Sufentanil and medetomidine anaesthesia in the rat and its reversal with atipamezole and butorphanol

Abstract

SummaryInjectable anaesthetics are widely used to anaesthetize rats, but recovery times are often prolonged. Reversible anaesthetic regimens have the advantage that animals may be recovered quickly, thus reducing the incidence of postoperative complications such as hypothermia, and also providing a means of treating inadvertent anaesthetic overdose. This study assessed and compared the characteristics of anaesthesia induced with combinations of sufentanil and medetomidine administered as a single subcutaneous or intraperitoneal dose, and reversal with butorphanol and atipamezole. Combinations of sufentanil/medetomidine at 40 /lg/150 /lg and 50 /lg/150 /lg/kg administered subcutaneously, and 80 /lg/300/lg/kg by intraperitoneal injection were found to produce surgical anaesthesia for 101± 49, 124± 45 and 76 ± 23 min (means ± SD) respectively. All three combinations produced marked respiratory depression 30min after injection « 50% of resting respiratory rate). Oxygen saturation, measured by pulse oximetry, was < 50% in all groups 30min following drug administration. Subcutaneous administration is recommended since it resulted in a more reliable and more rapid induction of anaesthesia than intraperitoneal administration. The administration of butorphanol and atipamezole (O.2/0.5mg/kg s.c.) resulted in a rapid « 7min) reversal of anaesthesia and an associated respiratory depression. The induction of anaesthesia with sufentanil/medetomidine and its reversal with a combination of atipamezole and butorphanol is an effective technique for anaesthetizing rats. However, due to the marked respiratory depression and the resulting hypoxia, we recommend that this regimen should only be used in animals which are free from respiratory disease and that oxygen should be provided during anaesthesia.

A comparison of medetomidine and its active enantiomer dexmedetomidine when administered with ketamine in mice

“…Although we did not monitor core temperature, the heating pad used throughout the experiment should have helped to prevent hypothermia. In a previous study in rats, the pulse oximeter readings were comparable to arterial blood gas values [40]. Other sources of error could include mechanical artifacts from improper probe placement and electromagnetic interference, but are less likely [39].…”

Anaesthesia with ketamine/medetomidine in the rabbit: influence of route of administration and the effect of combination with butorphanol

“…We therefore consider that, in addition to oxygen supplementation, endotracheal intubation of rabbits should be performed as this allows PPV when respiratory depression is severe. Our previous studies (Hedenqvist et al. 2000a, b; 2001) together with subsequent clinical experience have confirmed that endotracheal intubation can be carried out successfully after induction of anaesthesia with ketamine and medetomidine.…”

“…Butorphanol appears to be rapidly absorbed following SC injection, as judged by its rapid reversal of µ‐agonists such as fentanyl and sufentanil in rats (Hu et al. 1991; Hedenqvist et al. 2000b; 2001), and experience in our laboratory indicates that it has similarly rapid absorption in rabbits, as judged by its effects in reversing the fentanyl component of ‘Hypnorm’ (Janssen Pharmaceuticals).…”

“…An obvious advantage with the technique described is that the effects of medetomidine can be reversed rapidly and completely by administration of atipamezole (Vâhe‐Vahe 1990; Vainio 1990; Hedenqvist et al. 2000b; 2001).…”

Development and validation of a chiral LC‐MS method for the enantiomeric resolution of (+) and (−)‐medetomidine in equine plasma by using polysaccharide‐based chiral stationary phases

“…Calibration curves of each enantiomer were linear over the tested concentration range. Regression equations (the peak area versus the concentration of each enantiomer in ng/mL) showed fairly good linearity with regression coefficients ( r ) of.998 for both levomedetomidine and dexmedetomidine being presented as in Table .…”