Pharmacokinetics of dexmedetomidine in isoflurane-anesthetized New Zealand White rabbits.

Objective: To characterize the pharmacokinetics of dexmedetomidine when administered as a short intravenous (IV) infusion to isoflurane-anesthetized rabbits.

Study Design: Experimental study.

Animals: A total of six healthy adult female New Zealand White rabbits.

Methods: Rabbits were anesthetized with isoflurane in oxygen. Following determination of isoflurane minimum alveolar concentration (MAC), the anesthetic dose was reduced to 0.7 × MAC, and dexmedetomidine hydrochloride (20 μg kg) was infused IV over 5 minutes. Arterial blood samples were obtained immediately before and at 1, 2, 5, 6, 7, 10, 15, 30, 60, 90, 120, 240 and 360 minutes following termination of the infusion. Samples were transferred into tubes containing ethylenediaminetetraacetic acid and centrifuged immediately. The plasma was harvested and stored at -80 °C until analyzed. Concentrations of dexmedetomidine in plasma were determined by liquid chromatography mass spectrometry. Compartment models were fitted to the time and concentration data using nonlinear regression.

Results: A three-compartment model best fit the data set. Median volume of distribution at steady state and terminal half-life were 3169 mL kg (range, 2182-3859 mL kg) and 80 minutes (range, 72-88 minutes), respectively.

Conclusions And Clinical Relevance: The pharmacokinetics of dexmedetomidine in isoflurane-anesthetized, healthy, New Zealand White rabbits were characterized in this study. Data from this study can be used to determine dosing regimens for dexmedetomidine in isoflurane-anesthetized rabbits.