Figure 11-16 A simulation of the time necessary to achieve a 50% decrease in drug concentration in the blood (or plasma) after variable-length intravenous infusions of remifentanil, fentanyl, alfentanil, and sufentanil. (From Egan TD, Lemmens HJ, Fiset P, et al: The pharmacokinetics of the new short-acting opioid remifentanil (GI87084B) in healthy adult male volunteers. Anesthesiology 79:881–892, 1993.)