The effects of intravenous gabapentin administration on the minimum alveolar concentration of isoflurane in cats.
BACKGROUND
Gabapentin is a structural analog of gamma-aminobutyric acid, one of the inhibitory neurotransmitters of the mammalian central nervous system. It is increasingly being used preemptively to control postoperative pain. Therefore, its interaction with inhaled anesthetics is of clinical interest. In this study, we examined the effects of gabapentin on the minimum alveolar concentration (MAC) of isoflurane in cats. We hypothesized that gabapentin would decrease the MAC of isoflurane in a dose-dependent manner.


METHODS
Six cats were included in the study. Gabapentin was administered IV to achieve target plasma concentrations between 0 and 16 microg/mL and the MAC of isoflurane was determined at each gabapentin concentration. Gabapentin concentrations were quantitated by liquid chromatography-mass spectrometry analysis of extracted plasma samples. MAC values at the different gabapentin plasma concentrations were analyzed by a repeated-measures analysis of variance using the Huynh-Feldt correction for violation of the sphericity assumption.


RESULTS
Actual gabapentin concentrations were 0 + or - 0, 1.18 + or - 0.23, 2.25 + or - 0.23, 4.96 + or - 1.19, 10.63 + or - 1.37, and 19.69 + or - 3.97 microg/mL for the target concentrations of 0, 1, 2, 4, 8, and 16 microg/mL, respectively. The MAC of isoflurane in this study was 2.10% + or - 0.13%, 2.10% + or - 0.14%, 2.13% + or - 0.12%, 2.06% + or - 0.11%, 2.11% + or - 0.15%, and 2.09% + or - 0.25% at target plasma concentrations of 0, 1, 2, 4, 8, and 16 microg/mL, respectively.


CONCLUSIONS
We conclude that gabapentin did not have a detectable effect on the MAC of isoflurane in cats.
Reid
Patrick
P
Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, One Shields Ave., Davis, CA 95616, USA.
Pypendop
Bruno H
BH
Ilkiw
Jan E
JE
D000588:Amines / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D000700:Analgesics / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D000769:Anesthesia, Inhalation; D018685:Anesthetics, Inhalation / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001831:Body Temperature / Q000187:drug effects; D002415:Cats; D002851:Chromatography, High Pressure Liquid; D003509:Cyclohexanecarboxylic Acids / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D000077206:Gabapentin; D007275:Injections, Intravenous; D007530:Isoflurane / Q000008:administration & dosage / Q000494:pharmacology*; D011650:Pulmonary Alveoli / Q000378:metabolism*; D053719:Tandem Mass Spectrometry; D005680:gamma-Aminobutyric Acid / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*
D000588:Amines; D000700:Analgesics; D018685:Anesthetics, Inhalation; D003509:Cyclohexanecarboxylic Acids; D005680:gamma-Aminobutyric Acid; D000077206:Gabapentin; D007530:Isoflurane