Abstract
The relationships between drug dosage per injection and response rate, and drug dosage per injection and total daily drug intake were ascertained in Rhesus monkeys which self-administered cocaine, pipradrol, methylphenidate and phenmetrazine intravenously. The study demonstrated the monkeys would self-administer all of these compounds over a wide range of dosages. Furthermore, the magnitude of reinforcement, i.e., dosage per injection, and the rate of responding in self-administering these compounds were inversely related. However, total daily drug intake was independent of the dosage per injection over a wide range of dosages. The results indicate that either the subjects can compensate for large changes in unit dosage so that daily drug intake remains stable or that a direct effect of these compounds functions in limiting their self-administration.