Topical 8-methoxypsoralen photochemotherapy of psoriasis: a clinical study.

Topical psoralen plus UV-A irradiation (topical PUVA) was re-evaluated with regard to the timing of UV-A exposure. Symmetrical lesions of fifteen patients with psoriasis were treated with topical PUVA. One side was exposed to UV-A 2 h after topical application of I% 8-methoxypsoralen (2-h interval therapy), while the other side was exposed to the same dose of UV-A within 5 min of the topical application (non-interval therapy). Both regimens were effective. The non-interval therapy was preferred in one case, the 2-hour interval was preferred in three cases, and there was no clear difference in the other eleven cases. There was less tendency to burning with the non-interval therapy, and our study suggests that this is a useful regimen in the out-patient treatment of psoriasis.