A randomised controlled trial on the efficacy and side-effect profile (nausea/vomiting/sedation) of morphine-6-glucuronide versus morphine for post-operative pain relief after major abdominal surgery

During the first 24 h, nausea levels showed a 27% difference in favour of M6G which narrowly failed to reach statistical significance (P = 0.052). Sub-analysis showed a significant reduction in nausea levels in females on M6G (30% difference, P = 0.034). In all patients, similar reductions of 30-35% were observed in anti-emetic use, vomiting, PONV (a combined measure of nausea and vomiting) in favour of M6G, persisting for the first 24 h postoperatively. Reductions in sedation were observed in the first 4 h post-operative period for M6G patients.