is appropriate at every clinic visit.

Caribbean Practice Note: Pseudoephedrine and phenylephrine are widely available in over-the-counter cold preparations across Caribbean pharmacies. Patients on MAOIs should be told explicitly to avoid all decongestants and to ask the dispensing pharmacist before purchasing any cold or flu remedy. Saline nasal sprays and steam inhalation are appropriate alternatives.

3.5 — The contraceptive failure interactions

Unintended pregnancy from drug interaction is one of the most preventable causes of contraceptive failure, and it is one of the most frequently missed in everyday prescribing. The mechanism is consistent: enzyme-inducing drugs accelerate hepatic metabolism of ethinyl estradiol and progestins, reducing plasma hormone levels below the threshold required for ovulation suppression. The clinical consequence is pregnancy in a patient who believed she was protected.

The interaction has particular relevance in Caribbean practice for two reasons. First, the public-sector oral contraceptive most commonly dispensed remains a combined ethinyl estradiol product — the formulation most affected by enzyme induction. Second, several of the inducing drugs are themselves teratogenic, meaning the pregnancy that results from contraceptive failure carries elevated fetal risk.

Clinical management: Patients prescribed any of the inducing drugs above should be specifically counselled that their oral contraceptive may fail, and that non-hormonal contraception (copper IUD, barrier methods) or a non-affected method (levonorgestrel IUD, depot medroxyprogesterone) is required during therapy. For rifampicin specifically, additional contraception is required during treatment and for at least 4 weeks after stopping. Simply increasing the oestrogen dose does not reliably overcome the induction effect and is not recommended.

A separate but related interaction concerns lamotrigine. Combined oral contraceptives induce UGT enzymes that metabolise lamotrigine, reducing plasma lamotrigine levels by approximately 50%. Patients on stable lamotrigine therapy who start an oral contraceptive may experience breakthrough seizures, and when the contraceptive is discontinued — including during pill-free intervals — lamotrigine levels rise sharply, risking toxicity. Continuous combined regimens are preferred to avoid this fluctuation.

3.6 — Methotrexate's quiet dangers

Methotrexate is one of the most widely prescribed disease-modifying agents in rheumatology and dermatology, used for rheumatoid arthritis, psoriasis, and several other conditions. It is also used at much higher doses in oncology. At low rheumatological doses (typically 7.5–25 mg weekly), methotrexate is generally well tolerated. The danger is interactional — methotrexate has a narrow therapeutic index, and several commonly prescribed drugs significantly elevate its plasma concentrations or toxicity.

Fatal cases of methotrexate toxicity have been documented even at low rheumatological doses when combined with the interacting drugs below. The combination with NSAIDs is particularly insidious because both classes are widely used in patients with inflammatory joint disease.

Clinical management: Patients on methotrexate should be counselled to avoid over-the-counter NSAIDs and to consult their prescriber before any new medication, including antibiotics for routine infections. Paracetamol is the preferred analgesic alternative. For patients with rheumatoid arthritis who genuinely require NSAID therapy, the lowest effective dose for the shortest duration is appropriate, with monitoring of full blood count and renal function. For surgical patients on methotrexate, the anaesthetic team should be informed in advance — nitrous oxide is best avoided.

Caribbean Practice Note: Sulfamethoxazole-trimethoprim is widely prescribed across Caribbean public-sector clinics for urinary tract infections and respiratory infections. In patients on methotrexate, this combination has caused fatal pancytopenia at standard antibiotic doses. Nitrofurantoin, doxycycline, or a cephalosporin are appropriate alternatives for most non-severe community infections.

3.7 — The transplant patient's pharmacy hazards

Caribbean solid-organ transplantation is increasing — both through regional transplant services and through patients who travel abroad for transplantation and return for ongoing care. These patients typically remain on lifelong immunosuppression with calcineurin inhibitors (ciclosporin or tacrolimus) or mTOR inhibitors (sirolimus), and they are at high risk of clinically significant drug interactions because these agents are CYP3A4 substrates with narrow therapeutic indices.

The clinical consequences of these interactions cluster around two opposite poles: drug levels too high, producing nephrotoxicity, neurotoxicity, and opportunistic infections; or drug levels too low, producing acute graft rejection. Either outcome can be irreversible.

Clinical management: Any new medication for a transplant patient — including over-the-counter products, antibiotics for community infections, and herbal supplements — should be cross-checked against the immunosuppressant before dispensing. Calcineurin inhibitor trough levels should be checked within 3–5 days of starting any potent CYP3A4 inhibitor or inducer, and dose adjustment is almost always required. Patients should be explicitly counselled to avoid grapefruit and grapefruit juice indefinitely, and to disclose all herbal supplements at every clinic visit.

For statin therapy in patients on ciclosporin, pravastatin and fluvastatin are the preferred options; simvastatin and lovastatin are contraindicated. For analgesia, paracetamol is preferred over NSAIDs. For antibiotic prescribing, azithromycin is preferred over clarithromycin, and fluconazole is preferred over itraconazole or voriconazole when antifungal therapy is required.

Caribbean Practice Note: Grapefruit is widely consumed in the Caribbean as fresh fruit and as juice. Patients returning home after transplantation abroad may not have received specific counselling on this — Caribbean clinicians should make grapefruit avoidance a standard part of every transplant patient's pharmaceutical care plan and should ask explicitly at follow-up. Seville oranges and pomelo carry the same risk.

3.8 — Live vaccines and immunosuppression

The expansion of biologic and targeted therapy across the Caribbean — for rheumatological disease, inflammatory bowel disease, oncology, and increasingly for dermatological conditions — has created a new and frequently overlooked interaction problem. Live attenuated vaccines, which require an intact immune response to replicate safely, can cause fatal disseminated infection when administered to patients on immunosuppressive therapy.

The list of immunosuppressants that contraindicate live vaccination is broader than commonly recognised. It includes not only traditional agents (azathioprine, methotrexate, ciclosporin, tacrolimus, mycophenolate) but also high-dose corticosteroids and the rapidly expanding biologic and small-molecule classes.

Common live vaccines that fall under this restriction include: MMR, varicella (chickenpox), zoster (Zostavax — but not the recombinant Shingrix, which is inactivated), yellow fever, oral typhoid (Ty21a — but the injectable Vi polysaccharide is inactivated), BCG, rotavirus, and live attenuated influenza (the intranasal spray — the injectable influenza vaccine is inactivated and safe).

Clinical management: All recommended live vaccinations should be completed at least 4 weeks before any planned immunosuppressive therapy. Inactivated vaccines (including injectable influenza, pneumococcal, hepatitis B, and inactivated COVID-19 vaccines) are safe during immunosuppression but may produce suboptimal immune responses — timing vaccination during the lowest immunosuppression intensity improves efficacy. Household contacts of immunosuppressed patients can receive most live vaccines, with the exception of oral polio vaccine.

Caribbean Practice Note: Yellow fever vaccination is a frequent issue for Caribbean patients on immunosuppressants who plan international travel, particularly to South America and Africa where yellow fever certification is required for entry. These patients cannot safely receive the vaccine. A medical exemption letter from the prescribing rheumatologist or oncologist is appropriate, and patients should be advised that some destinations may refuse entry despite documentation. Pre-travel risk assessment should occur well in advance of departure.

Section 3 in summary

Eight clinical themes have been presented. The themes are not exhaustive — the ElesRx database contains several hundred validated interactions of major or contraindicated severity beyond those discussed here. The themes selected reflect prescribing patterns that recur in Caribbean practice and where the consequences of missed interactions are most serious.

