Open AccessPhysostigmine and Anesthetic Requirement for Halothane in Dogs
Author(s) -
Richard W. Horrigan
Publication year - 1978
Publication title -
anesthesia and analgesia/anesthesia and analgesia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.404
H-Index - 201
eISSN - 1526-7598
pISSN - 0003-2999
DOI - 10.1213/00000539-197803000-00006
Subject(s) - medicine , halothane , physostigmine , anesthetic , anesthesia , pharmacology , acetylcholine
To investigate the effect of physostigmine on central nervous system (CNS) depression produced by halothane, control halothan minimum alveolar concentration (MAC) measured over 1 hour in 7 dogs was compared to MAC 30 minutes after each sequential IV dose of 0.04, 0.4, and 4 mg/kg physostigmine. MAC decreased 6.8, 11.1 (p less than 0.05), and 35.9 (p less than 0.01) percent, respectively. Six dogs were observed for an acute increase in halothane requirement in the first 30 minutes after administration of physostigmine. All 6 showed such a response at 1 or more dose levels, beginning within 1 to 5 minutes after administration and lasting 2 to 30 minutes (p less than 0.05). Five other dogs were tested with neostigmine in the same doses and showed respective decreases in MAC of 7.9, 16.6 (p less than 0.01), and 17.5 ( less than 0.01) percent. No dog showed an acute increase in anesthetic requirement. Intravenous atropine 0.5 mg/kg failed to further alter MAC after 4 mg/kg neostigmine. Physostigmine transiently antagonizes halothane anesthesia, presumably by facilitating cholinergic transmission in the CNS; neostigmine does not. After this initial response, both drugs decrease anesthetic requirement. If these data may be extrapolated to patients, they suggest that physostigmine is not an effective antagonist to postoperative somnolence due to halothane.