Low concentration dithranol and coal tar (Psorin) in psoriasis: a comparison with alcoholic coal tar extract and allantoin (Alphosyl).

Psoriasis is difficult to manage in general practice, mainly because the standard treatments produce side effects, or are ineffective in both the short and long term. In recent years, the main topical therapies have included extracts of coal tar or dithranol. In a six-week within-patient trial, 23 patients applied two different treatments to the left and right halves of their bodies. A new preparation (Psorin, Thames Laboratories), containing relatively low concentrations of dithranol and crude coal tar, was significantly more effective and more acceptable than a refined alcoholic extract of coal tar with allantoin (Alphosyl, Stafford Miller Ltd).