Utility functions constructed from the pharmacokinetic and pharmacodynamic analysis of the volunteer data. Utility = the difference in probability of analgesia and probability of respiratory depression. The utility functions are a function of the biophase oliceridine or morphine concentration. In blue, the oliceridine utility function (blue continuous line is the mean with blue 95% CI band). In orange, the morphine utility function (continuous lines are the mean with orange 95% CI band).