Cumulative percent drug release of fi lms in pH 6.6 phosphate buffer
It was also concluded that formulation F5 (containing SCMC and HEC) and F6 (containing SCMC and PVP K-90) showed good swelling, a convenient residence time as well as promising drug release. On the basis of release pattern, swelling and residence time, F5 and F6 formulations were chosen for ex vivo study. In ex vivo study, drug permeation through the porcine buccal mucosa was determined for formulation F5 and F6 (Fig. 2). The drug permeation was found to be 82.48 % and 90.86 % in F5 and F6 after 10 h. The drug permeation decreased in ex vivo study in comparison of in vitro release. This decrease in drug diffusion observed from ex vivo study compared to in vitro, may be due to the lesser permeability of porcine mucosa and also the presence of a backing membrane in the ex vivo study, which make the release unidirectional. The backing membrane restricting the contact of the film with the receptor fluid to one side alone slows down the water uptake, swelling and disruption of the matrix in turn releasing lesser amount of drug in specified time, compared to the one without the backing membrane. The correlation coefficient values were found to be 0.9852 and 0.9667 for F5 and F6, respectively showing good correlation. It may be concluded that the release kinetics followed zero order. The Higuchi Plots of F5 and F6 were found to be almost linear with correlation coefficient values of 0.9310 and 0.9748. This proves that the drug permeation followed the matrix diffusion process.
Fig. 2
Fig. 2
Ex vivo permeation studies of selected mucoadhesive buccal films of enalapril
The results of all the physical characterization of all formulations (F1-F10) were found to be satisfactory. The results of the study show that therapeutic levels of enalapril can be delivered buccally. The present study concludes that these erodible mucoadhesive buccal films containing enalapril can be very promising for effective doses to systemic circulation. These may also provide an added advantage of circumventing the hepatic first pass metabolism. Films exhibited controlled release over more than 2 h. It was concluded that the films containing 20 mg of enalapril maleate in Sodium carboxymethylcellulose 2% w/v and hydroxyethyl cellulose 2% w/v (formulation F5), showed good swelling, a convenient residence time and promising controlled drug release, thus can be selected for the development of buccal film for effective therapeutic uses. Further, the study may be extended for assessing the in vivo release and in vitro-in vivo correlation.