Treatment of chronic plaque psoriasis with dithranol and urea creams: a double-blind study.

Stable cream formulations containing 0.1% or 0.2% dithranol in a 17% urea base have been developed. A double-blind comparative trial in 20 out-patients showed that over a 6-week treatment period the 0.2% dithranol and urea cream was significantly more effective (p less than 0.01) than the 0.1% dithranol and urea cream in clearing chronic plaque psoriasis. The 0.2% dithranol/urea cream was accompanied by a higher incidence of minor, irritant side-effects, but was still well accepted by patients for use at home. The availability of differing strengths of dithranol and urea cream enables practitioners to tailor dithranol treatment in accordance with the individual patient's clinical response.