Objective: Evaluate and compare the efficacy, safety, and tolerability of coal tar (10% LCD, liquor carbonis detergens), with betamethasone valerate in the therapy of large plaque-type psoriasis.
Material and Method: Patients with stable, mild to moderate plaque psoriasis at the Department of Medicine, Lerdsin General Hospital, Bangkok, Thailand were randomized for treatment with either coal tar (10% LCD) cream or betamethasone valerate cream (0.1%). All patients entered a 2 week wash-out period followed by the creams being applied twice daily until completion at 6 weeks. The patient severity of psoriasis was assessed using the modified Psoriasis Area and Severity Index (PASI) score at baseline and after 2, 4, and 6 weeks of treatment.
Result: At the end of the trial, the mean reduction of the PASI score from baseline was 38.39% with the coal tar group and 69.36% with the betamethasone valerate group. The mean percentage of the PASI score reduction was statistically significant in both groups but the betamethasone valerate group was significantly superior to the coal tar group. Both drugs’ adverse effects were limited to mild irritation localized to the skin without systemic side effects. The Betamethasone valerate cream was safe, effective, and well-tolerated while the coal tar cream was described as messy, malodorous, and with a tendency to staining clothes.
Conclusion: The investigator’s overall assessment of the treatment response at completion of the trial demonstrated that the betamethasone valerate group achieved significantly greater clearance and marked improvement compared with the coal tar group.

Keywords: Coal tar, Betamethasone valerate, Plaque type psoriasis