Three observations apply across the themes:

First, the highest-risk interactions are rarely between exotic drugs. They are between commonly prescribed agents — warfarin and antibiotics, NSAIDs and methotrexate, oral contraceptives and anticonvulsants, fluoroquinolones and antipsychotics. The clinical danger lies in the everyday combinations.

Second, the patient is often the source of the missing information. Herbal supplements, bush teas, over-the-counter products, and supplements purchased online are routinely undisclosed at consultation. Open-ended history questions are insufficient. Specific questioning about herbals, supplements, and traditional preparations is required.

Third, polypharmacy compounds risk geometrically. A patient on three QT-prolonging drugs is not at three times the risk of a patient on one — the risk is higher than additive, and depends on electrolyte status, age, and underlying cardiac substrate. The clinical implication is that medication review at every visit is appropriate practice, particularly in older patients and patients with multiple comorbidities.

The remaining sections of this report build on this clinical foundation. Section 4 examines the Beers Criteria and its application to Caribbean elderly care. Section 5 addresses the anticholinergic burden problem. Section 6 covers therapeutic duplications. Section 7 catalogues prescribing cascades. Together, the sections describe a regional pharmacotherapeutic landscape — and offer a framework for safer prescribing across it.

Section 4: The Beers Criteria Crossover

When essential medicines meet geriatric risk

The American Geriatrics Society (AGS) Beers Criteria is a regularly updated, evidence-based list of medications that are potentially inappropriate for adults aged 65 and older. First published in 1991 and most recently updated in 2023, it is the most widely referenced geriatric prescribing guideline in the world. Its purpose is not to prohibit — it is to prompt a second look.¹

This matters for Caribbean clinicians because older adults represent the fastest-growing segment of the region's patient population, and many of the medications flagged by the Beers Criteria are staples of Caribbean prescribing. Amitriptyline is still a first-line choice for neuropathic pain in some clinics. Promethazine is dispensed routinely for nausea. Diazepam remains on essential medicines lists across the region. These are not obscure drugs — they are everyday prescriptions.

ElesRx incorporates the Beers Criteria through its ElderWatch™ alert system, which flags potentially inappropriate medications in real time when a clinician enters a patient aged 65 or older. The data in this section is drawn directly from the ElderWatch database.

Disclaimer: ElesRx references the AGS Beers Criteria for educational and clinical decision-support purposes. ElesRx is not affiliated with, endorsed by, or sponsored by the American Geriatrics Society. The AGS Beers Criteria® is a registered trademark of the American Geriatrics Society.

4.1 How the Beers Criteria applies in the Caribbean

The Beers Criteria was developed in the United States, using evidence from predominantly North American and European populations. Caribbean clinicians sometimes question its relevance to their practice. Three points are worth noting.

First, the pharmacology does not change with geography. Amitriptyline has the same anticholinergic burden whether it is prescribed in Kingston or Kansas City. The physiological vulnerability of an older adult — reduced renal clearance, increased sensitivity to CNS-active drugs, diminished hepatic metabolism — is universal.

Second, the Caribbean context can make the risks worse, not better. Where routine laboratory monitoring is less available, where clinic visits are less frequent, and where patients may be managing multiple chronic conditions with limited specialist access, the margin for error narrows. A drug that requires careful monitoring in a well-resourced setting becomes a higher-risk prescription in a resource-constrained one.

Third, the Beers Criteria is not a prohibition list. It is a prompt for clinical judgement. Some flagged medications are the best available option in certain settings, and the Criteria acknowledges this. The goal is awareness, not avoidance at all costs.

4.2 ElderWatch-flagged drugs in the ElesRx database

The ElesRx database currently flags over 170 medications under the ElderWatch system, organised by therapeutic category. The table below summarises the categories and the most commonly encountered drugs within each.

Anticholinergics (33 drugs flagged)

This is the largest single category, reflecting the Beers Criteria's emphasis on anticholinergic burden as a major source of harm in older adults. The risks — confusion, dry mouth, constipation, urinary retention, delirium, falls, and an association with long-term cognitive decline — compound when multiple anticholinergic drugs are used together.

Caribbean Practice Note: Chlorpheniramine and promethazine are among the most frequently dispensed medications across the Caribbean, available over the counter in many territories. Diphenhydramine is widely used as a sleep aid. Clinicians should be aware that patients aged 65 and older may be self-medicating with these agents without reporting them.

Central Nervous System (58 drugs flagged)

The CNS category is the broadest, spanning benzodiazepines, antipsychotics, tricyclic antidepressants, barbiturates, and Z-drugs. The common thread is increased sensitivity in older adults, leading to falls, cognitive impairment, delirium, and — for antipsychotics in dementia — increased stroke risk and mortality.

Caribbean Practice Note: Diazepam remains on the Jamaica VEN list and the OECS EML. Amitriptyline is widely prescribed for neuropathic pain, depression, and migraine prophylaxis. Haloperidol is used routinely for acute psychosis and agitation in emergency settings. These drugs are not inappropriate in all circumstances, but their presence on essential medicines lists can create an assumption of safety that does not hold for older patients.

Cardiovascular (27 drugs flagged)

Cardiovascular agents represent a particularly important category because heart disease, hypertension, and atrial fibrillation are among the most common conditions managed in Caribbean primary care. Several first-line treatments carry Beers flags.

Caribbean Practice Note: Methyldopa is still prescribed for hypertension in some Caribbean settings, particularly in pregnancy carryover prescribing where it is continued post-partum without review. Nifedipine immediate-release capsules, which carry a risk of precipitous hypotension, remain available in some Caribbean pharmacies. Digoxin is used widely for atrial fibrillation and heart failure, but doses above 0.125 mg/day are associated with toxicity in older adults with declining renal function.

Endocrine (18 drugs flagged)

Caribbean Practice Note: Glyburide (known as glibenclamide in British pharmacopoeias and throughout the Caribbean) is one of the most commonly prescribed oral antidiabetics in the region due to its low cost and long-standing presence on essential medicines lists. It carries the highest risk of prolonged severe hypoglycaemia among oral antidiabetics in older adults. Where formularies allow, glimepiride or a non-sulfonylurea agent is preferred.

NSAIDs and Pain (20 drugs flagged)

Caribbean Practice Note: Diclofenac and ibuprofen are available over the counter across the Caribbean and are among the most commonly used analgesics. Patients aged 65 and older frequently self-medicate with these agents for chronic pain without clinician awareness. Indomethacin, which carries the highest CNS adverse effect risk among NSAIDs, is still used for acute gout in some settings where colchicine dosing is not well understood.

Gastrointestinal (10 drugs flagged)

Caribbean Practice Note: Omeprazole is heavily prescribed across the Caribbean, often continued indefinitely without a clear high-risk indication. The Beers Criteria recommends avoiding scheduled PPI use beyond 8 weeks unless the patient has erosive oesophagitis, Barrett's oesophagus, is on chronic NSAIDs, or is on corticosteroids. Periodic review of PPI necessity is a straightforward intervention that is frequently overlooked.

Muscle Relaxants (6 drugs flagged)

All skeletal muscle relaxants are flagged: Cyclobenzaprine, Carisoprodol, Methocarbamol, Orphenadrine, Metaxalone, and Chlorzoxazone. They are poorly tolerated in older adults due to anticholinergic effects, excessive sedation, and fall risk. Their effectiveness beyond short-term use is questionable. Where a muscle relaxant is deemed necessary, the lowest dose for the shortest duration should be used, with fall precautions in place.

