Formulation Development and Evaluation of Buccoadhesive tablets of Labetalol Hydrochloride.

Buccoadhesive tablets of Labetalol Hydrochloride were developed to prolong its release and improve the bioavailabilty by avoidance of hepatic first pass metabolism during the treatment of hypertension.The present study was designed to formulate and develop 8 prototype controlled release Bioadhesive Tablets formulations (Viz: F1 to F8) using Labetalol HCl as a model drug. It has a low bioavailability (OBA-25%), shorter biological half life (t1/2-4-6hr). Based on the preformulation studies 8 optimised formulations were prepared by direct compression using a swelling agent viz: Carbopol 934P and controlled release polymers such as HPMC K4M and Sodium alginate in different concentration. Backing layer of Eudragit RS in IPA was used .The resultant mucoadhesive tablets were evaluated for different quality parameters including in-vitro dissolution study, in-vitro diffusion study and invitro bioadhesion strength. The data obtained from dissolution studies was fitted in 5 models viz: Zero order, First order, Higuchi Matrix, Korsmeyer Peppas and Erosion plot. Mathematical analysis of the release kinetics indicated that the nature of drug release from the matrix tablets was dependent on drug diffusion and polymer relaxation and therefore followed non-Fickian or anomalous release approaching Zero order kinetics. The bioadhesive strength was found to be a function of nature and concentration of polymer used. The optimized batch containing 12%HPMC K4M and 12% Sodium Alginate showed cumulative drug release of 93.91% for 8 hrs and showed surface p H value of 6.43. Stability studies performed for a month at (40 degrees/75%RH) exhibited absolutely non significant variations.