Failure of yohimbine to reverse ketamine anesthesia in rhesus monkeys.

Yohimbine hydrochloride has been used experimentally to reverse the anesthetic effects of ketamine and xylazine in dogs, cats, cattle and mule deer, but there are no reports of its use in nonhuman primates. Nine adult female rhesus monkeys were given an intravenous dose of either 0.5 mg/kg yohimbine hydrochloride or saline 10 minutes after intramuscular administration of 10 mg/kg ketamine hydrochloride. There was no difference in the duration of anesthesia between the yohimbine and saline treatments, suggesting yohimbine is not effective in the rhesus monkey.