Effect of xylazine and ketamine on the pharmacokinetics of alfentanil during halothane anaesthesia

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We measured plasma concentrations of alfentanil in two horses after three different randomly ordered treatments. Each horse received halothane in oxygen by mask followed by a bolus dose of alfentanil 60 μg kg-1 i. v., halothane in oxygen by mask followed by an i.v. alfentanil infusion for 120 min and xylazine and ketamine followed by halothane and a bolus dose of alfentanil 60 μg kg-1 i.v. Halothane was maintained at 1.05-1.07% end-tidal concentration with a Paco2 of 6-7.3 kPa. The plasma concentration-time curves were similar after bolus and infusion doses of alfentanil with halothane and could be fitted to a two-compartment open model. A plateau was noted in the plasma concentration-time curve in the presence of xylazine-ketamine which could not be modelled adequately, but suggested a three-compartment open model with an additional input component. (Br. J. Anaesth. 1994; 72: 345-347)

Original languageEnglish (US)
Pages (from-to)345-347
Number of pages3
JournalBritish Journal of Anaesthesia
Issue number3
StatePublished - Mar 1994



  • Pharmacokinetics alfentanil

ASJC Scopus subject areas

  • Statistics, Probability and Uncertainty
  • Applied Mathematics
  • Mathematics(all)
  • Statistics and Probability
  • Agricultural and Biological Sciences (miscellaneous)
  • Anesthesiology and Pain Medicine

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