Determination of 8-methoxypsoralen kinetics : a relevant factor in the treatment of psoriasis by psoralen plus ultraviolet A therapy

: We compared the efficacy of psoralen plus ultraviolet A (UVA) therapy in 2 groups of psoriatic patients: a group of patients treated by a protocol adapted to the results of 8-methoxypsoralen (8-MOP) plasma kinetics (kinetics group) versus a control group of patients treated according to Pathak's standard protocol (UVA exposure 2 h after oral administration of a dose of 8-MOP equal to 0.6 mg/kg) (control group). The 8-MOP plasma kinetics were determined before the beginning of treatment. The parameter for comparison is the rapidity of clearing, taking into account the number of UVA exposures and UVA joules received. The analysis of the results observed show a 26.6% decrease in the number of UVA exposures and a 38.4% decrease in the dose of UVA received. These results are confirmed by the individual analysis of the rapidity with which the clearance of psoriatic lesions was obtained in patients who were treated with the standard PUVA protocol during the first attack and with the adapted protocol during the second attack.