Preemptive levetiracetam decreases postoperative pain in rats.

Objectives: Preemptive versus therapeutic effects of levetiracetam were investigated in a model of postoperative incisional pain in rats.
Methods: Levetiracetam (250, 500, and 1000 mg/kg intraperitoneal (i.p.) or morphine (5 mg/kg i.p.) was administered either 1 h before (preemptive administration) or 1 h after (therapeutic administration) incisional surgery to the hind paw of rats. The effects of levetiracetam were evaluated based on thermal hyperalgesia measured by the plantar test.
Results: All preoperatively treated levetiracetam groups showed a significant, dose dependent, increase in paw withdrawal latency. However, post-incisional administration of levetiracetam produced no antihyperalgesic effect at any dose or at any time. In contrast, post-incisional administration of morphine reduced thermal hyperalgesia, while preemptive administration of morphine did not produce any significant antihyperalgesic effects.
Conclusion: The present results suggest that levetiracetam might possess preemptive analgesic activity.