Benzodiazepine self-administration in rhesus monkeys: estazolam, flurazepam and lorazepam.

The ability of three benzodiazepines to maintain self-administration behavior was studied in rhesus monkeys using a substitution procedure. Lever-press responding was maintained in six monkeys under a fixed-ratio schedule of IV pentobarbital delivery in daily sessions of 3 hr duration. Each of several doses of flurazepam, lorazepam and estazolam as well as saline and vehicle was periodically substituted for 4-13 consecutive sessions. Between dose or vehicle substitutions, responding was maintained by pentobarbital. All six monkeys self-administered flurazepam above vehicle or saline levels. In addition four of five monkeys tested with lorazepam and four of six tested with estazolam self-administered at least one dose of drug above control levels. These results indicate that self-administration performance can be reliably maintained in rhesus monkeys by certain benzodiazepines under appropriate experimental conditions.