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PENTOBARBITAL SELF‐ADMINISTRATION IN RHESUS MONKEYS: DRUG CONCENTRATION AND FIXED‐RATIO SIZE INTERACTIONS
Author(s) -
Lemaire Gregory A.,
Meisch Richard A.
Publication year - 1984
Publication title -
journal of the experimental analysis of behavior
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.75
H-Index - 61
eISSN - 1938-3711
pISSN - 0022-5002
DOI - 10.1901/jeab.1984.42-37
Subject(s) - pentobarbital , drug , self administration , drug intoxication , drug administration , drug delivery , pharmacology , chemistry , medicine , anesthesia , organic chemistry
Performances of three rhesus monkeys were reinforced by the oral delivery of pentobarbital and studied as functions of fixed‐ratio size and drug concentration. Pentobarbital solutions and water were concurrently available on identical reinforcement schedules from separate liquid‐delivery systems during 3‐hour sessions. Under a fixed‐ratio 16 schedule of drug availability, a descending series of drug concentrations was tested (4, 2, 1, 0.5, 0.25, 0.125, and 0.0625 mg/ml, followed by a retest at 4 mg/ml). Partial concentration series beginning with the highest concentration were repeated with fixed‐ratios of 32 and 64, with a fixed‐ratio 128 for two monkeys, and with fixed‐ratio 256 for one. At each fixed‐ratio value, response rate and number of drug deliveries were inverted U‐shaped functions of pentobarbital concentration. Drug intake (mg/kg/session) increased directly with drug concentration. As the fixed‐ratio size was increased, the number of liquid deliveries decreased. For each drug concentration, when the numbers of drug deliveries at fixed‐ratios of 32, 64, and 128 responses were plotted as percentages of those obtained at fixed‐ratio 16, the following orderly relationship emerged: the higher the drug concentration, the less that drug deliveries were decreased by increases in fixed‐ratio size. This relationship indicates an increase in reinforcing efficacy with increases in pentobarbital concentration.