Table 2. Substitution Studies of Efavirenz in Rats Trained for Discrimination of Different Drugs of Abuse.

Training drug	Test compound	Dose (mg/kg)	N testa	%DARb	Rate (responses/s)c
LSD	Vehicle	0	8/8	13.6±12.4	0.675±0.107
LSD	LSD	0.1	8/8	86.4±10.2	0.703±0.122
LSD	Efavirenz	30	5/8	62.8±21.3d	0.294±0.106e
Efavirenz	Vehicle	0	6/6	16.7±16.7	0.447±0.071
Efavirenz	Efavirenz	18	6/6	77.1±16.6	0.372±0.060
Efavirenz	LSD	0.1	6/6	65.2±20.7d	0.336±0.051
MDMA	Vehicle	0	9/9	1.0±1.0	0.672±0.032
MDMA	MDMA	1.5	9/9	100.0±0.0	0.725±0.068
MDMA	Efavirenz	30	5/9	40.0±24.5d	0.189±0.064e
Cocaine	Vehicle	0	6/6	0.0±0.0	0.596±0.072
Cocaine	Cocaine	10	6/6	83.3±16.7	0.995±0.243
Cocaine	Efavirenz	30	5/6	21.8±19.6	0.201±0.053e
Carisoprodol	Vehicle	0	9/9	14.7±9.9	0.445±0.052
Carisoprodol	Carisoprodol	100	9/9	100.0±0.0	0.718±0.101
Carisoprodol	Efavirenz	18	7/9	25.2±13.9	0.262±0.059e

^aOf the total rats tested, the number receiving at least one reinforcer that could be used in the assessment of substitution.

^bMean percent of responses (%DAR) on the training drug lever (±SEM) at the dose yielding the greatest substitution.

^cRate of responding (lever responses per second±SEM).

^dValues that reached the criteria for substitution (⩾40% drug-appropriate responding and not statistically different from the training drug at P<0.05).

^eSignificantly different from vehicle control at P<0.05 (single degree of freedom F-test within one-way ANOVA).