Concentration of 3H-8-methoxypsoralen and its metabolites in the rat lens and eye after a single oral administration.

Concentrations of 3H-8-methoxypsoralen (MOP), its lipid- and water-soluble metabolites, tritiated water, and an insoluble compound have been measured in rat serum, lens, and eye tissue by liquid scintillation, thin-layer chromatography, and other techniques. The radioactivity has been measured in albino and pigmented rats up to 1 week after medication, and 3H-8-MOP and metabolite concentrations have been measured in pigmented rats from 10 min to 24 hr after oral administration by stomach tube of a solution of 3H-8-MOP (1 mg/kg body weight). The animals were kept in the dark. The maximum 3H-8-MOP concentrations were seen 10 min after medication in all the organs examined. The concentrations (in microgram/kg) at 10 min, 2 hr, and 24 hr, respectively, after medication were: serum, 698, 55, and 0.8; lens, 11.3, 5.2, and 1.4; other eye tissue, 393, 23, and 2.5. Water soluble metabolites might accumulate in the lens, but the absolute concentration is small. There was no accumulation of metabolites in the other organs. The considerable amount of radioactivity still present in tissues 1 week after a single medication was a result of the formation of tritiated water from the degraded 3H-8-MOP.