Cardiovascular stability with Alfaxan Multidose
Alfaxalone, the active ingredient in Alfaxan Multidose, has been demonstrated by many authors, including Muir et al, 2008; Muir et al, 2009; Psatha et al, 2011; Okushima et al, 2014; Pypendop et al, 2019, to provide excellent cardiovascular stability following administration. Unlike other induction agents the baroreceptor reflex, which detects alterations in blood pressure, is not depressed and an increased heart rate is frequently observed following administration of Alfaxan Multidose. This compensatory increase in heart rate permits maintenance of cardiac output and preserves good mucous membrane colour, tissue perfusion and peripheral pulse thus contributing to preservation of patient homeostasis.
In studies performed by Muir et al (2008 and 2009) alfaxalone administered to both dogs and cats at recommended clinical doses had a minimal impact on cardiovascular parameters, when compared to pre-induction baseline data.
Okushima et al, 2014 compared the cardiovascular effects of alfaxalone and propofol in dogs following fentanyl premedication. The conclusion was that alfaxalone is more likely to preserve or increase HR at anaesthetic induction than propofol following opioid premedication i.e. propofol resulted in a greater negative chronotropic effect.
In the 2011 study by Psatha et al the cardiovascular effects of alfaxalone for induction of anaesthesia in dogs considered to be a high anaesthetic risk ASA (American Society of Anaesthesiologists) physical status category III-V were compared to the “gold standard”, cardiovascularly friendly, fentanyl & diazepam induction protocol. Blood pressure remained stable compared to pre-induction values and did not differ between protocols and the compensatory increase in heart rate observed in the alfaxalone group was due to preservation of the baroreceptor reflex as also described by Muir et al (2008).
The 2019 paper by Pypendop et al describes minimal cardiovascular depression following maintenance of anaesthesia with up to 6.5 times the clinical dose of alfaxalone when administered by constant rate infusion in cats.
In conclusion, induction of anaesthesia with Alfaxan Multidose, unlike some other induction agents, supports the preservation of cardiac output and tissue/organ perfusion aiding the maintenance of physiological equilibrium.
- Muir W., Lerche P., Wiese A., Nelson L., Pasloske K. and Whittem T. (2008). Cardiorespiratory and anesthetic effects of clinical and supraclinical doses of alfaxalone in dogs. Vet Anaesth Analg. 35(6): 451-462.
- Muir W., Lerche P., Wiese A., Nelson L., Pasloske K. and Whittem T. (2009). The cardiorespiratory and anesthetic effects of clinical and supraclinical doses of alfaxalone in cats. Vet Anaesth Analg. 36(1): 42-54.
- Okushima S., Vettorato E & Corletto F. (2014). Chronotropic effect of propofol or alfaxalone following fentanyl administration in healthy dogs. Vet Anaesth Analg.
- Psatha, E., Alibhai, H.I.K., Jiminez-Lozano, A., Armitage-Chan, E., Broadbelt, D. (2011). Clinical efficacy and cardiorespiratory effects of alfaxalone, or diazepam/fentanyl for induction of anaesthesia in dogs that are a poor anaesthetic risk. Vet Anaesth Analg. 38, 24-36
- Pypendop B.H., Barter L.S., Pascoe P.J. et al. (2019). Hemodynamic effects of subclinical, clinical and supraclinical plasma alfaxalone concentrations in cats. Vet Anaesth Analg. 46: 597-604