The purpose of this research was to develop a matrix-type transdermal therapeutic system containing Clonidine hydrochloride with different ratios of hydrophilic and hydrophobic polymeric combinations by the solvent evaporation technique. The physicochemical compatibility of the drug and the polymers was studied by Infrared spectroscopy and U.V. spectrophotometry. The results suggested no physicochemical incompatibility between the drug and the polymers. In vitro permeation studies were performed by using Keshary -Chien cell. The results followed Higuchi kinetics (r = 0.9953-0.9979), and the mechanism of release was diffusion mediated. Based on physicochemical and in vitro skin permeation studies, patches coded as B9 (Eudragit L-100-55: PVP K-30, 3:1) and D2 (Eudragit L-100-55: HPC, 3:1) were chosen for further studies. The bioavailability studies in rats indicated that the Clonidine hydrochloride transdermal patches provided steady-state plasma concentrations with minimal fluctuations and improved bioavailability of 82.12% (for B9) and 75.90% (for D2) in comparison with oral administration. These patches go for further Skin and Stability studies. Skin irritation studies indicated that formulation produced no or very mild skin irritation. Stability studies indicated that on the basis of first order degradation kinetics and t 0.5 Shelf life was calculated to be 2.98 and 2.79 yrs.The developed transdermal patches increase the efficacy of the therapy of hypertension.
