Background: Tachyphylaxis, defined as a rapidly decreasing response to a physiologically active agent after administration of a few doses, can be well demonstrated in the experimental setting. However, tachyphylaxis in the clinical setting lacks clear demonstration. Objective: Our purpose was to identify dermatologists' perception of the clinical incidence of tachyphylaxis and then design a prospective study that would estimate the clinical incidence of tachyphylaxis. Methods: Clinical and academic dermatologists completed a survey questionnaire about the incidence of tachyphylaxis and the time course to its occurrence. Subjects with plaque psoriasis applied topical corticosteroid twice daily for 12 weeks to their plaques, leaving an isolated plaque untreated for comparison. Plaques were evaluated every 2 weeks. By means of a 9-point scale, an end point for clinical detection of tachyphylaxis was defined as 'an increase in plaque elevation of at least 2 occurring after a detectable decrease in plaque elevation with topical steroid.' Results: The survey found that 57% of dermatologists perceived that tachyphylaxis occurred after 8 week of therapy with topical corticosteroid. In the 12-week clinical study, none of 32 patients exhibited detectable signs of tachyphylaxis. Conclusion: What accounts for the commonly held belief of tachyphylaxis in the clinical setting may be related to the therapeutic efficacy of topical corticosteroids. Failure of topical corticosteroids to clear psoriasis after an initial improvement may give the impression of tachyphylaxis. The common clinica perception of tachyphylaxis may also be related to issues of compliance outside a study setting or a psoriasis flare unrelated to therapy.
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