The effect of oral pregabalin on the minimum alveolar concentration of isoflurane in cats.

OBJECTIVE: To investigate the effect of three different doses of oral pregabalin on minimum alveolar concentration of isoflurane (MACISO) in cats. STUDY DESIGN: Prospective, randomized, placebo-controlled, blinded, crossover trial. ANIMALS: A group of eight healthy adult cats aged 24-48 months. METHODS: Cats were randomly assigned to three oral doses of pregabalin (low dose: 2.5 mg kg-1, medium dose: 5 mg kg-1, high dose: 10 mg kg-1) or placebo 2 hours before MACISO determination, with the multiple treatments administered with a minimum 7 day washout period. Anesthesia was induced and maintained with isoflurane in oxygen until endotracheal intubation was achieved, and maintained with isoflurane with volume-controlled ventilation. MACISO was determined in triplicate using the bracketing technique and tail clamp method 120 minutes after pregabalin or placebo administration. Physiologic variables (including heart rate and blood pressure) recorded during MACISO determination were averaged and compared between the pregabalin and placebo treatments. One-way analysis of variance and the Friedman test were used to assess the difference for normally and non-normally distributed data, respectively. The Tukey test was used as a post hoc analysis. Values of p < 0.05 were considered significant. RESULTS: The MACISO with the medium- and high-dose pregabalin treatments were 1.33 ± 0.21% and 1.23 ± 0.17%, respectively. These were significantly lower than MACISO after placebo treatment (1.62 ± 0.13%; p = 0.014, p < 0.001, respectively), representing a decrease of 18 ± 9% and 24 ± 6%. The mean plasma pregabalin concentration was negatively correlated with MACISO values. Physiologic variables did not differ significantly between treatments. CONCLUSIONS AND CLINICAL RELEVANCE: Doses of 5 or 10 mg kg-1 pregabalin, administered orally 2 hours before determining MACISO, had a significant isoflurane-sparing effect in cats.

Effect of oral administration of gabapentin on the minimum alveolar concentration of isoflurane in cats.

Objective: To determine if oral gabapentin decreases the minimum alveolar concentration (MAC) of isoflurane in cats. Study design: Prospective, randomized, blinded, crossover, and experimental study. Animals: A total of six healthy adult cats (three male, three female) aged 18-42 months, weighing 3.31 ± 0.26 kg. Methods: Cats were randomly given oral gabapentin (100 mg cat-1) or placebo 2 h before starting MAC determination, with the crossover treatment given at least 7 days apart. Anesthesia was induced and maintained with isoflurane in oxygen. Isoflurane MAC was determined in duplicate using an iterative bracketing technique and tail clamp method. Hemodynamic and other vital variables were recorded at each stable isoflurane concentration and were compared between gabapentin and placebo treatments at lowest end-tidal isoflurane concentration when cats did not respond to tail clamping. A paired t-test was used to compare normally distributed data, and a Wilcoxon signed-rank test was applied for non-normally distributed data. Significance was set at p < 0.05. Data are mean ± standard deviation. Results: Isoflurane MAC in the gabapentin treatment was 1.02 ± 0.11%, which was significantly lower than that in the placebo treatment (1.49 ± 0.12%; p < 0.001), decreasing by 31.58 ± 6.94%. No significant differences were found in cardiovascular and other vital variables between treatments. Conclusion and clinical relevance: Oral administration of gabapentin 2 h before starting MAC determination had a significant isoflurane MAC-sparing effect in cats with no observed hemodynamic benefit.