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Pharmacokinetics of inhaled anesthetics in green iguanas (Iguana iguana)

Robert J. Brosnan DVM, PhD1, Bruno H. Pypendop Dr Med Vet, Dr Vet Sci2, Linda S. Barter MVSc3, and Michelle G. Hawkins VMD4
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  • 1 Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA 95616.
  • | 2 Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA 95616.
  • | 3 Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA 95616.
  • | 4 Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616.

Abstract

Objective—To test the hypothesis that differences in anesthetic uptake and elimination in iguanas would counter the pharmacokinetic effects of blood:gas solubility and thus serve to minimize kinetic differences among inhaled agents.

Animals—6 green iguanas (Iguana iguana).

Procedures—Iguanas were anesthetized with isoflurane, sevoflurane, or desflurane in a Latin-square design. Intervals from initial administration of an anesthetic agent to specific induction events and from cessation of administration of an anesthetic agent to specific recovery events were recorded. End-expired gas concentrations were measured during anesthetic washout.

Results—Significant differences were not detected for any induction or recovery events for any inhalation agent in iguanas. Washout curves best fit a 2-compartment model, but slopes for both compartments did not differ significantly among the 3 anesthetics.

Conclusions and Clinical Relevance—Differences in blood:gas solubility for isoflurane, sevoflurane, and desflurane did not significantly influence differences in pharmacokinetics for the inhalation agents in iguanas.

Abstract

Objective—To test the hypothesis that differences in anesthetic uptake and elimination in iguanas would counter the pharmacokinetic effects of blood:gas solubility and thus serve to minimize kinetic differences among inhaled agents.

Animals—6 green iguanas (Iguana iguana).

Procedures—Iguanas were anesthetized with isoflurane, sevoflurane, or desflurane in a Latin-square design. Intervals from initial administration of an anesthetic agent to specific induction events and from cessation of administration of an anesthetic agent to specific recovery events were recorded. End-expired gas concentrations were measured during anesthetic washout.

Results—Significant differences were not detected for any induction or recovery events for any inhalation agent in iguanas. Washout curves best fit a 2-compartment model, but slopes for both compartments did not differ significantly among the 3 anesthetics.

Conclusions and Clinical Relevance—Differences in blood:gas solubility for isoflurane, sevoflurane, and desflurane did not significantly influence differences in pharmacokinetics for the inhalation agents in iguanas.

Contributor Notes

Supported by the Center for Companion Animal Health, School of Veterinary Medicine, University of California–Davis.

Address correspondence to Dr. Brosnan.