TABLE 3

Observed and predicted discriminative stimulus effects of binary mixtures of cocaine and caffeine, MDPV and caffeine, and cocaine and MDPV

MixtureED50 (mg/kg; Cocaine Equivalents)Potency RatioPotency RatioPotency Ratio
PredictedObservedED20OBS / ED20PREDED50OBS / ED50PREDED80OBS / ED80PRED
Mean 
(95% CI)Mean
(95% CI)Mean
(95% CI)Mean
(95% CI)Mean
(95% CI)
Cocaine:Caffeine
 3:15.4 (4.0–7.4)4.7 (3.4–6.7)1.31 (0.77–1.85)0.92 (0.67–1.14)0.67 (0.52–0.82)+
 1:15.1 (3.7–7.0)3.8 (2.7–5.5)1.23 (0.82–1.64)0.78 (0.59–0.97)+0.52 (0.36–0.68)+
 1:34.9 (3.7–6.5)4.3 (3.3–5.7)1.60 (0.42–2.79)0.95 (0.61–1.28)0.67 (0.34–0.99)+
MDPV:Caffeine
 3:14.3 (3.2–5.9)4.9 (3.7–6.5)1.69 (1.00–2.38)1.20 (0.76–1.64)0.87 (0.60–1.15)
 1:14.4 (3.2–5.9)4.4 (3.3–5.8)1.52 (0.86–2.17)1.07 (0.69–1.44)0.76 (0.51–1.02)
 1:34.3 (3.1–5.8)4.4 (3.5–5.6)1.62 (1.03–2.21)+1.10 (0.73–1.46)0.76 (0.50–1.02)
Cocaine:MDPV
 3:14.3 (3.2–5.8)3.3 (2.3–4.9)1.12 (0.48–1.76)0.84 (0.46–1.23)0.67 (0.37–0.97)+
 1:14.3 (3.2–5.8)4.3 (3.1–5.9)1.37 (0.87–1.87)1.06 (0.63–1.49)0.82 (0.47–1.17)
 1:34.4 (3.3–5.9)3.5 (2.4– 4.9)1.25 (0.70–1.80)0.84 (0.54–1.13)0.60 (0.44–0.77)+
  • + Significant difference between observed and predicted ED20, ED50, or ED80 values for an additive interaction as defined by 95% confidence interval (CI) that does not include 1.