RESUMEN
BACKGROUND AND PURPOSE: The purpose of this investigation was to determine whether application of hydrocortisone phonophoresis enhances transcutaneous delivery of topically applied hydrocortisone in humans, as determined by blood cortisol levels. SUBJECTS: The subjects were 16 men and women, between the ages of 18 and 33 years (X = 25, SD = 2.74), without symptoms of any ongoing inflammatory condition. METHODS: A gel coupling medium containing 10% hydrocortisone acetate was used. Ultrasound was delivered over a 50-cm2 area for 5 minutes at an intensity of 1.0 W/cm2 and a frequency of 1.0 MHz. Each subject received a control treatment (ultrasound alone) and an experimental treatment (hydrocortisone phonophoresis) on the volar aspect of the forearm 1 week apart. Blood was drawn, under both control and experimental conditions, from a cubital vein just proximal to the treatment site prior to each treatment and 0,5, and 15 minutes posttreatment. Serum cortisol concentrations were measured using a fluorescence polarization immunoassay. RESULTS: No rise in serum cortisol concentrations following hydrocortisone phonophoresis was detected. CONCLUSION AND DISCUSSION: These findings suggest that there was no penetration of hydrocortisone through the epidermis and into the underlying vasculature. Clinical implications regarding hydrocortisone levels within the subcutaneous tissues are discussed, and further research is suggested.