Assessing the Burden of Substandard and Falsified Medicines in Community Pharmacies Across Katsina State, North West Nigeria: A Systematic Sampling Study

Substandard and falsified medicines represent a critical threat to pharmaceutical safety, therapeutic efficacy, and antimicrobial resistance control in Nigerian communities. Evidence on the scale of this problem at the community pharmacy level in North West Nigeria remains limited. This study assessed the burden of substandard and falsified medicines available at community pharmacies across Katsina State using a systematic sampling approach. A multi-stage sampling strategy was employed, with 80 community pharmacies selected across urban and rural zones of Katsina State. Samples of five high-risk tracer medicines including amoxicillin capsules, artemether-lumefantrine tablets, ciprofloxacin tablets, paracetamol tablets, and metronidazole tablets were collected and subjected to quality testing using pharmacopoeial standard methods including disintegration, dissolution, weight variation, and high-performance liquid chromatography analysis for active ingredient quantification. Of 400 samples tested, 23 percent failed at least one pharmacopoeial quality test. Falsification was confirmed in 8 percent of tested samples based on active ingredient content below 80 percent of labeled quantity. Antimalarials had the highest failure rates at 31 percent. Rural pharmacies had significantly higher failure rates than urban pharmacies. Medicines without NAFDAC registration numbers constituted 16 percent of samples. These findings document a substantial substandard and falsified medicine burden in Katsina State and demand urgent regulatory intensification, consumer education campaigns, and supply chain verification systems at community pharmacy entry points. Keywords: substandard medicines, falsified medicines, community pharmacy, Katsina State, medicine quality