Effect of meloxicam and butorphanol on minimum alveolar concentration of isoflurane in rabbits

Am J Vet Res. 2006 May;67(5):770-4. doi: 10.2460/ajvr.67.5.770.


Objective: To determine the effects of meloxicam and butorphanol on minimum alveolar concentration of isoflurane (MAC(ISO)) in rabbits.

Animals: 10 healthy young adult female rabbits.

Procedure: Rabbits were anesthetized with isoflurane on 3 occasions in a blinded, randomized complete block design to determine the MAC(ISO) associated with administration of meloxicam (0, 0.3, or 1.5 mg/kg, PO) and butorphanol (0.4 mg/kg, IV). The MAC(ISO) was determined by use of a paw clamp technique as the end-tidal concentration of isoflurane halfway between the values that allowed or inhibited purposeful movement. Rectal temperature, end-tidal CO2 concentration, heart rate, oxygen saturation, and arterial blood pressure were measured to evaluate cardiopulmonary function.

Results: Mean +/- SE MAC(ISO) in saline (0.9% NaCl) solution-treated rabbits was 2.49 +/- 0.07% and was not significantly different from that associated with administration of meloxicam at 0.3 mg/kg (2.56 +/- 0.07%) or 1.5 mg/kg (2.66 +/- 0.07%). Butorphanol significantly reduced the MAC(ISO) to 2.30 +/- 0.07% when administered with saline solution alone, 2.27 +/- 0.07% when administered with 0.3 mg of meloxicam/kg, and 2.33 +/- 0.07% when administered with 1.5 mg of meloxicam/kg. The percentage reduction in MAC(ISO) was significantly greater for rabbits that received butorphanol and meloxicam at either dose, compared with butorphanol and saline solution.

Conclusions and clinical relevance: Results indicated that meloxicam does not have a direct isoflurane-sparing effect and does not interfere with the anesthetic-sparing effect of butorphanol in rabbits.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Analgesics, Non-Narcotic / pharmacology*
  • Analgesics, Opioid / pharmacology*
  • Anesthetics, Inhalation / pharmacokinetics*
  • Animals
  • Blood Pressure / drug effects
  • Butorphanol / pharmacology*
  • Cross-Over Studies
  • Dose-Response Relationship, Drug
  • Double-Blind Method
  • Drug Interactions
  • Female
  • Heart Rate / drug effects
  • Isoflurane / pharmacokinetics*
  • Meloxicam
  • Rabbits
  • Thiazines / pharmacology*
  • Thiazoles / pharmacology*


  • Analgesics, Non-Narcotic
  • Analgesics, Opioid
  • Anesthetics, Inhalation
  • Thiazines
  • Thiazoles
  • Isoflurane
  • Butorphanol
  • Meloxicam