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Alfaxalone
Dexmedetomidine + Alfaxalone
1 Dexmedetomidine IM followed by Alfaxalone IV (D-A)
Preoxygenate: Place in an oxygen chamber as sedation commences (Approx 5 mins)
Premedicate: Dexmedetomidine 0.1 mg/kg IM
Induce: One sedation, analgesia and preoxygenation (5 mins) have taken effect to induce with Alfaxalone slow IV to effect (Range 0.3-10 mg/kg)
Intubation: Subsequent intubation and maintenance using a volatile agent (e.g. Isoflurane) with supplementary oxygen is recommended for all painful or significant procedures.
Reversal: Optional. *Reversal with Atipamezole
(Marín et al., 2020)
2 Dexmedetomidine+Buprenorphine IM followed by Alfaxalone IV (D-Bp-A )
Preoxygenate: Place in an oxygen chamber as sedation commences (Approx 5 mins)
Premedicate: Dexmedetomidine 0.1-0.2 mg/kg + Buprenorphine 0.05 mg/kg. Together IM
Induce: One sedation, analgesia, and preoxygenation (5 mins) have taken effect to induce with Alfaxalone at 3-5 mg/kg slow IV to effect (Range 1-10 mg/kg)
Intubation: Subsequent intubation and maintenance using a volatile agent (e.g. Isoflurane) with supplementary oxygen is recommended for all painful or significant procedures.
Reversal: Optional. *Reversal with Atipamezole
(Bradley et al., 2022)
3 Dexmedetomidine and Butorphanol together IM followed by Alfaxalone IV (D-Bt-A)
Preoxygenate: Place in an oxygen chamber as sedation commences (Approx 5 mins)
Premedicate: Dexmedetomidine 0.2 mg/kg + Butorphanol 0.3 mg/kg, together, IM
Induce: One sedation, analgesia and preoxygenation (5 mins) have taken effect to induce with Alfaxalone slow IV to effect (Range 0.3-10 mg/kg)
Intubation: Subsequent intubation and maintenance using a volatile agent (e.g. Isoflurane) with supplementary oxygen alongside appropriate additional analgesia is recommended for all painful or significant procedures.
Reversal: Optional. *Reversal with Atipamezole is covered below
4 Dexmedetomidine, Midazolam, and Alfaxalone together IM (D-M-A)
Preoxygenate: Place in an oxygen chamber as sedation commences (Approx 5 mins)
Sedate: Midazolam 0.2 mg/kg, + Dexmedetomidine 0.1 mg/kg, + Alfaxalone 4 mg/kg, together, IM
Intubation: Subsequent intubation and maintenance using a volatile agent (e.g. Isoflurane) with supplementary oxygen is recommended for all painful or significant procedures.
Reversal: Optional. *Reversal with Atipamezole
(Rousseau-Blass and Pang, 2020)
5 Dexmedetomidine and Midazolam together IM followed by Alfaxalone IV| (D-M-A)
Preoxygenate: Place in an oxygen chamber as sedation commences (Approx 5 mins)
Sedate: Midazolam 0.5 mg/kg + Dexmedetomidine 0.1 mg/kg, together, IM
Induce: One sedation, analgesia and preoxygenation (5 mins) have taken effect to induce with Alfaxalone 0.3 mg/kg, slow IV (to effect), following 5 mins preoxygenation.
Intubation: Subsequent intubation and maintenance using a volatile agent (e.g. Isoflurane) with supplementary oxygen is recommended for all painful or significant procedures.
Reversal: Optional. *Reversal with Atipamezole
(Engbers et al., 2017)
Suitability
Recommendations: Recommendations cover multimodal use alongside Dexmedetomidine in ASA1 and 2 patients.
Suitable patients: The protocols below apply to ASA 1 and 2 patients.
High-risk patients: Clinicians are encouraged to tailor their practices to suit the additional issues encountered in ASA 3 & 4 and address them throughout the peri-anaesthetic period.
Informed Consent: Clinicians must ensure clients understand and accept additional risks.
Patient Preparation
Induction Preparation: Rabbits benefit from premedication, IV access and preoxygenation before Alfaxan induction.
Suitable Handling: Ensure rabbits are kept away from predator contact, smell and excessive noise
Intubation: In clinical settings, animals are usually intubated, or a supraglottic device is placed to allow volatile agents to be employed for anaesthetic maintenance.
