Table 3

Nicotine discrimination: ED50 values in milligrams per kilogram with 95% confidence limits (CL) in parentheses of the drugs studied in generalization tests

DrugED50 (95% CL)
% GeneralizationResponse Rates
Amphetamine1.000.163-150 0.871.751.701.62
Cocaine9.82.03-150 5.814.915.617.9

ED50 values with 95% CL were calculated from dose-response functions of the drugs in water, 0.25-CAFF, and 1.0-CAFF groups as shown in Figs. 5 and 6. Data from dose-response functions were treated quantitatively. ED50 values of nicotine-appropriate responses were calculated from the ascending portion of the dose-response function of nicotine (0.025–0.4 mg/kg) amphetamine (0.03–1.7 mg/kg) and cocaine (0.3–13 mg/kg). ED50 values of changes in rates of responding were calculated from the descending portion of dose-response function of nicotine (0.2–0.8 mg/kg), amphetamine (0.3–3.0 mg/kg) and cocaine (3.0–17.0 mg/kg). Each ED50 value reflects a dose of a drug in milligrams per kilogram predicted to produce 50% nicotine-appropriate responses (% generalization) or reduce rates of responding to 50% of the individual baseline level of responding.

  • 3-150P < .05 vs. water-drinking group.