Opioid · Analgesic
Remifentanil (Ultiva)
Also called Ultiva
Indications
- Analgesia during induction and maintenance of general anesthesia (label)
- Continued analgesia into the immediate postoperative period in PACU or ICU, under anesthesia supervision (label)
- Analgesic component of monitored anesthesia care (label)
- Analgesia-based sedation of ventilated ICU adults for up to 3 days (EU label; off-label in the US)
- Labor analgesia by IV PCA when neuraxial analgesia is not possible (off-label; the US label advises against use in labor)
Dosing
Remifentanil drip card and mL/h converterStart: ICU analgesia-sedation (EU label): 0.1–0.15 mcg/kg/min, no bolus. After surgery, under anesthesia supervision (US label): 0.1 mcg/kg/min. Obesity: dose by ideal body weight
Mechanism of action
Remifentanil is a selective μ-opioid receptor agonist of the 4-anilidopiperidine (fentanyl) family. Activated Gi/o proteins inhibit adenylyl cyclase, open GIRK potassium channels and close N-type calcium channels, so dorsal horn and brainstem neurons release less transmitter and pain transmission is blocked; in the brainstem respiratory network the same action depresses breathing. Nonspecific blood and tissue esterases hydrolyze its methyl ester side chain, so the effect ends within minutes however long the infusion has run.
Pharmacology
- CNS: dose-related analgesia and sedation, analgesic at 0.05–0.1 mcg/kg/min (label); synergy with propofol, volatile agents and benzodiazepines
- Respiratory: dose-related depression and apnea; spontaneous breathing returns within minutes of stopping
- Cardiovascular: dose-dependent bradycardia and hypotension; no histamine release (label)
- Musculoskeletal: chest wall rigidity after boluses over 1 mcg/kg or rates over 0.1 mcg/kg/min, much less after a hypnotic or neuromuscular blocker (label)
- Other: nausea, shivering and pruritus; acute tolerance and opioid-induced hyperalgesia after high-dose infusions (label; Fletcher 2014)
Pharmacokinetics
| Onset | About 1 min (label) |
|---|---|
| Context-sensitive half-time | 3.2 min after a 3-h infusion vs 47 min for alfentanil (Kapila 1995); 3–6 min whatever the duration (label) |
| Half-life | Effective 3–10 min; terminal 10–20 min; recovery within 5–10 min (label) |
| Distribution | Vd about 100 mL/kg initially, 350 mL/kg at steady state (label) |
| Protein binding | About 70%, mostly α₁-acid glycoprotein (label) |
| Metabolism | Over 95% by nonspecific blood and tissue esterases (not plasma cholinesterase) to remifentanil acid, 1/4,600 as potent (label) |
| Clearance | About 40 mL/kg/min; 25% lower over 65, 20% lower on hypothermic bypass (label) |
| Elimination | The acid leaves in urine, half-life 90 min, up to 30 h in anephric patients (label) |
| Organ failure | Unchanged in kidney or liver failure; obese patients are dosed by ideal body weight (label) |
Chemistry
- A 4-anilidopiperidine like fentanyl with a methyl ester side chain, the esterase target; C₂₀H₂₈N₂O₅·HCl, MW 412.9; achiral (label)
- pKa 7.07, so about two-thirds is un-ionized at pH 7.4; octanol:water partition coefficient 17.9, far lower than fentanyl's (label)
- Lyophilized 1, 2 or 5 mg vials with glycine and HCl (pH 2.5–3.5 at 1 mg/mL), diluted to 20–250 mcg/mL and stable 24 h at room temperature (label)
- The glycine rules out epidural and intrathecal use (label)
Adverse effects and cautions
In the one-pagers
Other opioid drugs
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Sources
- FDA label: Ultiva (Mylan, 2025)
- EU SmPC: Ultiva
- Kapila 1995 (context-sensitive half-time)
- Fletcher 2014 (remifentanil hyperalgesia)
For education and exam preparation only. Follow your institution’s protocols. Typical adult values for study. Follow the order, the label and your institution's protocols.