Failure of intravenous flumazenil to antagonize alfaxalone anesthesia in cats

ObjectivesThe aim of the present study was to assess the gamma-aminobutyric acid type A (GABA_A) receptor antagonist flumazenil and its effect on the anesthetic activity of the GABA_A receptor agonist alfaxalone when administered intravenously in cats.MethodsA prospective, randomized, blinded, two-period two-treatment crossover study was conducted. Eight (six male, two female) healthy adult neutered cats, 4.5-7.0 kg body weight, owned by IndyVet Emergency and Specialty Hospital were enrolled. Cats were randomly assigned to one of two treatment groups, flumazenil or saline (period 1). During period 2, cats were administered the opposite treatment. Treatment was either 0.1 mg/kg flumazenil or an equal volume of 0.9% sodium chloride. Before treatment, a published, abbreviated alfaxalone protocol was administered, consisting of an intravenous (IV) dose of 2 mg/kg over 1 min, followed by an abbreviated two-step IV alfaxalone infusion of 0.4 mg/kg/min for 10 mins, then 0.3 mg/kg/min for 30 mins. Physiologic parameters, time to lateral recumbency, sternal recumbency and standing, duration of anesthesia, quality of induction and maintenance of anesthesia, and quality of recovery were assessed.ResultsThe treatment by time interaction was not significant for any variable. Pulse rate was significantly higher in the flumazenil group than the saline group (mean 176.01 vs 169.57; <i>P</i> = 0.0067).Conclusions and relevanceFlumazenil administered at 0.1 mg/kg intravenously over 1 min did not antagonize the effects of alfaxalone in cats. Further investigations are required to investigate an appropriate dose or other drug to antagonize alfaxalone and its judicious use in clinical settings.