Remifentanil

Remifentanil is a short-acting opioid analgesic drug, given to patients during surgery to relieve pain and as a complement to an anaesthetic. It is administered in the form remifentanil hydrochloride and usually given as an intravenous infusion in doses ranging from 0.1mcg/kg/min to 0.5mcg/kg/min. It is a specific mu-receptor agonist. Thus causing a reduction in sympathetic nervous system tone, respiratory depression, and analgesia. Unlike other synthetic opioids, its clearance is dependent on non-specific plasma esterases. This means that accumulation is not a problem with remifentanil and it's context-sensitive half time after a 4 hour infusion is 4 minutes. It is metabolised to a compound which has 1/1600 the potency of the parent compound. The drug's effects include a dose dependent decrease in heart rate and arterial pressure; and decrease in respiratory rate and tidal volume (muscle rigidity is sometimes noted).

Reference

Abbott Laboratories, Chicago, IL "'Ultiva"' package insert