Erythromycin in Pityriasis Rosea

Abstract

Source: Sharma PK, Yadav TP, Gautam RK, et al. Erythromycin in pityriasis rosea: a double-blind, placebo-controlled clinical trial. J Am Acad Dermatol. 2000;42:241–244.The authors of this study assessed the efficacy of oral erythromycin for treating pityriasis rosea (PR). Between July 1996 and June 1998, 90 patients (65 males) with clinically diagnosed PR presenting to the dermatology outpatient department of a major hospital in New Delhi, India, were enrolled in a double-blind, placebo-controlled trial. Participants were alternately assigned to receive erythromycin stearate (250 mg q.i.d. for adults, 25–40 mg/kg/d divided q.i.d. for children) or placebo for 2 weeks. After initiating treatment, evaluations were conducted weekly for 6 weeks. Response was assessed 2 weeks after beginning treatment as follows: (1) complete response (ie, all lesions and erythema resolved and no new lesions present); (2) partial response (resolution of only some lesions, some new lesions present); or (3) no response (no regression of lesions, new lesions present).Forty-five subjects received erythromycin and 45 received placebo and no significant differences between groups were observed with respect to mean age at presentation (18 years), gender, or mean duration of lesions at presentation (approximately 11 days). Seventy-one percent of those receiving erythromycin and 67% receiving placebo had a history of respiratory symptoms preceding the eruption. A complete response was seen in 33 (73.3%) patients in the treatment group and in none of those in the control group (P < .0001). Four (8.8%) patients in the treatment group and 5 (11.1%) in the control group had a partial response while no response was observed in 8 (17.8%) subjects receiving erythromycin and 40 (88.9%) receiving placebo. The only side effects of erythromycin were mild nausea in 2 patients in the treatment group.There are a number of important questions about the study’s design that are not addressed in this report such as how many subjects were approached to participate, how many declined, and whether those who declined differ in any way from those who enrolled. Answers to these questions would clarify whether there was an inadvertent bias in patient selection that influenced the results. Concern about this possibility is raised by the observation that 72% of subjects in the present study were male, while past experience indicates a slight female preponderance.1,2 Who made the diagnosis of PR (eg, dermatologist vs another clinician)? The accuracy of diagnosis is particularly important since PR may be confused with secondary syphilis and VDRL results were not presented. Were subjects compliant with therapy and, therefore, can the effect observed be attributed to erythromycin? Finally, did all subjects return weekly and complete the entire study? Until such questions are answered and this study replicated it seems premature to treat PR with erythromycin.