Alfaxalone
3-alpha-hydroxy-5-alpha-pregnane-11,20-dione
Also known as: Alfaxan-CD RTU · Alfaxan Multidose · alfaksaloni · alfaxalona · alfaxalonum · alphaxalone · GR-2/234
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Audited v13 dosing evidence
Reviewed non-calculator evidenceReviewed non-calculator evidence (10)
Evidence only — not for automatic calculation
Crocodilians/induction, but unpredictable results
TABLE 127.5. Agent: Alfaxalone(Alfaxan, Jurox). Dosage: 3 mg/kg IV252. Species/Comments: Crocodilians/induction, but unpredictable results.
Evidence only — not for automatic calculation
Lizards, chelonians/induction, 35–40 min; duration, 15–35 min; good muscle relaxation; variable results
TABLE 127.5. Agent: Alfaxalone(Alfaxan, Jurox). Dosage: 15 mg/kg IM229. Species/Comments: Lizards, chelonians/induction, 35–40 min; duration, 15–35 min; good muscle relaxation; variable results.
Evidence only — not for automatic calculation
Most species/good muscle relaxation; variable results; drug requires more evaluation; may have violent recovery;198don’t use within 10 days of DMSO treatment
TABLE 127.5. Agent: Alfaxalone(Alfaxan, Jurox). Dosage: 6–9 mg/kg IV, or 9–15 mg/kg IM182. Species/Comments: Most species/good muscle relaxation; variable results; drug requires more evaluation; may have violent recovery;198don’t use within 10 days of DMSO treatment.
Evidence only — not for automatic calculation
Horsfield’s tortoises (males only)/light to moderate sedation with no to minimal analgesia; red-eared slider turtles/light sedation of short duration; PD turtles administered 10 mg/kg at low temperature more relaxed than warm, and turtles administered 20 mg/kg at warm temperature were most relaxed
TABLE 127.5. Agent: Alfaxalone(Alfaxan, Jurox). Dosage: 10–20 mg/kg IM113,164,300. Species/Comments: Horsfield’s tortoises (males only)/light to moderate sedation with no to minimal analgesia; red-eared slider turtles/light sedation of short duration; PD turtles administered 10 mg/kg at low temperature more relaxed than warm, and turtles administered 20 mg/kg at warm temperature were most relaxed.
Evidence only — not for automatic calculation
Turtles, tortoises/induction
TABLE 127.5. Agent: Alfaxalone(Alfaxan, Jurox). Dosage: 5 mg/kg IV170. Species/Comments: Turtles, tortoises/induction.
Evidence only — not for automatic calculation
Most species
TABLE 127.5. Agent: Alfaxalone(Alfaxan, Jurox). Dosage: 6–15 mg/kg IM, IV298. Species/Comments: Most species.
Evidence only — not for automatic calculation
Snakes, lizards/induction; not effective for blotched blue-tongued skinks
TABLE 127.5. Agent: Alfaxalone(Alfaxan, Jurox). Dosage: 9 mg/kg IV290. Species/Comments: Snakes, lizards/induction; not effective for blotched blue-tongued skinks.
Evidence only — not for automatic calculation
Red-eared slider turtles, Eastern painted turtles, yellow-spotted Amazon river turtles, other undocumented turtle species/anesthetic induction
TABLE 127.5. Agent: Alfaxalone(Alfaxan, Jurox). Dosage: 20 mg/kg IM141. Species/Comments: Red-eared slider turtles, Eastern painted turtles, yellow-spotted Amazon river turtles, other undocumented turtle species/anesthetic induction.
Evidence only — not for automatic calculation
Chelonians (red-eared sliders)/surgical anesthesia with good relaxation
TABLE 127.5. Agent: Alfaxalone(Alfaxan, Jurox). Dosage: 24 mg/kg ICe111. Species/Comments: Chelonians (red-eared sliders)/surgical anesthesia with good relaxation.
Evidence only — not for automatic calculation
Bearded dragons/effective for induction of anesthesia; respiratory depression noted
TABLE 127.5. Agent: Alfaxalone(Alfaxan, Jurox). Dosage: 12 mg/kg IV262. Species/Comments: Bearded dragons/effective for induction of anesthesia; respiratory depression noted.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Alfaxalone is a neuroactive steroid molecule that functions as a rapid-acting central nervous system depressant and general anesthetic. It is primarily used for the induction and maintenance of anesthesia in veterinary patients.
Clinical Pearls & Pharmacological Profile:
- Formulation Evolution: The modern formulation (Alfaxan®) uses 2-hydroxypropyl-beta-cyclodextrin (HPCD) as a solubilizing agent. This is a significant improvement over the historical product (Saffan®), which contained polyethoxylated castor oil (Cremophor EL) and caused severe histamine release and anaphylaxis, particularly in cats.
- Cardiorespiratory Effects: While generally considered to have a wide safety margin, alfaxalone can cause dose-dependent respiratory depression and post-induction apnea, especially if administered rapidly IV. Cardiovascular parameters are typically well-maintained, though compensatory tachycardia may occur.
- Analgesia: Alfaxalone provides negligible analgesic effects. It must be combined with appropriate pure analgesics (e.g., opioids) for painful procedures.
- Recovery: Recovery is generally rapid and smooth due to its short half-life and lack of accumulation, but patients can experience psychomotor excitement (paddling, vocalization, twitching) if stimulated or if inadequate premedication/analgesia was provided.
Mechanism of action
Alfaxalone exerts its anesthetic effects by interacting with GABA_A (gamma-aminobutyric acid type A) receptors in the central nervous system.