4.3 Five Beers-flagged drugs to watch in Caribbean practice

The following five drugs were selected because they are widely prescribed in Caribbean clinical settings, frequently appear on regional essential medicines lists, and carry Beers flags that are commonly overlooked.

1. Amitriptyline

Why it is prescribed: Neuropathic pain, depression, migraine prophylaxis, insomnia.

Why it is flagged: Amitriptyline has one of the highest anticholinergic burdens of any commonly prescribed medication. In older adults, it increases the risk of confusion, dry mouth, constipation, urinary retention, orthostatic hypotension, falls, and cardiac conduction disturbances. The sedative effect that makes it attractive for insomnia is the same property that causes next-day drowsiness and impaired cognition in older patients.

Safer alternatives available in the Caribbean: For neuropathic pain, gabapentin or pregabalin (with renal dose adjustment). For depression, sertraline or escitalopram. For migraine prophylaxis, propranolol or valproate. For insomnia, non-pharmacological approaches are preferred; if medication is needed, low-dose trazodone or melatonin may be considered, though evidence is limited.

2. Diazepam

Why it is prescribed: Anxiety, seizure control, muscle spasm, alcohol withdrawal, procedural sedation.

Why it is flagged: Diazepam is a long-acting benzodiazepine with active metabolites that can accumulate over days in older adults. It increases the risk of cognitive impairment, delirium, falls, hip fractures, and motor vehicle accidents. Older adults have increased sensitivity to benzodiazepines — the same dose produces a greater and more prolonged effect than in younger patients.

Safer alternatives available in the Caribbean: For anxiety, SSRIs (sertraline, escitalopram) or buspirone. For seizure control, levetiracetam or valproate (with appropriate monitoring). For muscle spasm, non-pharmacological approaches or short-course low-dose alternatives. For alcohol withdrawal, lorazepam (shorter-acting, no active metabolites) is preferred if a benzodiazepine is required, with the shortest possible duration.

3. Glibenclamide (Glyburide)

Why it is prescribed: Type 2 diabetes mellitus — often as a first- or second-line oral agent due to cost and availability.

Why it is flagged: Glibenclamide has the longest duration of action among the sulfonylureas and carries the highest risk of prolonged, severe hypoglycaemia in older adults. Hypoglycaemia in this population can present atypically — as confusion, falls, or apparent stroke — and may be missed or misdiagnosed.

Safer alternatives available in the Caribbean: Metformin remains the preferred first-line agent (with renal function monitoring). If a sulfonylurea is needed, gliclazide modified-release or glimepiride have shorter durations and lower hypoglycaemia risk. Where available and affordable, DPP-4 inhibitors (sitagliptin, linagliptin) avoid hypoglycaemia entirely.

4. Promethazine

Why it is prescribed: Nausea, vomiting, allergic reactions, sedation, cough suppression.

Why it is flagged: Promethazine has a high anticholinergic burden combined with strong sedative properties. In older adults, it increases the risk of confusion, excessive sedation, extrapyramidal effects, and falls. Its use as an antiemetic is particularly problematic because alternatives with better safety profiles exist.

Safer alternatives available in the Caribbean: For nausea, ondansetron or domperidone. For allergic reactions, cetirizine or loratadine (second-generation antihistamines with minimal anticholinergic activity). For cough, non-pharmacological approaches or simple linctus.

5. Omeprazole

Why it is prescribed: Gastro-oesophageal reflux, peptic ulcer disease, gastroprotection with NSAIDs or corticosteroids, dyspepsia.

Why it is flagged: The concern is not short-term use — it is the indefinite continuation of PPIs beyond the initial indication. Long-term PPI use in older adults is associated with Clostridioides difficile infection, hypomagnesaemia (which can cause arrhythmias and seizures), and an increased risk of osteoporotic fractures. The Beers Criteria recommends avoiding scheduled PPI use beyond 8 weeks unless a specific high-risk indication is present.

What to do: Review PPI necessity at every medication review. If the original indication was short-term (a course of NSAIDs, an acute ulcer that has healed), step down to as-needed use or discontinue. If gastroprotection is still required (chronic NSAID or corticosteroid use, Barrett's oesophagus), continuation is appropriate but should be documented with a clear rationale.

4.4 The compounding problem: polypharmacy and the Beers list

The Beers Criteria flags individual drugs, but the real danger in Caribbean geriatric prescribing is accumulation. A patient aged 70 with hypertension, type 2 diabetes, osteoarthritis, insomnia, and mild depression might be prescribed amlodipine, glibenclamide, diclofenac, diazepam, and amitriptyline — all in a single consultation. Three of those five medications carry Beers flags. Two of them (diazepam and amitriptyline) compound each other's sedative and fall risk. The NSAID (diclofenac) combined with an antihypertensive reduces blood pressure control and increases renal risk.

This is not a hypothetical combination. It reflects real prescribing patterns seen in Caribbean primary care settings where formulary constraints, limited specialist access, and time-pressured consultations shape prescribing decisions.

The ElderWatch system in ElesRx was designed to flag these accumulations — not just individual drugs, but the cumulative risk profile of a patient's full medication list.

Section 5: High-Burden Anticholinergics in Regional Prescribing

The invisible accumulation

A patient takes promethazine for nausea. Amitriptyline for neuropathic pain. Oxybutynin for an overactive bladder. Each prescription is clinically defensible on its own. Together, they produce an anticholinergic burden score of 9 — a level strongly associated with cognitive decline, delirium, falls, and hospitalisation in older adults.

This is the anticholinergic burden problem. It is not about any single drug. It is about the sum.

5.1 The Anticholinergic Cognitive Burden (ACB) scale

The anticholinergic burden concept was formalised by Boustani and colleagues in 2008 and subsequently expanded by Kiesel and colleagues in 2018 through the German Anticholinergic Burden Scale (GABS). The combined ACB/GABS scale, accessible at acbcalc.com, assigns each drug a score based on the strength of its anticholinergic activity:

Score 1 — Possible anticholinergic activity. These drugs have measurable anticholinergic properties in laboratory assays but may not produce clinically obvious anticholinergic effects at standard doses. Individually, they are low risk. However, when several Score 1 drugs are prescribed together, the cumulative burden can reach clinically significant levels.

Score 2 — Definite anticholinergic activity. These drugs have established anticholinergic effects that are clinically relevant. They contribute meaningfully to total burden even in isolation.

Score 3 — Strong anticholinergic activity. These drugs have potent, clinically significant anticholinergic effects. A single Score 3 drug is sufficient to produce adverse effects in a vulnerable older adult, and two or more Score 3 drugs in combination represent a serious clinical concern.

The threshold for concern is a cumulative ACB score of 3 or higher. At this level, research consistently shows increased risk of confusion, falls, dry mouth, constipation, urinary retention, blurred vision, tachycardia, and — with sustained exposure — accelerated cognitive decline. A score of 6 or higher warrants urgent medication review.

Disclaimer: ElesRx anticholinergic burden scoring references the Anticholinergic Cognitive Burden (ACB) scale (Boustani et al., 2008) and the German Anticholinergic Burden Scale (GABS; Kiesel et al., 2018) as compiled at acbcalc.com. ElesRx is not affiliated with or endorsed by the developers of these scales.

5.2 ACB-scored drugs commonly prescribed in the Caribbean

The following table lists drugs present in the ElesRx database that carry ACB scores and are commonly encountered in Caribbean clinical practice. The list is not exhaustive — the full ACB/GABS scale includes over 400 medications — but focuses on drugs that Caribbean clinicians prescribe regularly or that patients may obtain over the counter.

