Plasma levels of 8-methoxypsoralen after bath-PUVA for psoriasis: relationship to disease severity.

Plasma levels of 8-methoxypsoralen (8-MOP) were determined by high-pressure liquid chromatography in 19 patients with psoriasis who were receiving bath-PUVA treatment, at different time points after the psoralen bath. The levels of 8-MOP varied between < 5 ng/ml (lower limit of detection) and 34 ng/ml, and we found a relationship between the plasma psoralen levels and the severity of the disease.