Analgesia: Where painful procedures are anticipated, clinicians must employ suitable analgesia agents and monitor the patient for pain.
Reversal | Atipamezole Reversal of Dexmedetomidine
IM Atipamezole at 5 X Dexmedetomidine Dose (This is often the volume of dexmedetomidine administered)
Reversal is carried out alongside ventilatory and thermal support and with the provision of suitable analgesia.
For more detail, see our Atipamezole Monograph.
Use
Multimodal Use: The protocols recommended are multimodal use.
Treatment Goals: Suitable safe sedation or surgical anaesthesia.
Treatment Endpoints: The completion of any sedation or surgical anaesthesia requirement and positive patient outcomes.
Efficacy
Efficacy Profile: Comparative risk of death or other adverse outcomes, such as inadequate depth or duration of surgical anaesthesia or sedation, remain poorly investigated.
Adverse Effects and Contraindications
Adverse Effects Profile: Post-induction apnoea, defined as the cessation of breathing for 30 seconds, is possible if alfaxalone is administered intravenously. This appears more likely with rapid administration or high doses. Anxiolytic premedication and sensitive patient handling will reduce induction tachycardia associated with catecholamine release. Preoxygenation will extend the period where patients showing post-induction issues can be safely supported. Neurological signs (convulsions, myoclonus, tremor, prolonged anaesthesia), cardiorespiratory signs (cardiac arrests, bradycardia, bradypnea) and behavioural signs (hyperactivity, vocalisation) are reported as very rare adverse effects on product datasheets.
Contraindications: Unbstable animals that have not been suitably stabilised in line with their preoperative ASA status.
Reproduction
Safety: According to a product datasheet, studies using alfaxalone in pregnant mice, rats and rabbits have demonstrated no harmful effects on the treated animals' gestation or their offspring's reproductive performance.
Alternative Products and Protocols
Products: A range of options are presented in this formulary. These include multimodal use of medetomidine, dexmedetomidine, propofol and alfaxalone. Additional options, such as buprenorphine and butorphanol, are available in the appropriate opiate monographs.
Protocols: A range of options are presented in this formulary. These include multimodal use of medetomidine, dexmedetomidine, propofol and alfaxalone. Additional options, such as buprenorphine and butorphanol, are available in the appropriate opiate monographs.
Bradley, M.P., Doerning, C.M., Nowland, M.H., Pasloske, K., Lester, P.A., 2022. Evaluation of alfaxalone total intravenous anesthesia in rabbits (Oryctolagus cuniculus) premedicated with dexmedetomidine or dexmedetomidine and buprenorphine. Vet Anaesth Analg S1467-2987(22)00013–7. https://doi.org/10.1016/j.vaa.2022.01.006
Marín, P., Belda, E., Laredo, F.G., Torres, C.A., Hernandis, V., Escudero, E., 2020. Pharmacokinetics and sedative effects of alfaxalone with or without dexmedetomidine in rabbits. Res Vet Sci 129, 6–12. https://doi.org/10.1016/j.rvsc.2019.12.015
Raulic, J., Leung, V.S., Doss, G.A., Graham, J.E., Keller, K.A., Mans, C., Sadar, M.J., Vergneau-Grosset, C., Pang, D.S., 2021. Development and Testing of a Sedation Scale for Use in Rabbits (Oryctolagus cuniculus). J Am Assoc Lab Anim Sci 60, 549–555. https://doi.org/10.30802/AALAS-JAALAS-21-000002
Reabel, S.N., Queiroz-Williams, P., Cremer, J., Hampton, C.E., Liu, C.-C., da Cunha, A., Nevarez, J.G., 2021. Assessment of intramuscular administration of three doses of alfaxalone combined with hydromorphone and dexmedetomidine for endoscopic-guided orotracheal intubation in domestic rabbits (Oryctolagus cuniculus). J Am Vet Med Assoc 259, 1148–1153. https://doi.org/10.2460/javma.20.07.0402
Rousseau-Blass, F., Pang, D.S., 2020. Hypoventilation following oxygen administration associated with alfaxalone-dexmedetomidine-midazolam anesthesia in New Zealand White rabbits. Vet Anaesth Analg 47, 637–646. https://doi.org/10.1016/j.vaa.2020.04.012
Expert Opinion
1317822 Extrapolation of pharmacological properties in man and veterinary species. Some material employed in collating the data displayed here was taken from veterinary product datasheets or extrapolated from pharmacology texts.