title: Evaluation of the arrhythmogenicity of a low dose of acepromazine: comparison with xylazine.
abstract: Alteration in the arrhythmogenic dose of epinephrine (ADE) was determined in 6 healthy dogs under halothane anesthesia following the administration of xylazine at 1.1 mg/kg i.v. and acepromazine at 0.025 mg/kg i.v. The order of treatment was randomly assigned with each dog receiving both treatments and testing was carried out on 2 separate occasions with at least a 1 wk interval. The ADE determinations were made prior to drug administration during halothane anesthesia (CNTL) and then 20 min and 4 h following drug treatment. Epinephrine was infused for 3 min at increasing dose rates (2.5, 5.0, 10.0 micrograms/kg/min) until the arrhythmia criterion (4 or more intermittent or continuous premature ventricular contractions) was reached within the 3 min of infusion or the 1 min following cessation. The interinfusion interval was 20 min. There was a significant difference (P = 0.0001) in the ADE determined following acepromazine administration at 20 min (20.95 micrograms/kg +/- 2.28 SEM) compared to CNTL (6.64 micrograms/kg +/- 1.09), xylazine at 20 min (5.82 micrograms/kg +/- 0.95) and 4 h (6.13 micrograms/kg +/- 1.05), and acepromazine at 4 h (7.32 micrograms/kg +/- 0.34). No other significant differences existed (P < 0.05). In this study we were unable to show any sensitization to epinephrine following xylazine administration during halothane anesthesia, while a protective effect was shown with a low dose of acepromazine.
authors.affiliation: Department of Clinical Studies, Ontario Veterinary College, University of Guelph.
authors.forename: D
authors.initials: D
authors.lastname: Dyson
authors.forename: G
authors.initials: G
authors.lastname: Pettifer
mesh_terms: D000075:Acepromazine / Q000008:administration & dosage / Q000494:pharmacology*; D000322:Adrenergic Agonists / Q000008:administration & dosage / Q000494:pharmacology; D000777:Anesthetics / Q000008:administration & dosage / Q000494:pharmacology*; D018685:Anesthetics, Inhalation / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000008:administration & dosage / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D004285:Dogs / Q000502:physiology*; D018492:Dopamine Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004837:Epinephrine / Q000008:administration & dosage / Q000494:pharmacology; D005260:Female; D006221:Halothane / Q000008:administration & dosage / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects* / Q000502:physiology; D007262:Infusions, Intravenous / Q000379:methods / Q000662:veterinary; D008297:Male; D013997:Time Factors; D014991:Xylazine / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D000322:Adrenergic Agonists; D000777:Anesthetics; D018685:Anesthetics, Inhalation; D000889:Anti-Arrhythmia Agents; D018492:Dopamine Antagonists; D014991:Xylazine; D000075:Acepromazine; D006221:Halothane; D004837:Epinephrine