Non-prescription medicine use by outpatients of a hospital in north-central Trinidad living with hypertension, and the potential clinical risks

Objective To describe the reported use of non‐prescription medicines (NPMs) and the reported frequency of use by outpatients living with hypertension; to identify potential drug‐drug and drug‐disease interactions between reported NPMs and either antihypertensives prescribed or hypertension.

Setting Adult outpatient clinics of the Eric Williams Medical Sciences Complex Adult Hospital in Trinidad.

Method Outpatients were interviewed about their use of NPMs using a structured instrument. Chi‐squared test or Fisher's exact test was used to test for associations between NPM use and selected variables: age group, gender, education level, number of prescribed medicines, use of prescribed medicines and the presence of comorbidities. Combinations of NPMs and antihypertensive drugs or hypertension itself that may lead to undesirable interactions were identified.

Key findings One hundred and fifty‐five clients were interviewed (mean age 61 years; 46% men; 56% of East Indian descent). Of these, 82% were living with a cardiac condition and 60% with diabetes mellitus. In addition, 92% reported using NPMs to treat minor illnesses. Analgesic use was reported by 81%. Some 66% reported using paracetamol, 54% reported antitussives, 48% antacids, 47% antihistamines and 39% said they used sympathomimetic drugs. The majority (98%) of NPMs were used only when needed. Sixty per cent had at least one combination a with risk of interaction with NPMs and hypertension or antihypertensive medicines: 16% had risk of interactions between enalapril (or captopril) and antacids, 13% between angiotensin‐converting enzyme (ACE) inhibitors and non‐steroidal anti‐inflammatory drugs (NSAIDs), 12% between beta‐blockers and NSAIDs and 12% between thiazide diuretics and NSAIDs. Thirty‐nine per cent had a drug‐disease interaction risk due to sympathomimetic drugs and 26% had one due to NSAID use.

Conclusion Based on self‐reports, outpatients living with hypertension in north‐central Trinidad use NPMs when needed to treat minor illnesses, mainly paracetamol for pain. Non‐prescription‐antihypertensive interactions may arise due to ACE inhibitor/antacid combinations and NPM‐hypertension interactions may result from use of sympathomimetics. Interactions may also arise as a result of the use of NPMs containing NSAIDs and sodium.