Tribromoethanol-medetomidine combination provides a safe and reversible anesthetic effect in Sprague-Dawley rats

Tribromoethanol typically is used alone as a general anesthetic agent for rodent surgeries. In the present study, the alpha2-adrenergic agonists xylazine and medetomidine were combined with tribromoethanol to examine their use as alternate and safe anesthetic regimes in rats. We also tested the effect of atipamezole, an alpha2-adrenergic antagonist, in reversing the anesthetic effect of the tribromoethanol-medetomidine combination. Male Sprague-Dawley rats were used to evaluate the effects of tribromoethanol (400 mg/kg intraperitoneally [i.p.]) or tribromoethanol (150 mg/kg) and medetomidine (0.5 mg/kg i.p.). Tribromoethanol (400 mg/kg)-treated rats were anesthetized for an average of 10 min, whereas rats that received tribromoethanol (150 mg/kg) and medetomidine (0.5 mg/kg) remained anesthetized for an average of 55 min. Recovery time was approximately 6 min for the tribromoethanol (400 mg/kg) group compared with 21 min for the animals that received tribromoethanol and medetomidine. In a second study, three groups of rats were given tribromoethanol (150 mg/kg) and medetomidine (0.5 mg/kg). Group 1 received atipamezole (an alpha2-antagonist; 2.5 mg/kg i.p.) 10 min after anesthetic induction, and group 2 received the same dosage at 20 min post-induction. Group 3 was allowed to recover without atipamezole treatment. The anesthetic effects in animals from groups 1 and 2 were reversed after administration of atipamezole, whereas group 3 remained anesthetized. This study demonstrates the safe and effective use of tribromoethanol-medetomidine as an anesthetic in the rat.