Influence of the timing of ultrasound application on the penetration of corticosteroids.

ABSTRACT

BACKGROUND: The application of ultrasound to enhance the transdermal transport of drugs is often referred to as 'sonophoresis'. In physiotherapy sonophoresis is applied to the skin through two different procedures (1) the pre-treatment procedure where the skin is treated with ultrasound irradiation prior to the drug application and (2) a simultaneous treatment mode, where the skin is treated with ultrasound during the application of the pharmacologic substance. The aim of this study was to compare the bioavailability of halcinonide in the stratum corneum comparing the ultrasound pre-treatment vs. the simultaneous treatment method. METHODS: The effect of pre and simultaneous ultrasound treatment (1 MHz, 1 W/cm(2)) was evaluated on the halcinonide blanching response using tristimulus colorimetry 2 h after the initial application. RESULTS: Within the evaluation period, only the ultrasound pre-treatment method resulted in a significant blanching response. CONCLUSION: Timing of the ultrasound application seems to influence the availability and percutaneous penetration process and should be taken into account when estimating the ultrasound enhancing effect.