Non-steroid creams in the treatment of chronic psoriasis in general practice: Comparison of a 0.1% dithranol and urea cream with a refined coal tar cream

Summary

A single-blind, multi-centre study was carried out to compare two non-steroid therapies in the treatment of 51 patients with mild to moderate psoriasis. The study was designed as a within-patient comparison in which one side of the patient was treated with 0.1% dithranol in a 17% urea cream base and the other side was treated with a cream containing 5% refined coal tar extract and 2% allantoin, the creams being randomly allocated to right and left sides. Treatment lasted for 6 weeks and the investigators' assessments were made every 2 weeks. The results showed that the 0.1% dithranol/urea cream was significantly more effective than the refined coal tar cream in clearing psoriasis. After 6 weeks, a 67% mean overall improvement in psoriasis was obtained with the dithranol/urea as against 47% for the tar-based cream (p=0.01). The 0.1% dithranol/urea cream produced significantly greater reductions in scaling and redness of the psoriasis lesions than the 5% refined coal tar extract/allantoin product. The 0.1% dithranol/urea cream was preferred by the vast majority of patients because of its greater effectiveness, although initially it inevitably caused more minor irritant side-effects.

Key Words::

• Dithranol
• urea
• coal tar
• dermatologic agents
• psoriasis