Score 3 — Strong anticholinergic activity

These drugs contribute the most to anticholinergic burden. Each one alone reaches the threshold for clinical concern in an older adult.

Score 2 — Definite anticholinergic activity

Score 1 — Possible anticholinergic activity

These drugs individually carry minimal anticholinergic risk, but they accumulate. A patient on four or five Score 1 drugs can reach a clinically significant total burden without any single drug appearing high-risk.

Caribbean Practice Note: Several Score 1 drugs on this list — furosemide, atenolol, metoprolol, captopril, nifedipine, prednisolone, digoxin — are among the most commonly prescribed medications in Caribbean primary care. They rarely raise anticholinergic concerns individually, but in an older patient on five or six of them simultaneously, the cumulative score can reach 5 or 6 before a single "high-risk" anticholinergic is even added. This hidden accumulation is the reason cumulative scoring matters.

5.3 Three high-burden combinations to watch

The following three scenarios illustrate how anticholinergic burden accumulates in realistic Caribbean prescribing situations. All drug combinations reflect patterns commonly seen in primary care and pharmacy dispensing records.

Scenario 1: The neuropathic pain patient

Patient profile: 72-year-old woman with diabetic neuropathy, insomnia, and urinary incontinence.

The problem: Two Score 3 drugs alone produce a burden of 6. Add two Score 1 drugs and the total reaches 8 — a level associated with significant cognitive impairment and high fall risk. The patient may present with confusion or unsteadiness that is attributed to ageing or the diabetes itself, when the anticholinergic burden is the actual driver.

Lower-burden alternative:

The burden drops from 8 to 1 — a clinically transformative change — without sacrificing treatment of any condition. Gabapentin requires renal dose adjustment in older adults, and mirabegron may not be available or affordable in all Caribbean territories, but where these options exist, the benefit is substantial.

Scenario 2: The psychiatric patient in primary care

Patient profile: 68-year-old man with schizophrenia, insomnia, constipation, and seasonal allergies.

The problem: A cumulative score of 10 in a patient already vulnerable to cognitive effects from his psychiatric condition. The olanzapine is likely essential and difficult to substitute, but the chlorpheniramine and quetiapine are discretionary additions that contribute 5 points between them. The constipation the patient may be experiencing could itself be anticholinergic in origin — creating a potential prescribing cascade if a laxative is then added.

Lower-burden alternative:

The burden drops from 10 to 4 — still above the threshold, but the olanzapine is clinically necessary and the remaining Score 1 drug (furosemide) contributes minimally. The key intervention is removing the discretionary anticholinergics.

Scenario 3: The polypharmacy patient with no obvious culprit

Patient profile: 75-year-old man with hypertension, ischaemic heart disease, heart failure, COPD, gout, and mild anxiety.

The problem: Not a single drug on this list scores above 1. Every prescription is standard, defensible, and unremarkable in isolation. No individual drug would trigger an anticholinergic alert. Yet the cumulative score is 8 — firmly in the high-risk zone. This is the most insidious form of anticholinergic burden: the patient with no obviously anticholinergic drugs whose total burden is dangerous because of sheer medication count.

What to do: There may be no simple substitution here. The clinical intervention is awareness: recognising that the cumulative score is high, documenting it, monitoring for anticholinergic symptoms (confusion, dry mouth, constipation, urinary hesitancy, blurred vision), and avoiding the addition of any further anticholinergic agents. If any drug on the list can be deprescribed — for instance, if the alprazolam can be replaced with non-pharmacological anxiety management, or if the theophylline can be stepped down in favour of optimised inhaler therapy — the burden improves incrementally.

Caribbean Practice Note: This scenario reflects a prescribing pattern seen frequently in Caribbean general practice and pharmacy dispensing. None of the drugs would trigger a Beers alert on its own (digoxin is flagged only above 0.125 mg/day). The only way to identify the risk is to calculate the cumulative anticholinergic burden — which is precisely what the ElesRx ACB scoring module is designed to do.

5.4 Why cumulative scoring matters more than individual flags

The Beers Criteria (Section 4) flags individual drugs. The ACB scale measures the total burden across all drugs a patient is taking. These are complementary but different tools.

A clinician who checks only the Beers list will catch amitriptyline, diazepam, and oxybutynin. A clinician who also calculates the cumulative ACB score will catch the patient on eight Score 1 drugs whose total burden is equally dangerous but whose individual prescriptions are unremarkable.

In Caribbean clinical settings, where polypharmacy is common and formulary constraints often limit substitution options, cumulative burden scoring is arguably more useful than individual drug flags. It shifts the conversation from "is this drug safe?" to "is this patient's total medication burden safe?" — a question that encompasses the full complexity of real-world prescribing.

ElesRx calculates this automatically. When a clinician enters a patient's medication list, the system returns both individual ElderWatch flags and a cumulative ACB score, along with a risk-level classification:

Section 6: Therapeutic Duplications Common in Caribbean Prescribing

The prescription that cancels itself out — or doubles the harm

A therapeutic duplication occurs when a patient is prescribed two or more drugs from the same pharmacological class, acting through the same mechanism, for the same or overlapping indications. The result is rarely double the benefit. It is usually double the risk — of adverse effects, of toxicity, and of drug interactions that neither prescription alone would have triggered.

Therapeutic duplication is one of the most common and most preventable medication errors in clinical practice. It happens for predictable reasons: a patient sees multiple prescribers who do not share records; a brand name is not recognised as the same drug already on the list; a formulary substitution is made without discontinuing the original; or a hospital discharge medication is added on top of an existing outpatient regimen that was never reviewed.

In Caribbean clinical settings, where patients may attend both public and private clinics, where pharmacy dispensing records are not consistently shared between facilities, and where brand-name and generic availability varies between territories, the conditions for therapeutic duplication are present at every level of the system.

6.1 How ElesRx detects duplicates

ElesRx uses the four-level ATC-aligned drug class hierarchy in the pharmacoai database to identify therapeutic duplications. When two drugs in a patient's medication list share the same subclass — for example, two SSRIs, two beta-blockers, or two proton pump inhibitors — the system flags the pair for clinician review.

The system also accounts for route of administration. Two corticosteroids prescribed by different routes (for instance, oral prednisolone for an asthma exacerbation and a beclomethasone inhaler for maintenance) are not flagged, because the systemic exposure and clinical intent differ. Two oral beta-blockers, however, are flagged regardless of the indication recorded, because the pharmacological overlap and risk of additive adverse effects are present regardless of why each was prescribed.

Critically, ElesRx maintains a whitelist of clinically appropriate same-class combinations — pairs that appear to be duplicates but are in fact established, evidence-based regimens. These exceptions are suppressed from flagging. The whitelist is described in Section 6.3 below.

6.2 Eight duplicate patterns to recognise

The following patterns are drawn from the ElesRx database and represent the most commonly encountered therapeutic duplications in Caribbean clinical practice. Each pattern includes the class involved, why the duplication occurs, what the clinical risk is, and whether any whitelist exception applies.

Pattern 1: Two NSAIDs

Example: Ibuprofen + diclofenac, or naproxen + meloxicam.

Why it happens: A patient takes ibuprofen over the counter for headaches and is prescribed diclofenac by a clinician for musculoskeletal pain. Neither prescriber is aware of the other drug.

Clinical risk: Additive GI bleeding risk, increased risk of acute kidney injury, fluid retention, and cardiovascular events. Two NSAIDs provide no additional analgesic benefit beyond a single agent at adequate dose.

Exception: None. There is no clinical justification for concurrent use of two non-selective NSAIDs.

