Delta-9-tetrahydrocannabinol: localization in body fat.

[(14)C]Delta(9)-Tetrahydrocannabinol (Delta(9)THC) was injected subcutaneously in rats every day for 1 to 26 days. Concentrations of Delta(9)THC and its metabolites, 11-hydroxytetrahydrocannabinol and 8,11-dihydroxytetrahydrocannabinol, were determined in various tissues. After a single injection, the concentration of Delta(9)THC in fat was ten times greater than in any other tissue examined, and persisted in this tissue for 2 weeks. With repeated injection, Delta(9)THC and its metabolites accumulated in fat and brain.