Sufentanil
Sufentanil citrate
Also known as: Fastfen · Fentaientel · R-33800 · sufentanili citras · fentathienel citrate · sufentanyl citrate · sulfentanil citrate
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| As a pre-med | 3 micrograms/kg IV | IV | Single dose | — | 🌎 NA |
| For epidural analgesia | 0.7-1 micrograms/kg diluted to a volume of 0.26 mL/kg with sterile saline | Epidural | Single dose | 1-4 hours | 🌎 NA |
| Acute pain relief in an emergency | 0.75-2 micrograms/kg IV ; constant rate infusion of 1-2 micrograms/kg/hour | IV | CRI | — | 🌎 NA |
| For surgical pain | 5 micrograms/kg IV prior to a CRI. CRI (post-operative) of 0.1 micrograms/kg/hour | IV | CRI | 2-6 hours | 🌎 NA |
- As a pre-med: As a combination for induction: Sufentanil 3 micrograms/kg IV first, then diazepam or midazolam 0.2-0.5 mg IV.
- For epidural analgesia: Onset of action in 10-15 minutes.
- For surgical pain: Duration of effect: 2-6 hours.
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Acute pain relief in an emergency | 0.1-0.5 micrograms/kg IV ; constant rate infusion of 0.5-1 micrograms/kg/hour | IV | CRI | — | 🌎 NA |
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Sufentanil is an extremely potent, synthetic opioid analgesic (approximately 5 to 10 times more potent than fentanyl and 500 to 1000 times more potent than morphine).
In veterinary medicine, it is primarily utilized as an adjunctive anesthetic or for epidural analgesia.
Key clinical points:
- Potency: Provides profound analgesia and excellent cardiovascular stability compared to many other anesthetics.
- Onset & Recovery: Features a rapid onset of action (1-3 minutes) and a faster recovery time than fentanyl.
- Risks: Carries a significant risk of dose-dependent respiratory and CNS depression, necessitating continuous patient monitoring.
Mechanism of action
Sufentanil acts as a highly selective and potent mu-opioid receptor (MOR) agonist in the central nervous system.
- Binding to the G-protein coupled mu-receptor → inhibits adenylate cyclase → decreases intracellular cAMP.
- This leads to the opening of inward-rectifying potassium channels (causing hyperpolarization) and the closing of voltage-gated calcium channels.
- Result → decreased release of nociceptive neurotransmitters (such as Substance P and glutamate), interrupting pain transmission pathways in the dorsal horn of the spinal cord and altering pain perception in the brain.
Safety & warnings
Contraindications
- Hypersensitivity to sufentanil or other opioids
Adverse effects
- Respiratory depression (dose-related)
- CNS depression
- Bradycardia
- Skeletal muscle rigidity
- Asystole (rare)
- Hypercarbia (rare)
- Hypersensitivity reactions (rare)
Precautions
Warning: Sufentanil is a Class-II controlled substance with extreme potency. It should only be used in situations where patient vital signs can be continuously monitored.
- Geriatric/Debilitated Patients: Use with caution; initial dosage reduction may be required, particularly in those with diminished cardiopulmonary function.
- Organ Impairment: Use with caution in patients with severely diminished renal or hepatic function.
- Pregnancy: Avoid systemic administration to mothers close to giving birth, as offspring may show behavioral alterations (hypotonia, depression).
Drug interactions
May increase bradycardia and hypotension
May increase bradycardia and hypotension
Additive effects can occur, exacerbating CNS or respiratory depression
Can cause cardiovascular depression if used with high dose sufentanil
Monitoring
- Anesthetic and/or analgesic efficacy
- Cardiac rate
- Respiratory rate
- Pulse oximetry or other methods to measure blood oxygenation
Pharmacokinetics
Absorption
Rapid onset of action (1-3 minutes) after intravenous injection. Low oral bioavailability.
Distribution
Highly lipid soluble. Volume of distribution in the central compartment is 0.1 L/kg. Approximately 93% is bound to plasma proteins. Plasma concentrations rapidly decline due to redistribution.
Metabolism
Metabolized primarily in the liver and small intestine via O-demethylation and N-dealkylation.
Elimination
The parent drug and metabolites are excreted primarily in the urine. Plasma clearance is reported to be 11.8 mL/min/kg.
Overdose
In dogs, the LD50 of intravenous sufentanil is 10.1-19.5 mg/kg.
Clinical Signs of Severe Overdose:
- Apnea
- Circulatory collapse
- Pulmonary edema
- Seizures
- Cardiac arrest and death
Treatment: Consists of a combination of supportive therapy (ventilation, cardiovascular support) and administration of an opiate antagonist such as naloxone. Although sufentanil has a fairly rapid half-life, multiple doses of naloxone may be necessary.
Clinical Pearl: Because of the drug's extreme potency, use a tuberculin syringe to measure dosages less than 1 mL, and employ a dosage calculation/measurement double-check system.
Available products
Formulations
- Injection
Human-labeled
- Sufentanil Citrate Injection: 50 micrograms/mL (as base) in 1 mL, 2 mL & 5 mL amps; Sufenta (preservative free)
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Unless otherwise labeled, sufentanil injection should be stored protected from light at room temperature. Sufentanil citrate is hydrolyzed in acidic solutions.
Client information
Sufentanil is a highly potent pain-relieving medication used strictly in a hospital setting by veterinary professionals.
- Why it's used: It is given during surgery or in emergency situations to provide profound pain relief and help with anesthesia.
- Monitoring: Because it is so strong, your pet will be continuously monitored (heart rate, breathing, and oxygen levels) while receiving this medication.
- Safety: It is not prescribed for home use. If your pet received this in the hospital, they may be slightly sleepy or groggy as it wears off.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.