Pattern 2: Two benzodiazepines

Example: Diazepam + alprazolam, or clonazepam + lorazepam.

Why it happens: A patient is prescribed diazepam for anxiety by one clinician and alprazolam for insomnia by another. Alternatively, a long-acting benzodiazepine for maintenance is combined with a short-acting one for breakthrough symptoms without explicit documentation.

Clinical risk: Additive CNS depression, excessive sedation, respiratory depression, falls, cognitive impairment, and increased risk of dependence.

Exception: None in routine practice. In specialist settings (e.g., seizure management under neurologist supervision), overlapping benzodiazepines may be clinically justified, but this should be documented explicitly.

Pattern 3: Two SSRIs or an SSRI plus an SNRI

Example: Fluoxetine + sertraline, or fluoxetine + venlafaxine.

Why it happens: A switch from one antidepressant to another is initiated without adequate washout or discontinuation of the first. The patient ends up on both during a prolonged cross-taper, or the original prescription is simply never stopped.

Clinical risk: Serotonin syndrome — a potentially life-threatening condition characterised by agitation, tremor, hyperthermia, clonus, and in severe cases, seizures and cardiovascular collapse. Additive serotonergic effects also increase the risk of GI bleeding, hyponatraemia, and falls.

Exception: None. Two serotonergic antidepressants should not be prescribed concurrently outside of specialist psychiatric supervision during a carefully managed cross-taper.

Pattern 4: Two proton pump inhibitors

Example: Omeprazole + lansoprazole, or pantoprazole + esomeprazole.

Why it happens: Brand-name and generic PPIs coexist on Caribbean formularies, and patients may not recognise that two differently named drugs are pharmacologically identical. A hospital discharge adds pantoprazole to a patient already taking omeprazole at home.

Clinical risk: No additional acid suppression benefit. Increased exposure to PPI-associated adverse effects (C. difficile infection, hypomagnesaemia, fractures) without clinical gain.

Exception: None. A single PPI at appropriate dose is always sufficient.

Pattern 5: Two oral antidiabetics from the same class

Example: Glibenclamide + glipizide (two sulfonylureas), or metformin + metformin extended-release at overlapping doses.

Why it happens: A formulary change substitutes one sulfonylurea for another without explicitly discontinuing the original. A patient on glibenclamide from a public clinic obtains glipizide from a private pharmacy.

Clinical risk: For sulfonylureas, additive and potentially severe hypoglycaemia — particularly dangerous in older adults where hypoglycaemia may present as confusion, falls, or apparent stroke. For duplicate metformin formulations, increased GI adverse effects and potential for lactic acidosis in patients with unrecognised renal impairment.

Exception: None within the same subclass. However, metformin combined with an SGLT2 inhibitor (e.g., empagliflozin) is an established, evidence-based regimen and is whitelisted in the ElesRx duplicate exceptions table. Similarly, basal insulin combined with bolus (mealtime) insulin is an intentional therapeutic strategy and is whitelisted.

Pattern 6: Two opioids without documented rationale

Example: Tramadol + codeine, or morphine + oxycodone without clear documentation of breakthrough vs. baseline dosing.

Why it happens: A patient on regular tramadol for chronic pain is given codeine/paracetamol combination tablets for an acute exacerbation. Or a patient on slow-release morphine is switched to oxycodone without the morphine being stopped.

Clinical risk: Additive CNS and respiratory depression, excessive sedation, constipation, and increased overdose risk. Tramadol combined with another serotonergic opioid also carries serotonin syndrome risk.

Exception: Long-acting opioid + short-acting opioid for breakthrough pain is an established palliative care and chronic pain management strategy. This combination is whitelisted in the ElesRx duplicate exceptions table, but only when the two opioids serve clearly different roles (baseline vs. breakthrough). Two long-acting opioids, or two short-acting opioids, remain flagged.

Pattern 7: ACE inhibitor + ARB

Example: Lisinopril + losartan, or enalapril + valsartan.

Why it happens: Historically, dual renin-angiotensin blockade was trialled for nephroprotection in diabetic kidney disease and for heart failure. Some patients remain on both from legacy prescribing.

Clinical risk: The ONTARGET trial and subsequent evidence demonstrated that ACE inhibitor + ARB combination increases the risk of hypotension, hyperkalaemia, and acute kidney injury without meaningful benefit in most populations. Current guidelines recommend against dual blockade in the majority of patients.

Exception: This combination is flagged in ElesRx. Rare exceptions may exist under nephrologist supervision for specific proteinuric kidney disease, but these are specialist decisions that should be documented explicitly.

Pattern 8: Two first-generation antihistamines

Example: Chlorpheniramine + promethazine, or diphenhydramine + hydroxyzine.

Why it happens: A patient takes chlorpheniramine for allergies and is given promethazine for nausea or as a sedative. Both are available over the counter in many Caribbean territories.

Clinical risk: Extreme anticholinergic burden (both are ACB Score 3 drugs). Combined effects include severe sedation, confusion, delirium, urinary retention, constipation, tachycardia, and falls. In older adults, this combination is particularly dangerous.

Exception: None. A second-generation antihistamine (cetirizine, loratadine) should be used for the allergic component, and a non-anticholinergic antiemetic (ondansetron, domperidone) for nausea.

6.3 The whitelist: when duplication is intentional

Not every same-class combination is an error. Some are established, guideline-supported regimens where two drugs from related (but not identical) subclasses are prescribed together intentionally. ElesRx maintains a duplicate_exceptions table that suppresses flagging for these pairs.

The current whitelist includes:

These exceptions are defined at the subclass level in the database, meaning that all drug pairs within the excepted subclass combination are suppressed — not just specific brand-name pairs. The clinical rationale and source citation are stored alongside each exception for audit purposes.

Caribbean Practice Note: The statin + ezetimibe and dual antiplatelet combinations are well understood by most Caribbean clinicians. The loop + thiazide diuretic combination and the basal-bolus insulin regimen are less consistently recognised as intentional, and may trigger questions from pharmacists unfamiliar with the clinical rationale. The whitelist system allows ElesRx to suppress these flags while still catching genuine errors.

6.4 Why duplication detection matters more than it appears

Therapeutic duplication is often treated as a minor alert — less dramatic than a contraindicated interaction, less urgent than a drug allergy. This underestimates the problem.

A 2021 analysis by Riechelmann and colleagues found that therapeutic duplications accounted for a significant proportion of clinically relevant prescribing errors in hospital and ambulatory settings, particularly in patients with polypharmacy. In Caribbean primary care, where a single patient may collect prescriptions from a public hospital pharmacy, a private GP, and an over-the-counter purchase at a community pharmacy — all without a shared electronic record — the probability of duplication is higher than in any single-payer system.

The ElesRx duplicate detection module does not replace pharmacist review or clinician judgement. It provides an automated first-pass screen that catches the pairs most likely to be unintentional, while the whitelist ensures that intentional combinations are not buried under false alerts. The goal is signal, not noise.

Section 7: Ten Prescribing Cascades Involving Regional Medications

When treating the side effect becomes the disease

A prescribing cascade occurs when a drug's adverse effect is misinterpreted as a new medical condition, prompting a second prescription — which may itself cause further adverse effects, prompting a third. The term was formalised by Rochon and Gurwitz in 1997, and the pattern remains one of the most common and least recognised forms of iatrogenic harm in clinical practice.⁶

The mechanism is straightforward. A patient starts Drug A. Drug A causes a side effect. The side effect is attributed to a new or worsening condition rather than to Drug A. Drug B is prescribed to treat that perceived condition. In many cases, Drug B introduces its own adverse effects, and the cycle continues.

