Drug Evaluation Central & Peripheral Nervous Systems: Remifentanil: an opioid metabolised by esterases

Abstract

Remifentanil is a new opioid metabolised by circulating and tissue esterases. It is therefore extremely short-acting, and it does not depend on redistribution for terminating its effects as do the other ‘short-acting’ opioids. The kinetics of remifentanil have been examined in detail and these studies have revealed that remifentanil dosing does not need to be adjusted for the presence of hepatic or renal dysfunction. Although its pharmacokinetic profile is similar in elderly persons, the required doses are lower in the elderly due to an increase in pharmacodynamic response. The major metabolite of remifentanil is approximately three orders of magnitude less potent an opioid agonist and therefore does not produce clinically significant opioid effects even when remifentanil is given at high infusion rates for long periods of time. Many clinical trials employing remifentanil have now been completed. These demonstrate that remifentanil may be used as the opioid component in intravenous general anaesthesia for a wide variety of surgical procedures, and that the predicted rapid emergence from anaesthesia is indeed observed.