Effect of diamorphine, delta 9-tetrahydrocannabinol and ethanol on intravenous cocaine disposition.

The disposition of cocaine (1 mg kg-1) was altered by diamorphine (0.1 mg kg-1) and that of morphine (1 mg kg-1) was altered after their concurrent administration as a bolus i.v. injection to rats by cocaine, without any changes in the metabolism of the drugs. delta 9-Tetrahydrocannabinol (10 mg kg-1 i.p.) did not affect the cocaine disposition. Chronic ethanol treatment (2.5 g kg-1 orally twice daily for 16 days) produced a significantly higher brain-to-plasma cocaine concentration ratio than did saline as control, without any changes in cocaine metabolism.