Treatment of atopic dermatitis with antihistamines: lessons from a single-patient, randomized clinical trial.

BACKGROUND Single-patient randomized clinical trials (RCTs) can be utilized to maintain methodologic precision in the analysis of treatment effect in individual patients. We describe the results of a single-patient RCT in a patient with atopic dermatitis and review practical considerations regarding the use of antihistamines. METHODS Using double-blind, crossover techniques, the patient was randomly allocated to four 2-week treatment periods with the following regimens: chlorpheniramine, 8 mg twice daily; chlorpheniramine, 12 mg twice daily; terfenadine, 120 mg twice daily; and placebo (phase 1). The drug that produced superior results from phase 1 (chlorpheniramine, 8 mg) was subsequently compared with astemizole, 10 mg/d, during phase 2, consisting of four 4-week, double-blind, crossover trial periods with random allocation of study drugs. Daily symptom scores, as well as end of treatment period summary impressions by patient and investigator, were analyzed. RESULTS In both phases, chlorpheniramine produced the most noticeable positive therapeutic effect on the patient's mild but most disturbing symptoms (pruritus and eye irritation) associated with atopic dermatitis. Drowsiness was reported with chlorpheniramine. Tolerance to this side effect, however, developed quickly. CONCLUSIONS A single-patient RCT with different antihistamines in a patient with chronic atopic dermatitis was a useful tool in achieving a favorable balance among efficacy, toxicity, and cost of therapy.