Low frequency sonophoresis: A noninvasive method of drug delivery and diagnostics

Transdermal drug delivery offers an attractive alternative to injections an d oral medications. However, applications of transdermal drug delivery are limited to only a few drugs as a result of low skin permeability. Applicati on of low-frequency ultrasound enhances skin permeability, a phenomenon ref erred to as low-frequency sonophoresis. In this method, a short application of ultrasound is used to permeabilize skin for a prolonged period of time. During this period, ultrasonically permeabilized skin may be utilized for drug delivery. In addition, a sample of interstitial fluid or its component s may be extracted through permeabilized skin for diagnostic applications. In this paper, we report our in vivo studies that demonstrate the principle s of both of these concepts. Detailed studies on drug delivery are performe d using inulin and mannitol as model drugs. Studies on diagnostics are perf ormed using glucose as a model analyte. Applications of this technology to drug delivery and diagnostics are discussed.