Phototoxic effect and plasma levels of 8-MOP

In six healthy volunteers the 8-methoxypsoralen (8-MOP) plasma levels have been determined by high resolution liquid chromatography (HPLC) respectively 15, 30, 60, 90, 120, 150 and 180 minutes after the oral intake of an oral formulation of the drug (0.6 mg/kg b.w.). In order to evaluate the cutaneous photosensitivity, each subject has been exposed to UVA (wavelength 320-400-nm) at 15, 30, 60, 120, 150 minutes intervals from the 8-MOP intake. During each UVA exposure eight areas (1 cm in diameter) received 1, 2, 3, 4, 5, 6, 7 and 8 J/cm2. The results show that the lowest MPD is achieved from 30 and 60 minutes after the highest plasma level of the 8-MOP.