A Double-Blind Study Comparing Oleum Horwathiensis with Placebo in the Treatment of Psoriasis

The efficacy and tolerability of topically applied oleum horwathiensis were evaluated in a double-blind, placebo-controlled study of 42 patients with chronic stable psoriasis. Both groups of patients, 19 receiving oleum horwathiensis treatment and 23 receiving placebo treatment for 12 weeks, showed clinically significant effects of treatment. Oleum horwathiensis was more effective than placebo throughout the treatment period but the difference was not statistically significant at any time. No changes in laboratory values attributable to treatment were recorded. The symptoms of the oleum horwathiensis-treated group continued to be less severe than those of the placebo-treated group throughout the 12 weeks of follow-up. The follow-up period, however, occurred partly during the summer and since the clinical status of the patients may have been affected by climate the difference between the treatment groups was not analysed statistically. The tolerability and cosmetic acceptance of oleum horwathiensis were remarkably good, and good clinical efficacy in scalp lesions – which was not the subject of this study – was spontaneously reported by several patients.