Figure 4.

Correlation between plasma (+)-phenmetrazine levels and percent cocaine-appropriate responding as a function of time after (+)-phenmetrazine administration in rhesus monkeys (n=5). Ordinates: percent cocaine-appropriate responding. Abscissae: plasma (+)-phenmetrazine levels in nM (log scale). Different symbols represent different doses of (+)-phenmetrazine in individual monkeys. In the presence of a significant correlation, the effective concentration, in nM, that produced 50% cocaine-appropriate responding (EC50) value was calculated using linear regression. Each panel shows data for a different time after (+)-phenmetrazine administration, and this time is shown in the upper left corner of each panel.