Pharmaceutical Equivalence of Some Commercial Samples of Artesunate and Amodiaquine Tablets Sold in Southwestern Nigeria

Purpose: To study the physical properties and dissolution profiles of commercial samples of artesunate and amodiaquine tablets.
Methods: Fifteen generic brands of artesunate and five generic brands of amodiaquine tablets were obtained from drug retail outlets in Oyo and Ogun States in southwestern Nigeria. The tablets were subjected to various compendial tests including identification, weight uniformity, uniformity of content, content of active ingredient and uniformity of diameter. Additional tests used as a basis for the assessment of the pharmaceutical equivalence of the products include hardness, disintegration time and dissolution rate. Data obtained were analysed by correlation analysis, Chi-square and ANOVA.
Results: Thirteen generic brands of artesunate (87 %) and four amodiaquine brands (80 %) investigated were imported. Two brands of the imported artesunate brands were found to contain undetectable amount of artesunate while another 8 samples contained overages. All the amodiaquine brands passed the assay test as stipulated by United States Pharmacopoeia (USP) for amodiaquine tablets while tablet disintegration time of amodiaquine products ranged from 5.8 - 20.7 min. All but one artesunate sample passed the disintegration test too. A majority of the artesunate brands tested had significantly different dissolution profiles (p < 0.05). Four (80 %) of the amodiaquine tablet brands tested had similar dissolution profiles and percent drug released within 30 min (p > 0.05). One amodiaquine brand demonstrated poor dissolution profile as it did not meet minimum dissolution requirements within 30 min.
Conclusion: The detection of substandard artesunate tablets and a poorly formulated amodiaquine tablet amongst the few sample brands studied highlights the need for increased drug surveillance and monitoring of the qualities of antimalarial medicines currently in use in order to prevent widespread treatment failure.

Keywords
Artesunate tablets; Amodiaquine tablets; Tablet hardness; Disintegration time; Dissolution profile; Pharmaceutical equivalence; Drug surveillance and monitoring.