Effects of methoxyflurane anesthesia on the pharmacokinetics of I-125-IAZAin Sprague-Dawley rats

Effects of methoxyflurane anesthesia on the pharmacokinetics of intravenous I-125-IAZA in rats are reported. No significant differences in t(1/2 alpha ), t(1/2 beta), V-ss, and Cl-TB for total radioactivity (I-125-IAZA and met abolites) were observed between the anesthetized (Group 1, n = 4) and nonan esthetized (Group 2, n = 3) animals. For I-125-IAZA, Cl-TB increased from 6 46 +/- 52 ml/h/kg to 2250 +/- 351 ml/h/kg and t(1/2 beta) decreased from 97 .7 +/- 17.5 min to 35.6 +/- 5.4 min, for Groups 1 and 2, respectively. Ther e were no differences in V-ss or t(1/2 alpha) between the two groups. These findings support literature reports of anesthetic effects on xenobiotic ph armacokinetics, and indicate a need for caution in the evaluation of precli nical imaging studies in which animals are immobilized with anesthetics. (C ) 2000 Elsevier Science Inc. All rights reserved.