s The Evaluation of Valsartan Biopharmaceutics Properties

Background: Solubility, intestinal permeability and dissolution are the main factors that govern the rate and extent of drugs absorption and are directly related to bioavailability. Biopharmaceutics Classification System (BCS) is an important tool which uses in vitro results for comparison with bioavailability in vivo (biowaiver). Valsartan is widely used in the treatment of hypertension and shows different BCS classification in the literature (BCS class II or III). Objective: This work proposes the study of valsartan biopharmaceutics properties and its BCS classification. Methods: High Performance Liquid Chromatography (HPLC) method was developed and validated to quantify the drug in buffers pH 1.2, 4.5 and 6.8 respectively. Valsartan solubility was determined in these three different media using shake flask method and intrinsic dissolution rate. Evaluation of dissolution profile from coated tablets was conducted. Results: The low solubility (pH 1.2 and 4.5) and high solubility (pH 6.8) were observed for both solubility methods. Permeability data reported from the literature showed that valsartan is a low permeability drug. Valsartan presented the rapid release profile only in pH 6.8. Conclusion: We defined that valsartan is a class IV drug, in disagreement with what has been published so far. It is important to emphasize that the conditions considered here are indicated to define the biopharmaceutics classification by regulatory agencies.