Detection of anthralin in skin during treatment.

Free anthralin was detected in the stratum corneum and in hair follicles in histological sections of patients with psoriasis undergoing short contact therapy. A solution of sodium borate was used to provoke a yellow fluorescent complex. There was a strong fluorescence especially on the plaques and anthralin could be detected in psoriatic plaques up to 48 hours after treatment. It was difficult to completely eliminate the drug by washing with soap and anthralin could even be detected on non-treated areas.