Fig. 1. (  A ) Effect of placebo on 0.2 mg buprenorphine–induced respiratory depression. Values are the mean values ± SEM (n = 8) of the 1-min averages of individual subjects. (  B ) Influence of 2 mg naloxone given over 30 min on 0.2 mg buprenorphine–induced respiratory depression (  open circles ) in one subject.  Gray field in the background is the result of the placebo group. (  C ) Influence of 6 mg naloxone given over 30 min on 0.2 mg buprenorphine–induced respiratory depression (  open circles ) in one subject.  Gray field in the background is the result of the placebo group.  Light gray dots = buprenorphine infusion;  dark gray dots = naloxone infusion.