title: Evaluation of three midazolam-xylazine mixtures. Preliminary trials in dogs.
abstract: The depressant effects of midazolam and xylazine on the central nervous system (CNS) were evaluated in 12 dogs. Xylazine was administered to six dogs (1.1 mg/kg intravenously [IV]) followed in 5 minutes by midazolam (1.0 mg/kg intramuscularly [IM]). In a second group of six dogs, xylazine (2.2 mg/kg IM) was followed in 5 minutes by midazolam (1.0 mg/kg IV). Both drug regimens induced rapid and profound sedation or anesthesia. Duration of action varied with the doses and routes of administration. Dogs given the high dose of xylazine IM had an arousal time of 95.4 +/- 8.9 minutes and a walking time of 155.4 +/- 8.8 minutes. These values exceeded the IV xylazine values threefold. Partial reversal of CNS depression was accomplished with either a benzodiazepine antagonist (flumazenil) or an alpha-2 antagonist (yohimbine). In a separate trial, a mixture of xylazine (0.55 mg/kg), midazolam (1.0 mg/kg), and butorphanol (0.1 mg/kg) with and without glycopyrrolate was evaluated in eight dogs. As with the xylazine-midazolam combinations, the CNS depressant effect of this mixture was clinically indistinguishable from anesthesia achieved with other rapid-acting injectable agents. Clinical signs of CNS depression were readily and completely antagonized by the simultaneous injection of flumazenil and yohimbine.
authors.affiliation: Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois, Urbana 61801.
authors.forename: W J
authors.initials: WJ
authors.lastname: Tranquilli
authors.forename: M E
authors.initials: ME
authors.lastname: Gross
authors.forename: J C
authors.initials: JC
authors.lastname: Thurmon
authors.forename: G J
authors.initials: GJ
authors.lastname: Benson
mesh_terms: D000758:Anesthesia / Q000662:veterinary*; D000818:Animals; D001143:Arousal / Q000187:drug effects; D001921:Brain / Q000187:drug effects*; D002077:Butorphanol; D004285:Dogs / Q000502:physiology*; D004338:Drug Combinations; D004347:Drug Interactions; D005069:Evaluation Studies as Topic; D005442:Flumazenil / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects; D008874:Midazolam; D012119:Respiration / Q000187:drug effects; D013843:Thiazines; D014991:Xylazine; D015016:Yohimbine / Q000494:pharmacology
chemical_list: D004338:Drug Combinations; D013843:Thiazines; D014991:Xylazine; D015016:Yohimbine; D005442:Flumazenil; D002077:Butorphanol; D008874:Midazolam