Measurement of the response of psoriasis to short-term application of anthralin.

Thirty-six patients with psoriasis were treated with short-term application of anthralin in three studies. (I) In thirteen patients 2% anthralin was applied daily to lesions on one arm for 60 min; (2) in ten patients 4% anthralin was applied daily to lesions on one-half of the body for 30 min; (3) in thirteen patients 2% anthralin was applied daily to lesions on one-half of the body for 30 min and the strength was increased to 4% and then 8% at intervals of 3 or more days, according to tolerance. Comparison was made with the response to conventional daily treatment with 0.05% to 1% anthralin. Progress was compared clinically by days to clearing, by measurements of plaque thickness with Harpenden calipers, by the frequency and severity of burning, and by patient preference. There was no significant difference in the times to clinical clearance between short-term and conventional anthralin treatments and the rate of decrease of plaque thickness was likewise similar. There was an excellent correspondence between time to reach half plaque thickness and the time for each plaque to clear clinically. There was increased burning with all the short-term treatments but the patients still preferred it. We conclude that short-term treatment with anthralin is as effective as continuous application, but that the increased burning is likely to limit its usefulness.