Effect of PH on the release profile of glibenclamide tablets

Abstract

Nigeria as a developing country, is experiencing challenges of upsurge in uncommon diseases coupled with poor quality drugs to treat them. The type 2 diabetes is one such diseases and due to higher cost of newer medications, glibenclamide tablets remain the drug of choice for most sufferers. However, the low bioavailability as a result of intrinsic poor dissolution and pH-dependent solubility has cast doubts on the rationale behind its continued use as drug of choice. The effect of pH on the release rate of six brands sourced from pharmacy premises, hospital pharmacies and patent medicine stores in Jos metropolis was analyzed using dissolution studies at pH 1.2 and 6.8. Dissolution efficiency (DE) and similarity factors were used to determine generic brand suitability and substitutability with the innovator drug, Daonil®. The results showed that at pH 1.2, the solubility medium showed poor elease compared with pH 6.8. The results of DE study showed significance in generic differences with Daonil® and between brands. The similarity factors indicate that two brands (E_P5 and F_P6) were not bioequivalent with the innovator drug as evidenced by their F₁, F₂ and DE results. Therefore, all six brands of glibenclamide tablets cannot substitute or be interchanged for one another. In conclusion, pH plays critical role in the release of glibenclamide tablets implying that the drug should best be taken in fed state than fasted state. The place of purchase of the tablets had no bearing on their quality and some brands are not bioequivalent with the innovator brand.

Keywords: Glibenclamide tablets, solubility, dissolution, pH, similarity factor, dissolution efficiency