Dextromethorphan and pain after total abdominal hysterectomy

Dextromethorphan is an N-methyl-D-aspartate (NMDA) receptor antagonistwhich has been shown to inhibit the development of cutaneous secondaryhyperalgesia after tissue trauma. We studied 60 ASA I-II patientsundergoing total abdominal hysterectomy in a randomized, double-blind,placebo-controlled study. Patients received either dextromethorphan 27 mgcapsules, two doses before operation and three doses in the first 24 hafter operation, or placebo. Visual analogue pain scores (VAS) at 24 and 48h were assessed at rest, on coughing and on sitting up, and were notsignificantly different between groups. Morphine consumption from apatient-controlled analgesia (PCA) device was also not significantlydifferent between groups. Evidence of secondary hyperalgesia was assessedwith von Frey hairs 10 cm above the Pfannenstiel incision. Both groups ofpatients exhibited evidence of secondary hyperalgesia after 24 and 48 h butthere were no significant differences between groups. There was also nodifference between groups in VAS scores at 1 month.