Enhancement of bioavailability of carbamazepine through formulation of a solid dispersion based suspension

The objective of the work was to enhance the bioavailability of carbamazepine (CBZ), a poorly soluble drug, through formulation of a suspension using its solid dispersions. The solid dispersions were formulated with hydrophilic carriers like Polyethylene glycol 6000 (PEG 600), Polyvinylpyrrolidone (PVP), Hydroxypropyl methylcellulose (HPMC) by solvent evaporation method. They were characterized by infrared (IR) spectroscopy and Differential scanning calorimetric (DSC) studies. Based on the in vitro dissolution studies, the best solid dispersion was formulated into a suspension. It was further evaluated for drug content, particle size, drug release, sedimentation, and in vivo bioavailability. A marked increase in dissolution and bioavailability was exhibited by CBZ suspension made from its solid dispersion with HPMC, in the ratio of 1: 0.5. AUC was increased about 4.3 folds; C_max increased about 3.2 folds and t max reduced by 2.3 times, when compared to the conventional suspension. The solid dispersion system of carbamazepine with a hydrophilic polymer HPMC has provided a simple method of preparing a suspension of carbamazepine with increased bioavailability.