Figure 60-8 Remifentanil is the newest potent opioid available for the care of neonates. Note that unlike virtually all other medications, the half-life is shorter in neonates than in older children, probably because of remifentanil's elimination by nonspecific plasma and tissue esterases, as well as the larger volume of distribution in neonates. The importance of this observation is that developmental immaturity of liver and renal function does not affect remifentanil pharmacokinetics. Because this was a single-bolus administration study, it is not clear whether similar pharmacokinetics would follow a long continuous infusion. (Data abstracted from Ross AK, Davis PJ, et al: Pharmacokinetics of remifentanil in anesthetized pediatric patients undergoing elective surgery or diagnostic procedures. Anesth Analg 93:1393–1401, 2001.)