Prescribing cascades are particularly prevalent in older adults and in patients with polypharmacy — precisely the populations most vulnerable to adverse drug effects and least able to tolerate additional medications. In Caribbean clinical settings, where follow-up intervals may be long and medication lists may not be reviewed comprehensively at each visit, cascades can persist for months or years before being identified.

The ElesRx database contains 48 documented prescribing cascades across six clinical themes: core clinical cascades, psychiatric drug cascades, diabetes and endocrine cascades, cardiovascular cascades, renal and electrolyte cascades, and gastrointestinal cascades. This section presents ten selected cascades that are particularly relevant to Caribbean prescribing practice.

Cascade 1: NSAIDs → Hypertension → Antihypertensive → Oedema → Diuretic

Trigger drug: NSAIDs (ibuprofen, diclofenac, naproxen)

What happens: NSAIDs cause sodium and water retention, raising blood pressure. The elevated blood pressure is treated with an antihypertensive — commonly amlodipine, a calcium channel blocker. Amlodipine causes peripheral oedema (ankle swelling), which is then treated with furosemide, a loop diuretic. The patient has moved from one drug to three, and the original problem — pain — could have been managed with paracetamol.

Why it matters in the Caribbean: Diclofenac and ibuprofen are available over the counter across the region. Patients frequently self-medicate without informing their clinician. When blood pressure rises at the next visit, the NSAID is rarely considered as the cause.

How to break the cycle: Before adding an antihypertensive to a patient with newly elevated blood pressure, ask about NSAID use — including over-the-counter purchases. If chronic pain management is needed, consider paracetamol, topical NSAIDs, or non-pharmacological approaches. If an NSAID is genuinely required, use the lowest effective dose for the shortest duration and monitor blood pressure.

Cascade 2: ACE Inhibitor → Cough → Cough Suppressant

Trigger drug: ACE inhibitors (lisinopril, enalapril, ramipril)

What happens: ACE inhibitors cause a dry, persistent cough in up to 20% of patients — more commonly in women and in patients of African and Asian descent. The cough is mediated by bradykinin accumulation and is not responsive to standard cough treatments. When the cough is treated with codeine-containing cough suppressants rather than recognised as an ACE inhibitor side effect, the patient is exposed to unnecessary opioid risks (constipation, sedation, dependence) while the cough persists.

Why it matters in the Caribbean: ACE inhibitors are among the most widely prescribed antihypertensives in the region. The higher prevalence of ACE inhibitor cough in patients of African descent means this cascade is encountered more frequently in Caribbean practice than in many other settings.

How to break the cycle: Switch to an ARB (losartan, valsartan, telmisartan). ARBs provide equivalent cardioprotective and renal-protective benefit without the bradykinin-mediated cough. Do not add a cough suppressant without first reviewing the medication list for ACE inhibitors.

Cascade 3: Donepezil → Urinary Incontinence → Oxybutynin

Trigger drug: Donepezil (cholinesterase inhibitor for dementia)

What happens: Donepezil increases cholinergic activity, which can cause urinary urgency and incontinence. Oxybutynin — an anticholinergic — is prescribed for the incontinence. Oxybutynin directly opposes the mechanism of donepezil, reducing its efficacy for dementia while adding its own anticholinergic burden (confusion, dry mouth, constipation, further cognitive decline). The patient is simultaneously receiving a cholinergic drug and an anticholinergic drug, each undermining the other.

Why it matters in the Caribbean: This cascade is particularly harmful because the patient population — elderly adults with dementia — is the most vulnerable to anticholinergic adverse effects. As the Caribbean population ages and dementia prevalence rises, this cascade will become increasingly common. Mirabegron (a beta-3 agonist with no anticholinergic activity) is the preferred alternative for overactive bladder in patients on cholinesterase inhibitors, where available.

How to break the cycle: If a patient on donepezil develops urinary incontinence, consider donepezil as the cause before prescribing an anticholinergic. If bladder treatment is required, use mirabegron or non-pharmacological approaches (bladder training, pelvic floor exercises). Never add an anticholinergic to a patient on a cholinesterase inhibitor without documenting the clinical justification.

Cascade 4: Metoclopramide → Drug-Induced Parkinsonism → Levodopa

Trigger drug: Metoclopramide (dopamine antagonist, used for gastroparesis and nausea)

What happens: Metoclopramide crosses the blood-brain barrier and blocks dopamine receptors, causing drug-induced parkinsonism — tremor, rigidity, and bradykinesia that are clinically indistinguishable from idiopathic Parkinson's disease. The parkinsonism is misdiagnosed as a new neurological condition and treated with levodopa or other antiparkinsonian agents, exposing the patient to unnecessary medication with its own side effects (nausea, dyskinesia, hallucinations).

Why it matters in the Caribbean: Metoclopramide is widely available and frequently prescribed for nausea, gastroparesis, and as a prokinetic agent. Drug-induced parkinsonism is one of the most commonly missed diagnoses in elderly patients. The Beers Criteria flags metoclopramide specifically for its risk of tardive dyskinesia in older adults.

How to break the cycle: Discontinue metoclopramide. Drug-induced parkinsonism typically resolves within weeks of stopping the offending agent. Use domperidone (where available and not contraindicated) as a safer prokinetic alternative, as it does not cross the blood-brain barrier to the same extent. If a patient on metoclopramide develops parkinsonian features, stop the metoclopramide before starting antiparkinsonian therapy.

Cascade 5: Thiazide Diuretic → Hyperuricaemia → Allopurinol

Trigger drug: Thiazide diuretics (hydrochlorothiazide, chlorthalidone, indapamide)

What happens: Thiazide diuretics reduce renal uric acid excretion, raising serum urate levels. In susceptible patients, this precipitates acute gout. Allopurinol is then prescribed for the gout — a lifelong medication to treat a condition caused by another lifelong medication. In some cases, allopurinol itself causes a hypersensitivity reaction (particularly in patients of African or South-East Asian descent carrying the HLA-B*5801 allele), adding a third layer of iatrogenic harm.

Why it matters in the Caribbean: Thiazide diuretics are first-line antihypertensives across the region due to their low cost and established efficacy. Gout prevalence in the Caribbean is significant, and the connection between thiazide use and gout flares is not always recognised promptly.

How to break the cycle: If a patient develops new-onset gout after starting a thiazide, consider the diuretic as the cause. Where blood pressure control allows, switching to a loop diuretic (which has less effect on uric acid) or an alternative antihypertensive class may resolve the hyperuricaemia without requiring long-term allopurinol.

Cascade 6: Amlodipine → Ankle Oedema → Diuretic

Trigger drug: Amlodipine (dihydropyridine calcium channel blocker)

What happens: Amlodipine causes dose-dependent peripheral oedema — ankle swelling — in a significant proportion of patients. The oedema is caused by arteriolar vasodilatation (not fluid overload), but it is frequently misinterpreted as heart failure or fluid retention and treated with a diuretic. The diuretic is ineffective for vasodilatory oedema and introduces its own risks: electrolyte disturbances, dehydration, orthostatic hypotension, and — in the case of thiazides — hyperuricaemia and gout (triggering Cascade 5).

Why it matters in the Caribbean: Amlodipine is one of the most commonly prescribed antihypertensives in the region. The ankle oedema it causes is dose-related and particularly noticeable in warm climates, which may increase the frequency of misattribution in Caribbean practice.

