Atopic dermatitis (eczema)

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Does tachyphylaxis occur in long-term management of scalp seborrheic dermatitis with pyrithione zinc-based treatments?

Int J Dermatol. 2009 Jan;48(1):79-85

Authors: Schwartz JR, Rocchetta H, Asawanonda P, Luo F, Thomas JH

BACKGROUND: Scalp seborrheic dermatitis and dandruff (SD/D) are chronic conditions requiring long-term treatment. There is a common belief that patients frequently experience decreasing benefits over time when using a single product. This physiologic accommodation is termed tachyphylaxis. AIM: To systematically investigate the anecdotal belief that tachyphylaxis occurs in long-term treatment of SD/D using quantitative clinical assessments. METHODS: An international questionnaire completed by 722 dermatologists assessed the belief of tachyphylaxis incidence with pyrithione zinc (PTZ)-based shampoos, time course, occurrence relative to active ingredients, and effect of switching products. Two double-blind, randomized, clinical evaluations were conducted, 24- and 48-week studies, whereby a 1% PTZ shampoo, a 2% PTZ shampoo, or a matched placebo control shampoo was used by each subject for the duration of the study. Dermatologists assessed the adherent scalp flaking (scale of 0-10) at baseline and at specified intervals. RESULTS: Sixty-four per cent of responding dermatologists believed tachyphylaxis occurred with PTZ products, and most felt that tachyphylaxis occurred within 3 months of use. Evaluation of mean treatment responses vs. placebo and individual responses as a function of study duration showed a consistent benefit for all products at all time points; therefore, no evidence for tachyphylaxis was found (within 48 weeks of treatment). CONCLUSION: No evidence for tachyphylaxis in SD/D treatment by PTZ-based shampoos was found. Compliance could explain the decreasing response rate seen over time; the solution is to choose an affordable therapeutic product that is effective long term without cosmetic trade-offs.

PMID: 19126058 [PubMed - indexed for MEDLINE]