- Mechanism: It binds to specific transmembrane domains on the GABA_A receptor complex.
- Pathway: Binding → Enhances the binding of the inhibitory neurotransmitter GABA to the receptor → Increases the frequency and duration of chloride (Cl⁻) ion channel opening → Influx of chloride ions into the neuron → Hyperpolarization of the postsynaptic cell membrane → Inhibition of neural action potential transmission → Dose-dependent CNS depression (ranging from sedation to general anesthesia).
Safety & warnings
Contraindications
- Concurrent use with other injectable general anesthetic agents (e.g., propofol, thiopental)
- Situations where endotracheal intubation, positive pressure ventilation, and oxygen support are unavailable
- Animals less than 12 weeks of age (safety not established)
Adverse effects
- Respiratory depression
- Post-induction apnea
- Hypotension (dose-dependent)
- Cardiac arrhythmias (primarily secondary to hypoxemia/hypercapnia)
- Psychomotor excitement during recovery (especially if unstimulated or lacking premedication)
Precautions
Critical Warning: Post-induction apnea is common (up to 44% in dogs, 19% in cats). Alfaxalone should only be used when endotracheal intubation and oxygen supplementation/ventilation are immediately available.
- Administration Rate: Give slowly IV (over 60 seconds or titrated to effect) to minimize the risk of severe apnea.
- Hepatic Dysfunction: Use with caution; lower dosages or increased dosing intervals may be required as the drug undergoes extensive hepatic metabolism.
- Recovery Environment: Keep patients in a quiet, unstimulating environment during recovery to minimize psychomotor excitement. Avoid handling unless necessary.
- Analgesia: Always provide concurrent appropriate pain control, as alfaxalone offers no analgesia.
Drug interactions
Potentiates the CNS and respiratory depressant effects. Significantly reduces the required induction and maintenance doses of alfaxalone.
Should not be used concurrently according to the manufacturer label.
Should not be used concurrently according to the manufacturer label.
Increased risk of severe CNS and respiratory depression
Synergistic CNS depression; significantly reduces the required induction dose of alfaxalone
Synergistic CNS depression; reduces the required induction dose of alfaxalone.
Profound synergy; significantly reduces alfaxalone dose requirements and may exacerbate cardiovascular and respiratory depression.
Enhanced sedation and increased risk of hypotension.
Synergistic CNS depression; significantly reduces the required induction dose of alfaxalone.
Synergistic CNS depression; reduces alfaxalone dose requirements.
Monitoring
- Level of anesthesia / CNS depression (jaw tone, palpebral reflex)
- Respiratory rate, rhythm, and depth (capnography and pulse oximetry highly recommended due to apnea risk)
- Cardiovascular status (heart rate, ECG rhythm, blood pressure)
- Body temperature (monitor for hypothermia during anesthesia)
Pharmacokinetics
Half-life
Absorption
Rapid onset following intravenous administration. Well absorbed following deep intramuscular injection in cats.
Distribution
Widely distributed. Volume of distribution (Vd) in dogs is approximately 2.5 L/kg; in cats, approximately 2 L/kg.
Metabolism
Undergoes extensive hepatic metabolism via Phase I (cytochrome P450 dependent) and Phase II (conjugation dependent) pathways. Cats form alfaxalone sulfate and alfaxalone glucuronide; dogs form only alfaxalone glucuronide.
Elimination
Metabolites are eliminated via hepatic/fecal and renal routes. Clearance in dogs is ~54 mL/kg/min. Clearance in cats is dose-dependent (25.1 mL/kg/min at 5 mg/kg; 14.8 mL/kg/min at 25 mg/kg). No clinically relevant accumulation occurs with multiple doses.
Overdose
Overdoses up to 25 mg/kg primarily result in severe cardiorespiratory depression.
Clinical Signs of Toxicity:
- Severe hypoventilation and prolonged apnea
- Hypotension
- Cardiac arrhythmias
Treatment:
- Immediate endotracheal intubation and positive pressure ventilation with 100% oxygen.
- Cardiovascular support (IV fluids, vasopressors/inotropes if hypotension is severe).
- Continuous monitoring until the drug is metabolized and cleared.
Available products
Formulations
- 10 mg/mL injection (10 mL and 20 mL vials)
Veterinary
- Alfaxan® 10 mg/mL injection (10 mL and 20 mL vials)
Regulatory status
Approved for induction and maintenance of anesthesia.
Prescription Only Medicine - Veterinarian.
No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store at room temperature (<30°C) and protect from light. Do not freeze. According to the New Zealand label, broached (punctured) vials should preferably be used within 24 hours, but may be stored at 4°C for up to 7 days provided contamination is avoided. Discard if the solution is not clear, colorless, or contains particulate matter.
Client information
What is Alfaxalone? Alfaxalone is a fast-acting, highly safe injectable anesthetic used to induce sleep before surgery or to provide heavy sedation for minor procedures.
What to Expect:
- Rapid Action: Your pet will fall asleep very quickly and smoothly after the injection.
- Monitoring: Because it can temporarily slow breathing, your veterinary team will closely monitor your pet's breathing, heart rate, and oxygen levels throughout the procedure.
- Recovery: Pets usually wake up quickly once the procedure is over. However, during the recovery phase, they can be sensitive to noise, light, and touch. They may twitch, paddle their legs, or vocalize if startled.
- Post-Care: The veterinary staff will keep your pet in a quiet, warm, and dark environment until they are fully awake and steady on their feet. No special at-home care is required specifically for this drug once your pet is discharged.
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.