Trend and Future Prospectus of Ultrasound Mediated Transdermal Drug Delivery- SONOPHORESIS

Application of ultrasound enhances skin permeabilit y to drugs, a phenomenon referred to as sonophoresi s. Significant strides have been made in sonophoresis research in recent years, especially under low-freq uency conditions (20 kHzbfb100 kHz). This article reviews the mechanistic principles and current status of s onophoresis under low-frequency conditions. Several therapeutic macromolecules including insulin, low molecular weight heparin, and vaccines have been delivered using low -frequency sonophoresis in vivo. Clinical trials ha ve been performed with several drugs including lidocaine an d cyclosporin. Novel theoretical and experimental a pproaches have provided insights into the mechanisms of low-f requency sonophoresis. Low-frequency ultrasound (US) applied on the skin (sonophoresis) may enhance the transdermal transport of various steroids. Experimental studies have shown that ultrasound waves (US) high low frequencies bring about a sort of disaggregation of the horny layer and stimulate convective movements within the epidermis, facilitating the absorption of the active com pounds (transdermal delivery). Ultrasound, on enhancing pr otein penetration into the sclera, a non-invasive m ethod to overcome the first barrier in taking the transscler al route for delivering therapeutics. Current under standing of these mechanisms is presented.