Formulation and evaluation of microemulsion system for transdermal delivery of nimodipine
The purpose of this study was to construct novel o/w microemulsion formulation for transdermal delivery of Nimodipine. Capmul PG 8 as the oil, Tween 20 as the surfactant, polyethylene glycol 400 as the cosurfactant screened as phases of microemulsions, due to a good solubilizing capacity of the microemulsion systems and excellent skin permeation rate of Nimodipine. The pseudo-ternary phase diagrams for microemulsion regions were constructed using Capmul PG 8 as the oil, Tween 20 as the surfactant, polyethylene glycol 400 as the cosurfactant. Various microemulsion formulations were prepared from Surfactant and cosurfactant ratio 2:1 and the abilities of various microemulsions to deliver Nimodipine through the skin were evaluated in vitro using Keshary-Chein diffusion cells ﬁtted with rat skins. The in vitro permeation data showed that microemulsions increased the permeation rate of Nimodipine over the control solution of Nimodipine. The optimum formulation consisted of 1.5 % Nimodipine, 5% Capmul PG 8, 25 % Tween 20/PEG (2:1) and 68.5 % water, showed a high permeation rate of 0.407 mg/cm2/h. These results indicate that the optimized formulation of Nimodipine microemulsion may be used as a promising vehicle for transdermal delivery of Nimodipine.
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