Background: Amantadine sulfate is both a dopamine agonist and N-methyle-D-Aspartate (NMDA) antagonist which can augment the levels of dopamine in the striate body by triggering dopamine release and inhibiting dopamine reuptake. This study evaluated the effects of amantadine sulfate as a dopamine agonist on intraoperative wake up test duration and as a NMDA antagonist on cumulative opioid consumption 48h after surgery.

Methods: A randomized controlled double blind study, where 60 ASA class I and/or II patients of both sexes, planned for spine deformity corrective surgery were enrolled and divided into two groups (30 patients each):  Group A received intravenous (IV) amantadine sulfate infusion (200 mg), and Group B received Ringer’s lactate IV infusion.

Results: Forty-eight hours after surgery, morphine consumption in group A was significantly lower than that in Group B (21.24 ±1.1 vs. 30.41±2.12 P <0.001). Dynamic visual analog scale score was lower group A than that in group B (0.8±0.71 vs. 2.7±0.84 P <0.001). Moreover, anesthetic consumption in group A was lower than that in group B; however, no statistical difference in wake-up test duration or recovery time from anesthesia was found between both groups.

Conclusions: Preoperative administration of amantadine sulfate decreases postoperative morphine consumption and dynamic VAS score in patients undergoing corrective spine surgery. However, despite being a dopamine agonist, amantadine has no effect on wake- up test duration.

Keywords:  amantadine sulfate, dopaminergic pathway, dopamine induced arousal, opioid consumption, wake up test.