[Remifentanil]

Remifentanil is a potent mu-opioid receptor agonist and has some unique pharmacokinetic characteristics compared to other anilidopiperidine opioids (e.g. fentanyl, alfentanil, and sufentanil). As remifentanil is metabolised rapidly by nonspecific esterases that are widespread throughout the plasma and tissuses, its duration of action is very short. It is cleared very rapidly, and its clearance is not affected by renal and hepatic function. The context-sensitive half-time of remifentanil remains consistently short, even after administration for a long time. Consequently, emergence is quick even after anesthesia of long duration. As other piperidine opioids, remifentnil has some adverse effects such as respiratory depression, muscle rigidity, bradycardia, and nausea as well as vomiting. Because of the rapid dissipation of analgesic effect following remifentanil discontinuation, postoperative analgesia should be provided before or soon after anesthesia using longer-acting opioid analgesics, non-opioid analgesics, or local as well as regional anesthesia.