Folic acid: a biopharmaceutical evaluation

Abstract

The aqueous solubility and drug product dissolution are important factors that determine the rate and extent of drug absorption from immediate release solid oral dosage forms. The aim of this article was to perform a folic acid biopharmaceutical study to evaluate the biowaiver of new products containing folic acid. We studied the solubility of its raw material and the dissolution profile of two commercially available products. Three different buffers (pH 1.2, 4.5 and 6.8) were used as the media of the solubility and dissolution tests (apparatus II, at 50 rpm and 900 mL of medium volume). We found that folic acid solubility and its release from tablets are pH dependent. The dissolution profiles of both tablets were compared by dissolution efficiency (%), using t-test or variance analysis (ANOVA). The dissolution profiles obtained for the two products at pH 1.2 medium were similar (p > 0.05), but they were dissimilar at pH 4.5 and 6.8 (p < 0.05). Furthermore, we could observe differences between all the dissolution profiles of folic acid for each product at three different dissolution media used. The results showed that physicochemical characteristics of folic acid affect its dissolution and absorption making it difficult to take a decision on their biowaiver based on BCS.