Remifentanil
Remifentanil. Ultra-short-acting synthetic μ-opioid agonist — esterase-cleared (not CYP) giving ~3-4 min context-sensitive half-time even after… IV half-life 0.2 h.
Ultra-short-acting synthetic μ-opioid agonist — esterase-cleared (not CYP) giving ~3-4 min context-sensitive half-time even after long infusions. IV-only continuous infusion for surgical anesthesia. Rapid offset means no opioid-tolerance build-up across surgery.
PK: THE RECORD HAS SANDED OFF A SIGNATURE IT SHOULD PRESERVE. Its own reference states "Total clearance (250-300 l/h) ... approximately three to four times greater than the normal hepatic blood flow" — the fact that makes this drug what it is — and the stored pair implies 131 L/h, HALF OF IT. The volume is an in-range pick rather than a verbatim value (0.39 L/kg gives 27.3; another source offers "25-40 l"), and the parameterisation PRESERVES ONSET AND OFFSET WHILE SACRIFICING EXPOSURE TWO-FOLD. FOR AN AGENT GIVEN BY INFUSION AND TITRATED TO EFFECT THAT IS ARGUABLY THE RIGHT TRADE, AND IT WAS ENTIRELY UNDOCUMENTED; it is now declared rather than corrected. TWO SEPARATE ITEMS ARE LOGGED RATHER THAN FIXED: the stored typical dose of 0.25 mcg is A mcg/kg/min INFUSION RATE AND NOT A DOSE AT ALL, which the schema cannot express; and its phantom absorption constant on an intravenous route is removed here. EFFECT COMPARTMENT: THE OLD VALUE WAS HONEST AND STILL WRONG FOR THIS PURPOSE. It was fitted, verbatim, and CORRECTLY LABELLED AS DOG — one of only eleven records in the whole catalogue that ever declared a non-human species, which is a credit to whoever authored it — but the human measurement exists and is nearly twice as fast, in a direct head-to-head that also supplies the alfentanil value corrected in the same pass. The species flag is removed with the animal number.
Pharmacokinetics
- IV — t½ 10 min · F 100% · Vd 30 L
Sources: PMID:7902033, PMID:8638836