Development and in-vitro evaluation of transdermal matrix films of metoprolol tartrate.

The transdermal matrix films of metoprolol tartrate (MT) were prepared by casting on mercury substrate employing different ratios of polymers, ethyl cellulose (EC) and polyvinyl pyrrolidone (PVP), using dibutyl phthalate (DBT) as a plasticizer. Four formulations were prepared. Formulations MF-1, MF-2, MF-3 and MF-4 were composed of EC and PVP in the following ratios: 4.5:0.5, 4:1, 3:2 and 2:3 respectively. The formulations were subjected to various physical characterization studies namely, thickness, weight variation, drug content, moisture uptake, in vitro drug release and in vitro skin permeation. The in vitro permeation studies were carried out across excised porcine ear skin using Franz diffusion cell. Cumulative amounts of the drug released in 24 hours from the four formulations were 69.58%, 96.13%, 98.85% and 99.60%, respectively. Corresponding values for the cumulated amounts of drug permeated across the porcine skin for the above matrix films were 124.38, 153.22, 156.46 and 163.25 mug/cm(2) respectively. By fitting the data into zero order, first order and Higuchi model, it was concluded that drug release from matrix films followed Higuchi model (r(2)=0.9147-0.9823), and the mechanism of release was diffusion mediated. Based on the physical evaluation, in vitro drug release & permeation characteristics, it was concluded that for potential therapeutic use, monolithic drug matrix films MF-3, composed of EC: PVP (3:2), may be suitable for the development of a transdermal drug delivery system of MT.