Topical Estradiol Can Be Transferred by Skin Contact

FRIDAY, Oct. 27 (HealthDay News) -- One hour after topical estradiol has been applied, a clinically significant transfer of the drug can occur during 15 minutes of skin contact, according to a report in the October issue of the Journal of Investigative Dermatology.

Ronald C. Wester, Ph.D., of the University of California San Francisco, and colleagues conducted an experiment to determine absolute bioavailability from skin rubbing or contact by applying a topical dose of 0.1 mg of radiolabeled estradiol to three groups of six volunteers each.

In group A, the dose site was protected with a non-occlusive cover, while in group B the dose site was unprotected. The skin area on group C volunteers was dosed and then rubbed by volunteers in group D, who had not received any dose.

Among the recipients in group A, 73-74 percent of the drug was still detectable on the skin, while in group B, 27-29 percent was detected on the skin and 14-24 percent was detected on their clothing. In group C, the residual dose was 36 percent on the skin and 13 percent on the sleeve, while for group D the residual doses (from the group C subjects) were 2.3 percent and 4.1 percent for skin and sleeve, respectively.

"The potential for skin transfer of topical bioactive chemicals has been shown in vivo in human volunteers and an awareness of this effect should be heeded," the authors conclude.

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