Alfaxalona
Alfaxalone
3-alpha-hydroxy-5-alpha-pregnane-11,20-dione
También conocido como: Alfaxan-CD RTU · Alfaxan Multidose · alfaksaloni · alfaxalona · alfaxalonum · alphaxalone · GR-2/234
Revisado por el equipo veterinario de VetSheetActualizado 5 abr 2026Referencia veterinaria basada en la evidencia
Evidencia de dosis v13 auditada
Evidencia revisada no calculableEvidencia revisada no calculable (10)
Solo evidencia; no apta para cálculo automático
Crocodilians/induction, but unpredictable results
TABLE 127.5. Agent: Alfaxalone(Alfaxan, Jurox). Dosage: 3 mg/kg IV252. Species/Comments: Crocodilians/induction, but unpredictable results.
Solo evidencia; no apta para cálculo automático
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.
Solo evidencia; no apta para cálculo automático
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.
Solo evidencia; no apta para cálculo automático
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.
Solo evidencia; no apta para cálculo automático
Turtles, tortoises/induction
TABLE 127.5. Agent: Alfaxalone(Alfaxan, Jurox). Dosage: 5 mg/kg IV170. Species/Comments: Turtles, tortoises/induction.
Solo evidencia; no apta para cálculo automático
Most species
TABLE 127.5. Agent: Alfaxalone(Alfaxan, Jurox). Dosage: 6–15 mg/kg IM, IV298. Species/Comments: Most species.
Solo evidencia; no apta para cálculo automático
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.
Solo evidencia; no apta para cálculo automático
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.
Solo evidencia; no apta para cálculo automático
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.
Solo evidencia; no apta para cálculo automático
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.
Las dosis son una referencia clínica para profesionales veterinarios autorizados. Confirme siempre con el prospecto actual y cada paciente individual.
Resumen
La alfaxalona es una molécula esteroide neuroactiva que funciona como un depresor del sistema nervioso central de acción rápida y anestésico general. Se utiliza principalmente para la inducción y el mantenimiento de la anestesia en pacientes veterinarios.
Perlas clínicas y perfil farmacológico:
- Evolución de la formulación: La formulación moderna (Alfaxan®) utiliza 2-hidroxipropil-beta-ciclodextrina (HPCD) como agente solubilizante. Esta es una mejora significativa respecto al producto histórico (Saffan®), que contenía aceite de ricino polietoxilado (Cremophor EL) y causaba una liberación severa de histamina y anafilaxia, particularmente en gatos.
- Efectos cardiorrespiratorios: Aunque generalmente se considera que tiene un amplio margen de seguridad, la alfaxalona puede causar depresión respiratoria dependiente de la dosis y apnea post-inducción, especialmente si se administra rápidamente por vía IV. Los parámetros cardiovasculares suelen mantenerse bien, aunque puede ocurrir taquicardia compensatoria.
- Analgesia: La alfaxalona proporciona efectos analgésicos insignificantes. Debe combinarse con analgésicos puros apropiados (p. ej., opioides) para procedimientos dolorosos.
- Recuperación: La recuperación es generalmente rápida y suave debido a su vida media corta y falta de acumulación, pero los pacientes pueden experimentar excitación psicomotora (pedaleo, vocalización, espasmos) si son estimulados o si se proporcionó una premedicación/analgesia inadecuada.
Mecanismo de acción
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).
Seguridad y advertencias
Contraindicaciones
- 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)
Efectos adversos
- 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)
Precauciones
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.
Interacciones farmacológicas
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.
Monitorización
- 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)
Farmacocinética
Vida media
Absorción
Rapid onset following intravenous administration. Well absorbed following deep intramuscular injection in cats.
Distribución
Widely distributed. Volume of distribution (Vd) in dogs is approximately 2.5 L/kg; in cats, approximately 2 L/kg.
Metabolismo
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.
Eliminación
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.
Sobredosis
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.
Productos disponibles
Formulaciones
- 10 mg/mL injection (10 mL and 20 mL vials)
Veterinario
- Alfaxan® 10 mg/mL injection (10 mL and 20 mL vials)
Estado regulador
Approved for induction and maintenance of anesthesia.
Prescription Only Medicine - Veterinarian.
Sin datos reguladores para: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Almacenamiento y estabilidad
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.
Información para el cliente
¿Qué es la alfaxalona? La alfaxalona es un anestésico inyectable de acción rápida y alta seguridad que se utiliza para inducir el sueño antes de una cirugía o para proporcionar una sedación profunda para procedimientos menores.
Qué esperar:
- Acción rápida: Su mascota se quedará dormida muy rápida y suavemente después de la inyección.
- Monitoreo: Debido a que puede ralentizar temporalmente la respiración, su equipo veterinario monitoreará de cerca la respiración, la frecuencia cardíaca y los niveles de oxígeno de su mascota durante todo el procedimiento.
- Recuperación: Las mascotas suelen despertar rápidamente una vez finalizado el procedimiento. Sin embargo, durante la fase de recuperación, pueden ser sensibles al ruido, la luz y el tacto. Pueden tener espasmos, pedalear con las patas o vocalizar si se asustan.
- Cuidados posteriores: El personal veterinario mantendrá a su mascota en un ambiente tranquilo, cálido y oscuro hasta que esté completamente despierta y estable. No se requiere ningún cuidado especial en casa específicamente para este medicamento una vez que su mascota sea dada de alta.
La referencia de medicamentos de VetSheet está destinada a profesionales veterinarios autorizados como ayuda para la toma de decisiones clínicas, no como sustituto del criterio profesional ni del prospecto actual del fabricante.