Pharmacokinetics of doxepin in subjects with pruritic atopic dermatitis.

Author(s): Drake LA, Cohen L, Gillies R, Flood JG, Riordan AT, Phillips SB, Stiller MJ

Affiliation(s): Dermatology Clinical Investigations Unit, Pediatric Psychopharmacology Unit, Boston, MA 02114-2696, USA.

Publication date & source: 1999-08, J Am Acad Dermatol., 41(2 Pt 1):209-14.

Publication type: Clinical Trial; Randomized Controlled Trial

BACKGROUND: Doxepin applied topically by itself or in combination with triamcinolone acetonide is a safe and effective treatment for atopic dermatitis. OBJECTIVE: We evaluated the pharmacokinetic profile of doxepin and desmethyldoxepin after topical application of doxepin hydrochloride 5% cream alone or in combination with 0.025% triamcinolone acetonide (doxepin/TAC). METHODS: Twenty-four subjects with atopic dermatitis received either doxepin or doxepin/TAC cream 4 times daily for 7 days in a randomized, double-blind, controlled trial. Serum samples were obtained and pharmacokinetic parameters estimated from the dose-normalized serum concentrations of doxepin and desmethyldoxepin. Efficacy and adverse experiences were determined by physician and subject evaluations. RESULTS: Pharmacokinetic parameters (K(e ), t(1/2 ) and AUC) calculated in 9 subjects (doxepin/TAC = 4 subjects, doxepin = 5 subjects) with detectable serum concentrations were similar for both groups. Pruritus relief and lessening of pruritus severity were significantly greater with doxepin/TAC than doxepin alone. CONCLUSION: Topically applied doxepin is safe and effective therapy for pruritus.