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 (MAC_ISO) 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 MAC_ISO 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. MAC_ISO 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 MAC_ISO 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 MAC_ISO with the medium- and high-dose pregabalin treatments were 1.33 ± 0.21% and 1.23 ± 0.17%, respectively. These were significantly lower than MAC_ISO 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 MAC_ISO 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 MAC_ISO, had a significant isoflurane-sparing effect in cats.