TRANSDERMAL DELIVERY OF METOPROLOL .1. COMPARISON BETWEEN HAIRLESS MOUSE AND HUMAN CADAVER SKIN AND EFFECT OF N-DECYLMETHYL SULFOXIDE

Metoprolol (MP) is a potent beta1-selective adrenergic blocking agent with proven antihypertensive activity. However, it undergoes extensive hepatic first-pass metabolism and has a short biological half-life which necessitate frequent dosing to attain adequate therapeutic blood levels. To overcome this problem, the feasibility of systemic delivery of MP via the transdermal route was explored. A monolithic polyacrylate adhesive dispersion type delivery system containing MP free base was fabricated and in vitro skin permeation studies were conducted at 37-degrees-C across excised full thickness hairless mouse and dermatomed human cadaver skins. Skin permeation rate across human cadaver skin was found to be lower than that of hairless mouse. Skin permeation profiles across both types of skins showed a membrane permeation controlled Q vs t linear relationship. Skin permeation rate was found to be dependent both on adhesive film thickness and loading dose of the drug in the matrix. Maximum skin permeation rate was obtained from a system having 1.5 mm thickness with a 10% (w/w) loading dose. n-Decylmethyl sulfoxide was found to enhance skin permeation rate of MP through human cadaver skin at a loading dose of 5% (w/w).