Effect of Permeation Enhancer on the Diffusion of Carvedilol from the Buccal Adhesive Tablets

Carvedilol is a non selective α and β receptor blocker which undergoes extensive hepatic first pass metabolism by liver and has poor oral bioavailability of 25% - 30%. In the present investigation Carvedilol was formulated as a bilayered buccal adhesive tablets in order to avoid the first-pass effect and decrease the drug loss using two different natural polymers and excipients. Six formulations were made using different concentrations (17%w/w, 35%w/w, 53%w/w) of Pectin and Guar gum. Formulation F5 was selected for further studies of permeability. Three concentrations of SLS (1%, 1.5% & 2%w/w) was used to study the effect of permeation enhancer and improve the permeability of drug. The formulations were tested for % weight variation, hardness, Friability, % Drug content, in-vitro drug release, surface pH, Swelling index and Mucoadhesive strength. Mucoadhesive strength was determined by the modified balance method in grams and was found to be between 23.75±0.332gm to 60.89±0.134gm and Surface pH was found to be 7. In-vitro release studies revealed that as polymer concentration increases from 17% to 53%w/w, rate of drug release was retarded and the data was fitted into pharmacokinetic models. Among all other formulations, formulations (F5) containing 35%w/w Guar gum were found to be best as the release was retarded upto 8 hours and they have good mucoadhesive strength and they follow zero order with non-fickian diffusion mechanism. Formulation F9 (2%w/w SLS) shows more permeability of drug (34%) compared to other formulations.