Narcotic-reinforced responding: a rapid evaluation procedure.

Rhesus monkeys were conditioned to lever press for intravenous injections of codeine. The self-injection behavior was brought under the control of a schedule of drug delivery and access to the codeine schedule was made available twice each day. Subsequently, a variety of doses of codeine and saline were compared to the dose used to condition and maintain self-injection responding. Each change in drug condition was maintained for only a single experimental session. The procedure is recommended for rapid evaluation of drugs for their capacity to reinforce self-injection behavior.