Treatment of resistant psoriasis with oral 8-methoxypsoralen and longwave ultraviolet light (PUVA). A treatment schedule and a follow-up study.

Thirty-one patients with resistant psoriasis were treated with 8-methoxypsoralen orally, followed by irradiation with long-wave ultraviolet light (PUVA). The initial irradiance was 1.4 Joule/cm2, increased by 0.5 Joule/cm2 at the following exposures, to a maximum of 4.2 Joule/cm2. The 8-methoxypsoralen dosage was approximately 0.5 mg/kg body weight. In 17 patients psoriasis cleared completely after 10.8 +/- 3.4 exposures (mean +/- S.D.). In 12 patients the healing was almost complete after 14.5 +/- 5.8 exposures. Adverse effects were negligible. After clearing, the patients were followed without further therapy. Psoriasis recurred in approximately half of those patients followed for more than 2 months, on average 5 weeks after cessation of treatment. PUVA is an effective and agreeable therapy for recalcitrant psoriasis. Further studies must be carried out to evaluate the risks of a long-term treatment.