stability1 and that ketamine may antagonize hypoventilation caused by alfentanil.2. Although a ketamine±alfentanil combination may provide an excellent basis ...
British Journal of Anaesthesia 88 (1): 94±100 (2002)
Concurrent ketamine and alfentanil administration: pharmacokinetic considerations S. R. Edwards, C. F. Minto and L. E. Mather* Centre for Anaesthesia and Pain Management Research, University of Sydney at Royal North Shore Hospital, St Leonards, NSW 2065, Australia *Corresponding author Background. A ketamine±alfentanil combination has been suggested for total i.v. anaesthesia. We determined the pharmacokinetics of ketamine and alfentanil, alone and together, in three groups of adult male rats, to assess any pharmacokinetic interaction. Methods. Group 1 animals were infused with i.v. ketamine for 5 min; in group 2, constant low plasma concentrations of alfentanil were maintained by computer-controlled infusion; in group 3, the treatments were combined. Serial plasma and terminal tissue concentrations were measured by high performance liquid chromatography or gas chromatography-mass spectrometry. Results. In the presence of alfentanil, the mean plasma ketamine concentration±time area under the curve (AUC) value was signi®cantly lower (by 13%, P forebrain: P=0.02). In group 1, norketamine enantiomer concentrations in the CNS and myocardium were lower than the limit of (spectrophotometric) quantitation following HPLC-chiral separation. Ketamine CNS tissue concentrations were signi®cantly higher in forebrain (P