How to break the cycle: Recognise amlodipine-induced oedema as a pharmacological effect, not a disease. Reducing the dose often resolves it. If the full dose is needed for blood pressure control, adding an ACE inhibitor or ARB can reduce the oedema through venodilation (this is a pharmacological intervention, not a cascade). Do not add a diuretic for amlodipine-induced oedema.

Cascade 7: Opioid → Constipation → Laxative

Trigger drug: Opioid analgesics (codeine, tramadol, morphine, oxycodone)

What happens: Virtually all opioids cause constipation by binding to mu-opioid receptors in the gastrointestinal tract, reducing peristalsis. Unlike most opioid side effects, tolerance to constipation does not develop. A laxative is prescribed — usually a stimulant or osmotic agent — which may cause abdominal cramping, diarrhoea, or electrolyte disturbances. In some cases, the constipation is severe enough to require additional interventions, and the patient ends up on multiple bowel-management agents alongside the opioid.

Why it matters in the Caribbean: Codeine-containing analgesics and tramadol are widely prescribed and dispensed across the region. Constipation is accepted as an inevitable opioid side effect rather than a preventable one. Prophylactic laxative prescribing at the time of opioid initiation — standard in palliative care — is inconsistently practised in primary care.

How to break the cycle: Prescribe a prophylactic laxative at the time of opioid initiation, not after constipation develops. Review the ongoing need for the opioid at every visit. For chronic non-cancer pain, non-opioid alternatives should be considered. If opioid therapy is continued long-term, the laxative is not a cascade — it is appropriate co-prescribing, but only when initiated proactively.

Cascade 8: Antipsychotic → Drug-Induced Parkinsonism → Antiparkinsonian Agent

Trigger drug: Antipsychotic agents (haloperidol, chlorpromazine, risperidone, olanzapine)

What happens: Antipsychotics, particularly first-generation agents, block dopamine D2 receptors and can cause extrapyramidal symptoms — tremor, rigidity, akathisia, and bradykinesia. These symptoms are treated with anticholinergic antiparkinsonian agents (benztropine, trihexyphenidyl), which add anticholinergic burden and carry their own risks: confusion, dry mouth, urinary retention, constipation, and — in older adults — delirium and cognitive decline.

Why it matters in the Caribbean: First-generation antipsychotics (haloperidol, chlorpromazine) remain widely used in Caribbean psychiatric practice due to cost and availability. The routine co-prescribing of benztropine or trihexyphenidyl as "prophylaxis" against extrapyramidal symptoms is common but adds significant anticholinergic burden, particularly in older patients. Second-generation antipsychotics with lower extrapyramidal risk (where available and affordable) may reduce the need for anticholinergic co-prescribing.

How to break the cycle: Use the lowest effective antipsychotic dose. Consider whether a second-generation agent with lower extrapyramidal risk is available and appropriate. If extrapyramidal symptoms develop, dose reduction or switching should be considered before adding an anticholinergic agent. If an anticholinergic must be used, plan for regular review and attempt withdrawal after 3–6 months.

Cascade 9: SSRI → Insomnia → Sedative/Hypnotic

Trigger drug: SSRIs (fluoxetine, sertraline, escitalopram, paroxetine)

What happens: SSRIs can cause initial insomnia, restlessness, or sleep disruption — particularly in the first weeks of treatment. Rather than adjusting the timing of the SSRI dose (moving it to the morning), reducing the dose, or waiting for the effect to settle, a sedative-hypnotic is prescribed: typically a benzodiazepine (diazepam, alprazolam) or a Z-drug (zolpidem). The sedative introduces dependence risk, cognitive impairment, falls, and — in older adults — delirium, while the underlying SSRI side effect may have resolved spontaneously.

Why it matters in the Caribbean: Benzodiazepines remain the most commonly prescribed sedatives in the region, often continued indefinitely. Adding a benzodiazepine to an SSRI at initiation — sometimes as a deliberate "bridging" strategy — frequently results in the benzodiazepine being continued long after the SSRI has taken full effect.

How to break the cycle: Counsel patients that initial insomnia with SSRIs is common and usually transient (1–2 weeks). Adjust the SSRI dose timing to the morning. If sleep remains problematic, review sleep hygiene before prescribing a sedative. If a short-course benzodiazepine is used as a bridge, set a firm stop date at initiation and document it.

Cascade 10: Metformin → GI Upset → Proton Pump Inhibitor

Trigger drug: Metformin (biguanide, first-line oral antidiabetic)

What happens: Metformin commonly causes gastrointestinal adverse effects — nausea, abdominal discomfort, bloating, and diarrhoea — particularly at initiation or dose escalation. These symptoms are attributed to dyspepsia or gastro-oesophageal reflux, and a proton pump inhibitor is prescribed. The PPI does not address metformin-induced GI symptoms (which are not acid-related) and introduces its own long-term risks: C. difficile infection, hypomagnesaemia, and fractures. Meanwhile, simple strategies — slow dose titration, taking metformin with food, or switching to an extended-release formulation — would have addressed the original problem.

Why it matters in the Caribbean: Metformin is the most widely prescribed oral antidiabetic in the region. PPIs are already overused (as discussed in Section 4). The combination of these two prescribing habits — starting metformin at full dose and reaching for a PPI at the first sign of GI discomfort — creates a cascade that is both common and entirely preventable.

How to break the cycle: Start metformin at a low dose (250–500 mg daily) and titrate slowly over 2–4 weeks. Take with meals. If GI intolerance persists, switch to metformin extended-release before adding any additional medication. Do not prescribe a PPI for metformin-induced GI symptoms without evidence of acid-related disease.

The common thread

All ten cascades share two features. First, the side effect of Drug A was not recognised as a side effect. Second, the default response was to add a new drug rather than to question the existing one. This is not a failure of clinical knowledge — most clinicians, when asked directly, would identify the side effect correctly. It is a failure of clinical workflow: the side effect is encountered in the context of a busy clinic, with multiple problems to address, and the fastest path is a new prescription rather than a medication review.

The ElesRx cascade detection module is designed to interrupt this pattern. When a clinician enters a medication list that contains both a known trigger drug and a known secondary drug, the system alerts to the potential cascade — giving the clinician the context to ask whether the second drug is treating a genuine condition or masking a side effect of the first.

Section 8: Clinical Takeaways

Seven things this report asks you to remember

This report has covered drug interactions, Beers Criteria flags, anticholinergic burden, therapeutic duplications, and prescribing cascades — a substantial volume of clinical safety data. Not all of it will be relevant to every clinician on every day. But the following seven points apply broadly across Caribbean clinical practice, and each one represents a concrete action that can be taken at the next patient encounter.

1. Caribbean prescribing draws on a distinct formulary, and safety references should match.

The drugs prescribed most commonly in the Caribbean — chlorpheniramine, promethazine, diclofenac, glibenclamide, amitriptyline, diazepam, metoclopramide — are not always the same drugs that dominate prescribing in North America or Europe. Clinical decision support tools built for other markets may not prioritise the interactions, flags, and cascades most relevant to regional practice. Caribbean clinicians benefit from safety references that reflect the drugs they actually prescribe.

2. The herbal blind spot is real.

Patients across the Caribbean use herbal preparations — ackee, cerasee, soursop leaf, fever grass, guinea hen weed, and others — alongside their prescribed medications, often without disclosing this to their clinician. Some of these herbals carry clinically significant interactions: ackee with antidiabetics (hypoglycin A toxicity), St. John's Wort with contraceptives and antiretrovirals (CYP3A4 induction), and warfarin with a wide range of herbal products. Asking about herbal use should be routine at every medication review.

