Tripelennamine and pentazocine alone and in combination: effects on interresponse-time-greater-than-t responding of rats.

The effects of tripelennamine (3, 6, 12, 18, and 24 mg/kg) and pentazocine (5, 10, 20, 30, and 40 mg/kg), given alone and in selected combinations, were determined in rats performing under an interresponse-time-greater-than-15-sec schedule of food delivery. Each drug alone produced statistically insignificant increases in response rates and statistically significant decreases in reinforcement rates. Combinations produced effects identical in direction to, and significantly greater than, those predicted by a simple additive model.