Randomized prospective study of the analgesic effect of nefopam after orthopaedic surgery.

Background: Balanced postoperative analgesia combines non-narcotic drugs and opioids. We organized a large study to evaluate nefopam analgesia and tolerance in combination with morphine for patient-controlled analgesia (PCA) after orthopaedic surgery.

Methods: Two hundred and one patients scheduled to undergo hip arthroplasty were included in this multicentre (n=24), double-blind, randomized study comparing nefopam (20 mg every 4 h for 24 h) with placebo, the first dose being infused peroperatively. The primary outcome measure was the cumulative morphine dose received postoperatively by PCA over 24 h. Secondary outcome measures were the amount of morphine received as a loading dose in the postanaesthesia care unit (PACU) and during the 24-h observation period, and pain assessments using a visual analogue scale (VAS) and a verbal pain scale (VPS), patient's satisfaction with analgesia and treatment tolerance.

Results: The two groups were comparable with respect to their characteristics and preoperative pain assessment. PCA-administered morphine over 24 h was significantly less for the nefopam group than the control group (21.2 (15.3) and 27.3 (19.2) mg respectively; P=0.02). This morphine-sparing effect was greater (35.1%) for patients with severe preoperative pain (VAS>30/100). For the entire study period (loading dose and PCA), morphine use was less for the nefopam group (34.5 (19.6) vs 42.7 (23.6) mg; P=0.01). Pain VAS at PACU arrival and during the whole PACU period was significantly lower for the nefopam than for the placebo group (P=0.002 and 0.04 respectively). Patient satisfaction was similar for the nefopam and placebo groups.

Conclusion: In combination with PCA morphine, nefopam gives significant morphine-sparing with lower immediate postoperative pain scores without major side-effects. This analgesic effect seems to be particularly notable for patients with intense preoperative pain.