3. Anticholinergic burden accumulates silently — score every elderly patient.

No single Score 1 anticholinergic drug looks dangerous. Five of them together produce a cumulative burden associated with cognitive decline, delirium, falls, and hospitalisation. The patient on furosemide, atenolol, digoxin, warfarin, and theophylline has a cumulative ACB score of 5 without a single obviously anticholinergic drug on the list. Cumulative scoring catches what individual drug flags miss.

4. Five Caribbean staples carry significant Beers warnings — and safer alternatives exist regionally.

Amitriptyline, diazepam, glibenclamide, promethazine, and omeprazole (beyond 8 weeks) are among the most commonly prescribed medications in the Caribbean, and all carry Beers Criteria flags for adults aged 65 and older. For each, a safer alternative is available in most Caribbean formularies: gabapentin for neuropathic pain, sertraline for depression, gliclazide for diabetes, cetirizine for allergies, and PPI deprescribing where the original indication has resolved.

5. Therapeutic duplication is more common than it appears — especially across prescribers.

When a patient attends both a public clinic and a private pharmacy, or when a hospital discharge adds to an existing outpatient regimen without reconciliation, duplicate prescriptions from the same drug class are easily missed. Two NSAIDs, two benzodiazepines, two PPIs, or two sulfonylureas double the risk without doubling the benefit. A medication list review that checks for same-class overlap takes less than a minute and can prevent significant harm.

6. Prescribing cascades are missed when each new symptom is treated as a new disease.

The pattern is consistent: Drug A causes a side effect. The side effect is interpreted as a new condition. Drug B is prescribed. Drug B causes its own side effect. Drug C is prescribed. The patient's medication list grows, their risk increases, and the original culprit is never identified. Before adding a new medication, ask: could this symptom be caused by something the patient is already taking?

7. The "triple whammy" is the single most preventable acute kidney injury pattern.

The combination of an ACE inhibitor or ARB, an NSAID, and a diuretic — sometimes called the "triple whammy" — is a well-documented cause of acute kidney injury, particularly in older adults and in patients with pre-existing renal impairment. All three drug classes are commonly prescribed in Caribbean primary care, and the combination frequently occurs when an NSAID is added (often over the counter) to a patient already on an ACE inhibitor and a diuretic for hypertension or heart failure. This combination should be actively screened for at every medication review.

These seven points are not exhaustive. They are a starting point — a checklist that can be applied immediately, without additional training, without additional resources, and without waiting for a system-level change. Each one is a question a clinician can ask at the next patient encounter.

Section 9: About ElesRx

Every analysis in this report — drug interactions, Beers Criteria screening, anticholinergic burden scoring, prescribing cascade detection, and therapeutic duplicate identification — is performed automatically by ElesRx.

ElesRx is a clinical decision support tool built for Caribbean clinicians. A clinician enters a patient's medication list, and ElesRx returns a comprehensive safety analysis: drug-drug and drug-class interactions with severity grading and management guidance, ElderWatch™ alerts for patients aged 65 and older (based on the AGS Beers Criteria), cumulative anticholinergic burden scoring (based on the ACB/GABS scale), prescribing cascade detection across 48 documented cascade patterns, and therapeutic duplicate identification with a clinically curated whitelist of appropriate same-class combinations.

The tool also provides pregnancy and lactation safety summaries, renal and hepatic dosing flags, and drug monograph links from publicly accessible, commercially licensed sources.

ElesRx is available at elesrx.com. The free tier supports up to three saved patient profiles. The full-access tier, at $9.99 per month, removes profile limits and provides access to all clinical modules.

ElesRx is a product of PIPPS Smart Apps, a division of J.C. Epiphany Limited (Jamaica, est. 1998).

Section 10: Methodology and References

10.1 Data sources

All drug interaction data, Beers Criteria flags, anticholinergic burden scores, prescribing cascades, and therapeutic duplicate rules presented in this report are drawn from the ElesRx clinical database (pharmacoai), which is maintained and curated by the author.

The database was constructed using the following source hierarchy, selected for clinical authority and commercial licensing compatibility:

Sources explicitly excluded from the ElesRx database for licensing reasons: DrugBank (commercial licence required for commercial use) and the WHO Essential Medicines List (CC BY-NC-SA — non-commercial use only).

10.2 Beers Criteria reference

ElderWatch™ alerts are based on the American Geriatrics Society 2023 Updated AGS Beers Criteria® for Potentially Inappropriate Medication Use in Older Adults.¹ ElesRx references the Beers Criteria for clinical decision-support purposes and is not affiliated with, endorsed by, or sponsored by the American Geriatrics Society. Beers Criteria® is a registered trademark of the American Geriatrics Society.

10.3 Anticholinergic burden scoring reference

Anticholinergic burden scores are based on the Anticholinergic Cognitive Burden (ACB) scale developed by Boustani and colleagues (2008)² and expanded by the German Anticholinergic Burden Scale (GABS) developed by Kiesel and colleagues (2018),³ as compiled at acbcalc.com. ElesRx is not affiliated with or endorsed by the developers of these scales.

10.4 Interaction validation

All interactions in the ElesRx database are marked with a validated flag. An interaction is validated when its mechanism, severity, and management guidance have been confirmed against at least one primary source (DailyMed labelling or peer-reviewed literature). Interactions referenced in Section 3 of this report are drawn exclusively from the validated subset of the database.

The database uses a class-first interaction architecture: interactions are defined at the drug-class level where pharmacologically appropriate, with drug-specific overrides where individual agents within a class behave differently. This approach reduces redundancy while preserving clinical accuracy.

10.5 Prescribing cascade documentation

The 48 prescribing cascades in the ElesRx database were compiled from peer-reviewed literature, clinical guidelines, and the foundational work of Rochon and Gurwitz (1997).⁶ Each cascade documents the trigger drug or class, the expected side effect, the secondary drug typically prescribed, and — where the cascade extends further — the tertiary drug. Clinical tips and population-specific notes are included for each cascade.

10.6 Limitations

This report is a clinical reference document, not a systematic review. It does not claim to be comprehensive or to represent every drug interaction, Beers flag, or prescribing cascade relevant to Caribbean practice. The data reflects the current state of the ElesRx database at the time of publication and will be updated as the database grows.

The Caribbean Essential Medicines Lists referenced in Section 2 (Jamaica VEN, Trinidad and Tobago EDL, OECS EML) are subject to periodic revision. Specific medicine counts and revision dates should be confirmed against current official publications.

Drug availability, pricing, and regulatory status vary across Caribbean territories. Recommendations regarding safer alternatives are general and should be confirmed against local formulary access before implementation.

This report is not a substitute for clinical judgement. All prescribing decisions should be made in the context of the individual patient, their medical history, and the available evidence.

10.7 Author and conflict of interest disclosure

This report was authored by Juliet Duncan, BPharm, founder of J.C. Epiphany Limited and developer of ElesRx. The author has a commercial interest in ElesRx. This report is published freely and without an access gate as a contribution to Caribbean clinical education. No external funding was received for its preparation.

10.8 Citation

Duncan J. The Caribbean Clinical Interactions Atlas: Drug Interactions and Safety Risks Across Regional Prescribing. ElesRx Clinical Reports, Report 1. Published 2026 at elesrx.com/reports/caribbean-clinical-interactions-atlas/. J.C. Epiphany Limited, Jamaica.

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7. O'Mahony D, Cherubini A, Guiteras AR, et al. STOPP/START criteria for potentially inappropriate prescribing in older people: version 3. Eur Geriatr Med. 2023;14(4):625–632. doi:10.1007/s41999-023-00777-y

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