Reinforcing properties of some local anesthetics in rhesus monkeys.

The reinforcing properties of several local anesthetics were determined in rhesus monkeys experienced in the intravenous self-injection of cocaine. Intravenous procaine and, occasionally, tetracaine maintained response rates higher than did vehicle injections in most monkeys. In contrast, lidocaine, procainamide and diethylaminoethanol (a metabolite of procaine) failed to maintain responding resulting in their intravenous delivery. These results demonstrate that not all local anesthetics are positive reinforcers in the rhesus monkey when delivered intravenously. Furthermore, the reinforcing properties of procaine probably cannot be attributed to its metabolite diethylaminoethanol. The data suggest that short-acting, esteratic local anesthetics are most likely to have reinforcing properties in the rhesus monkey.