Distribution of 3H-8-MOP and its metabolites in rat organs after a single oral administration.

Concentrations of 3H-8-methoxypsoralen (MOP), its lipid- and water soluble metabolites and tritiated water have been measured in rat serum, liver, kidney, and skin, using liquid scintillation, thin-layer chromatography and other techniques. Radioactivity in whole blood, plasma, ovary, adrenals, and pancreas has also been measured. The radioactivity has been measured up to 1 week after medication, whilst 3H-8-MOP and metabolite concentrations have been measured from 10 min to 24 hr after medication with a single dose of 1 mg 3H-8-MOP in solution/kg bodyweight. Maximum 8-MOP concentrations were seen from 10 to 30 min after dosing. The concentrations in microgram/kg 10 min, 2 hr, and 24 hr after medication were as follows: serum--686, 57, 2.1; liver--489, 45, 3.3; kidney--1708, 139, 4.3; and skin--55, 16, 3.8. The concentrations of water soluble metabolites were very high in the liver and only slightly lower in the kidney. The concentrations of these metabolites might accumulate after doses repeated 4 times a week. 3H-8-MOP and its other metabolites would not show similar accumulation. Most of the radioactivity present after 1 week is due to tritiated water.