Pregabalin Has Analgesic, Ventilatory, and Cognitive Effects in Combination with Remifentanil.

BACKGROUND Pregabalin is widely used perioperatively. The authors explored the effects of pregabalin, remifentanil, and their combination on experimental pain, ventilatory, and cognitive function. METHODS In a randomized, double-blinded crossover study, 12 volunteers received (1) pregabalin + placebo, (2) placebo + remifentanil, (3) pregabalin + remifentanil, and (4) placebo + placebo. Pregabalin 150 mg/placebo was administered twice orally. After baseline, remifentanil/placebo was given as effect-site target-controlled infusion (TCI): 0.6, 1.2, and 2.4 ng/ml. Pain during cold pressor test was scored on visual analog scale (0 to 100 mm). Ventilation was measured by spirometry and cognition tested with Color-Word Interference and Rapid Information Processing tests. RESULTS Pain intensity after placebo was (mean) 72 mm (95% CI, 62 to 83). Pregabalin reduced pain score by -10 mm (-14 to -7, P < 0.001). Remifentanil had dose-dependent analgesic effect, reducing pain score by -47 mm (-54 to -39, P < 0.001) on highest TCI level, whereas pregabalin + remifentanil exerted additive effect, reducing pain score by -57 mm (-64 to -50, P < 0.001). Respiratory depression was potentiated by adding pregabalin to remifentanil; end-tidal carbon dioxide was 39.3 mmHg (37.2 to 41.3) with placebo, increased 1.8 mmHg (-0.9 to 4.6, P = 0.4) with pregabalin, 10.1 mmHg (4.9 to 15.4, P < 0.001) with remifentanil, and 16.4 mmHg (11.3 to 21.5, P < 0.001) with pregabalin + remifentanil on highest TCI level. The combination pregabalin + remifentanil, but not either drug alone, adversely affected all cognitive tests. CONCLUSIONS The combination of pregabalin and remifentanil had additive analgesic effects, pregabalin potentiated remifentanil ventilatory depression, and the combination adversely affected cognition. These results question the clinical benefit of the combination compared with higher doses of opioids.