Distribution and deposition of tritiated cortisol using phonophoresis.

Tritiated cortisol cream was coupled with light-microscopic autoradiography to histologically trace the distribution and deposition of a topical application of cortisol driven in by a therapeutic dose of ultrasound. Fifteen dogs were divided into four distinct groups: Group 1 consisted of two control dogs; Group 2, four dogs that received 10% radioactive cortisol and no ultrasound; Group 3, four dogs that received 5% radioactive cortisol plus ultrasound; and Group 4, five dogs that received 10% radioactive cortisol plus ultrasound. Although the cortisol applied to all dogs was limited to the epidermis, penetration occurred beyond the stratum corneum. The combination of 10% cortisol and ultrasound showed more penetration than 10% cortisol alone (p = .018), suggesting that ultrasound may be useful in the transdermal delivery of cortisol cream. The difference between the penetration of 5% and 10% cortisol when treated with ultrasound was only marginally significant (p = .062).