Investigations on the interaction between cyproheptadine and amphetamine.

The effect of cyproheptadine (CPH) given in doses of 1.25 and 5 mg/kg intraperitoneally one hour before administration of D-(+)-amphetamine (AMPH) 5 mg/kg subcutaneously was studied. A moderate increase was observed in the intensity of amphetamine-induced stereotypy and a significant rise in the number of rearings after premedication with CPH 5 mg/kg. In pharmacokinetic investigations the serum level of AMPH was found to be decreased in the animals after CPH premedication. The biological half-time of AMPH in the blood was reduced after premedication with CPH 5 mg/kg. On the other hand, the level of amphetamine rose in the brain following premedication with CPH in both doses. These results suggest that the rise in brain AMPH level could be responsible for intensification of AMPH effects induced by CPH premedication.