Potential drug-drug interactions among elderly patients on anti-hypertensive medications in two tertiary healthcare facilities in Ekiti State, South-West Nigeria

Abstract

Introduction: Drug-drug interactions remain a major cause of adverse drug reactions with great consequences such as increased morbidity and increased healthcare cost. In elderly patients with systemic hypertension, there is a tendency for them to be prescribed multiple medications and this may expose them to some drug-drug interactions (DDIs) especially in the context of physiological changes of ageing. The objective of this study was to evaluate potential drug-drug interaction among some Nigerian elderly hypertension. Methods: A cross-sectional study involving elderly hypertensive patients attending the general outpatient clinic of two tertiary healthcare facilities located in Ekiti State, South-West Nigeria. The information collected from the patients′ medical records included their ages, gender, diagnosis and list of prescribed anti-hypertensive medications. Potential drug-drug interactions were checked for using the Multi-Drug Interaction Checker (Medscape Reference) and Epocrates Drug Interaction Checker (San Mateo CA, USA). Results: A total of 350 elderly patients attended the clinics during the study period of which 208 (59.4%) hypertensive patients were identified and their records used for analysis. The fixed-dose combination drug Moduretic® (Amiloride /Hydrochlorothiazide)-25.7% was the most commonly prescribed antihypertensive followed by Lisinopril (16.6%), Amlodipine (13.2%) and Nifedipine (12.6%). The anti-platelet Acetyl-salicylic acid (ASA) was prescribed for 100 (48.1%) patients and represented 19.8% of all prescribed medications. A total of 231 potential DDIs were found among the patients giving a mean of 1.3 interactions per patient. The most common identified drug pairs with potential interactions were ACE inhibitors - Amiloride, followed by ACE inhibitors - Hydrochlorothiazide, ACE inhibitors - ASA and ARB - Amiloride. Conclusion: Potential drug-drug interactions, though common in this study comprised mainly of minor and moderate types. Notwithstanding, physicians need to be reminded of the potential for interactions when prescribing for elderly patients

Keywords

• Anti-hypertensive medications
• drug-drug interactions
• drug utilization
• geriatric patients
• polypharmacy