Equivalence in Active Pharmaceutical Ingredient of Generic Antihypertensive Medicines Available in Nigeria (EQUIMEDS): A Case for Further Surveillance

Abstract

Background: Widespread access to good quality antihypertensive medicines is a critical component for reducing premature cardiovascular disease (CVD) mortality. Poor-quality medicines pose serious health concerns; however, there remains a knowledge gap about the quality of cardiovascular medicines available in low- and middle-income countries.

Objectives: The aim of this study was to determine the quality of generic antihypertensive medicines available in the retail market of a developing country.

Methods: Samples of the 2 most commonly prescribed classes of antihypertensive medicines were collected from 3 states in 3 different geopolitical zones in Nigeria following a semirandom sampling framework. Medicine samples were purchased by mystery shoppers from 22 pharmacy outlets from 6 local government areas across the 3 states. Medicine quality was determined by measuring the amount of stated active pharmaceutical ingredient using high-performance liquid chromatography with photodiode array detection and classified according to their compliance to the specified pharmacopeia tolerance limits for each antihypertensive drug.

Results: Amlodipine and lisinopril were identified as the most commonly prescribed antihypertensive drugs in Nigeria. In total, 361 samples from 22 pharmacies were collected and tested. In total, 24.6% of amlodipine and 31.9% of lisinopril samples were of substandard quality and significantly more samples purchased in rural (59 of 161, 36.7%) compared with urban (32 of 200, 16%) outlets were found to be of substandard quality (p < 0.001). No falsified samples of either amlodipine or lisinopril were detected. There was large variation in price paid for the antihypertensive medicines (range ₦150 to ₦9,750). Of the 24 pharmacy outlets surveyed, 46% stated that patients did not always require a prescription and 21% had previously reported a medicine as falsified or substandard.

Conclusions: More than one-quarter of some commonly prescribed antihypertensive medicines available in Nigeria may be of substandard quality. Enhanced quality assurance processes in low- and middle-income countries, such as Nigeria, are needed to support optimum management.