Anesthetic properties of propofol in African clawed frogs (Xenopus laevis).

The objective of this study was to determine the level of anesthesia attained in Xenopus laevis frogs using a propofol bath administration. Thirty-three nonbreeding female Xenopus laevis frogs were used. At 175 mg/l, all frogs died after bath administration. An appropriate anesthetic dose was determined to be 88 mg/l for 15 min. After administration of this dose, the acetic acid test, withdrawal reflex, righting reflex, heart rate, and respiratory frequency were used to evaluate central nervous system depression. Pharmacokinetics of propofol were calculated after blood concentration determination by tandem liquid chromatography-mass spectrometry analyses. Short-duration anesthesia (less than 30 min) was obtained, and in many frogs, muscular fasciculation was seen during the acetic acid test. The area under the time-concentration curve (AUC0-t) was 24.07 microg.min/ml, and AUCinf was 24.71 microg.min/ml. The elimination half-life was 1.18 h. When administered as a single-bath immersion for 15 min, propofol does not appear to be a safe and effective anesthetic for Xenopus laevis frogs, due to a narrow dose-effect window, short duration, and shallow level of anesthesia obtained.