[Is remifentanil an ideal opioid for anesthesiologic management in the 21st century?]

Current trends toward outpatient surgery and closed loop computer controlled drug administration have created a demand for short acting anaesthetic agents. Such agents not only provide the anaesthetist with rapid patient recovery after completion of the procedure, but also with almost immediate intra-operative control over the anaesthetic state of the patient. Shorter acting anaesthetic agents are being developed in several therapeutic areas including volatile anaesthetics, neuromuscular blockers as well as injectable anaesthetics. In the injectable anaesthetic area, propofol has been introduced and offers some significant advantages over the previously existing induction agents. Remifentanil is a novel member in the family of the 4-anilidopiperidine opioid analgesics which also include the traditional agents fentanyl, alfentanil, and sufentanil. Remifentanil undergoes widespread extrahepatic metabolism by blood and tissue nonspecific esterases, resulting in an extremely rapid clearance. Because of its unique metabolic pathway among this group of drugs, remifentanil represents a new pharmacokinetic class of opioids which is named esterase metabolised opioid (EMO). Rapid biotransformation to minimally active metabolites results in short and predictable duration of action with no accumulation of effect on repeated dosing or with continuous infusion. Clinical experiences presented so far indicate that remifentanil can be safely administered in different anaesthetic regimens as well as in the great variety of patients including children and patients with renal, hepatic or cardiovascular diseases. However, its use also presents the anaesthetist with a significant challenge. If remifentanil is the only opioid analgesic administered during anaesthesia, it must be remembered that shortly after the end of the surgical procedure, the patient will not benefit from opioid-based analgesia. This problem must be addressed if remifentanil is to be used for procedures associated with significant postoperative pain. Reducing the infusion rate of remifentanil to analgesic doses suitable for the postoperative pain management or immediate administration of longer acting opioids at the end of anaesthesia might solve this problem. At present it is difficult to predict precisely the future ranking of remifentanil. However, the unique pharmacokinetic profile of remifentanil should make it useful in the various surgical settings and in all circumstances where precise control over the analgesic state are desirable.