QUALITY ASSESSMENT OF SOME BRANDS OF CLARITHROMYCIN AND AZITHROMYCIN TABLETS USING THE CONCEPT OF DISSOLUTION EFFICIENCY AND SIMILARITY FACTOR

Counterfeit and substandard pharmaceutical products circulate widely in developing countries, yet adequate techniques to monitor quality is lacking. We report herein a quick and reliable approach to predict the in-vitro bioequivalence and interchangeability of common antibiotics using nine model drugs; four brands of azithromycin and five brands of clarithromycin tablets marketed in Nigeria. Pharmacopoeia guidelines (British and United States) were used to assess tablet quality such as friability, disintegration and dissolution times. All the brands tested passed the British Pharmacopoeia standard for disintegration time and their hardness and friability values were also considered adequate. There were no significant differences in the dissolution profiles of the brands, however, the azithromycin brands released >70% of the active drug within 30 min. The calculated similarity factor values for the azithromycin and clarithromycin brands were between 61 to 100 and 46 to 100 respectively. Based on the in-vitro tests, all the brands of azithromycin were considered bioequivalent with the innovator brand. However, only one brand had a similarity factor very close to that of the innovator brand and could be considered interchangeable. All the brands of clarithromycin were also considered bioequivalent, except one brand. Our results show that, the concept of dissolution efficiency could be a reliable method of predicting bioequivalence of antibiotics thereby serving as a tool to monitor and prevent the circulation of fake and counterfeited drug products.