Influenced of food on the kinetics of 8-methoxypsoralen in serum and suction blister fluid in psoriatic patients.

The influence of food on the kinetics of 8-methoxypsoralen (8-MOP) in serum and suction blister fluid was evaluated in a cross-over study in 19 psoriatic patients under PUVA treatment. The peak serum concentration of 8-MOP was reached 1.5 h after ingestion on an empty stomach, and in suction blister fluid the maximum concentration was already present in the first sample taken after 2 h, the time when UVA radiation was given. The postprandial kinetics of 8-MOP in serum and suction blister fluid differed, the highest levels being reached, respectively, at 2.4 and 3 h after intake, i.e. in both body fluids after irradiation had started. The side effects of 8-MOP, such as nausea and dizziness, in the two groups were similar. The present results indicate that to optimize the therapeutic effect of PUVA in individual patients, 8-MOP should be given on an empty stomach.