Lack of effect of flumazenil on the reversal of propofol anaesthesia.

Abstract

Propofol, like the benzodiazepines, activates the GABAA receptor-chloride ionophore complex; they potentiate one another. Since neither pharmacodynamic nor pharmacokinetic data concerning drug interaction between flumazenil and propofol is available, and especially considering the relationship of binding sites, flumazenil, the antagonist of benzodiazepines, was investigated to determine its effect upon recovery from propofol anaesthesia. Forty women receiving dilatation and curettage procedures were included in this double-blind test. After 50 micrograms fentanyl, propofol 2 mg.kg-1 was injected for induction and followed by infusion at the rate of 15 mg.kg-1.hr-1. After the operation, patients were given normal saline (Group A) or flumazenil 10 micrograms.kg-1 (Group B) randomly. Recovery time in Group A was 15.2 +/- 5.1 min and Group B 15.8 +/- 4.8 min. Propofol concentrations at the end of infusion were 4.17 +/- 1.33 micrograms.ml-1 (Group A) and 4.03 +/- 1.45 micrograms.ml-1 (Group B); these then declined to 1.22 +/- 0.17 micrograms.ml-1 (Group A) and 1.18 +/- 0.15 micrograms.ml-1 (Group B) when patients were able to open their eyes on command. No significant differences were found between the groups based on propofol concentrations and recovery time, nor did haemodynamic changes differ between them after administration of reversal agents. It was concluded that flumazenil 10 micrograms.kg-1 does not influence recovery from propofol anaesthesia.