Phonophoretic delivery of dexamethasone to human transdermal tissues : A controlled pilot study

Corticosteroid phonophoresis is a widely utilized treatment for a variety of musculoskeletal inflammatory conditions. Its acceptance has been based on numerous efficacy studies performed in both animal models and the clinical setting, however, many of these studies have been problematic. The transdermal delivery of corticosteroids by phonophoresis has yet to be demonstrated directly in humans. The purpose of this study was to examine the efficacy of utilizing ultrasound to deliver a corticosteroidal medication, dexamethasone (DXM), transdermally in humans. 10 male subjects (age range = 19 to 34 years) were randomly assigned to either group A which received phonophoresis with DXM or to group B which received sham phonophoresis with DXM (topical application of DXM with no ultrasound). Blood samples were collected prior to or during the following time intervals (1, 3.5, 5, 15, 30, 60, and 120 min) after phonophoresis with DXM or sham phonophoresis with DXM. Using reverse-phase, high performance liquid chromatography (HPLC), DXM was detected at 30- and 60-min post-administration of DXM via phonophoresis in one individual and at 60- and 120-min post-administration of DXM by phonophoresis in a second individual. No DXM was detected in the blood plasma of individuals that received sham phonophoresis with DXM. Results from this study indicate that ultrasound was efficacious in delivering DXM or one of its metabolites transdermally to venous blood of human males. This study also suggests that phonophoretically applied DXM may experience a delay prior to entry of transdermal tissues.