Sufentanil
**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: 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.
Dosing by species
- 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
- As a pre-med · 3 micrograms/kg IV · IV · Single dose · As a combination for induction: Sufentanil 3 micrograms/kg IV first, then diazepam or midazolam 0.2-0.5 mg IV.
- 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 · Onset of action in 10-15 minutes.
- Acute pain relief in an emergency · 0.75-2 micrograms/kg IV ; constant rate infusion of 1-2 micrograms/kg/hour · IV · CRI
- 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 · Duration of effect: 2-6 hours.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Routes of administration
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)
Drug interactions
- Beta-adrenergic blockers · May increase bradycardia and hypotension
- Calcium-channel blockers · May increase bradycardia and hypotension
- CNS depressants (e.g., barbiturates) · Additive effects can occur, exacerbating CNS or respiratory depression
- Nitrous oxide · 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
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.
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.