ABSTRACT
In this study, various matrix type transdermal patches containing carvedilol of variable combination of polyvinylpyrrolidone (PVP) and ethylcellulose (EC) were prepared by solvent evaporation technique. The patches were prepared by adding surfactant (sodium lauryl sulphate) to promote drug penetration which was found to increase transdermal transport. Therapeutic frequency ultrasound (1 MHz) and surfactant have been individually shown to enhance transdermal drug transport. In this study, we investigated the synergistic effect of ultrasound and surfactants on transdermal drug delivery. This study provides an investigation of the dependence of therapeutic-frequency sonophoresis on various ultrasound parameters, including ultrasound pretreatment time and the distance of the horn from the skin. Based on the in vitro release and in vitro permeation profile the formulation Fs1 (PVP/EC 1:2) shows the best release. Ultrasound was applied to pretreat the skin using a sonicator operating at a frequency of 1 MHz at an intensity 2 Watts/cm2. The optimum ultrasonication time of 50 min at a distance of 1 cm shows the best release. The skin conductivity enhancement was found to be inversely proportional to the distance of horn from the skin and it is directly proportional to ultrasonication pretreatment time. These findings will be useful in optimizing therapeutic-frequency sonophoresis.