Effect of pre‐operative oral sustained‐release morphine sulfate on post‐operative morphine requirements in elective spine surgery

Background Sustained‐release morphine sulfate (SRMS) is a painkiller used in oncology. The purpose of our study was to assess its efficacy on post‐operative morphine requirements in elective spine surgery. Methods This was a placebo‐controlled, randomized, double‐blind study. Adults scheduled for spine surgery under general anaesthesia were orally administered SRMS (30 mg) or a placebo 2h before surgery. Primary endpoint was post‐operative cumulated morphine consumption through patient‐controlled analgesia (PCA) during the 12h following extubation. Statistical analysis was performed using a sequential method, the triangular test. Results The study was stopped after the sixth analysis (51 patients had been included; placebo: 26, SRMS: 25). Patients' characteristics were similar in the two groups. Morphine consumption through PCA during the 12h following extubation was significantly lower in SRMS group (mean±SD: 10.5±7.6 mg) compared to placebo group (15.6±6.0 mg, P =0.016, sequential analysis). Morphine consumption through PCA during the 24h following extubation was also significantly lower in SRMS group (15.9±12.7 mg) compared to placebo group (23.8±10.9 mg, P =0.032). Vigilance, nausea and respiratory rate 3 and 6h after extubation were similar in the two groups. Conclusion A pre‐operative oral administration of SRMS (30 mg) induces a 33% reduction of post‐operative morphine requirements in patients scheduled for spine surgery without inducing side effects. Clinical Pharmacology & Therapeutics (2005) 77 , P8–P8; doi: 10.1016/j.clpt.2004.11.033