Subjective, psychomotor, and physiological effects of cumulative doses of mixed-action opioids in healthy volunteers.

Rationale: Conducting complete dose-response evaluations of multiple drugs in a single within-subjects experiment is very time-consuming when a complete session is required for evaluation of each dose.

Objective: To evaluate a within-session cumulative-dosing procedure as a potentially efficient method for conducting dose-response evaluations of mixed-action opioids.

Methods: Fifteen healthy volunteers received intravenous injections of saline, butorphanol, nalbuphine, pentazocine, or morphine in a randomized, double-blind, crossover design.