A double-blind comparison of 0.1% dithranol in a 17% urea base (‘Psoradrate’) and base alone in the treatment of active chronic psoriasis

A preliminary double-blind controlled trial was carried out in 8 patients with active chronic psoriasis, whose lesions were more or less bilaterally symmetrical, to assess the efficacy of topical treatment with 0.1% dithranol in a specialized carbamide (17% urea) base. The trial preparation was applied twice daily to one side only over a period of 3 weeks, and lesions on the other side of the body were treated in a similar manner with the base alone. Assessments of clinical improvement, based on severity rating scores, were carried out at weekly intervals. The results showed that, although use of the base alone led to some improvement, the preparation including dithranol was twice as effective, and this finding was supported by the patients' preference. It was easy to apply and remove and was well tolerated, the only side-effects reported being stinging and/or smarting.