Modulation of Paracetamol and Nefopam Antinociception by Serotonin 5-HT3 Receptor Antagonists in Mice

BACKGROUND/AIMS: Post-operative nausea and vomiting are common adverse events that require administration of anti-emetic compounds, such as the serotonin 5-HT(3) receptor antagonists, but these drugs can also reduce the analgesic efficacy of some analgesics (paracetamol, tramadol). METHODS: The present study was designed to explore the effect of 3 serotonin 5-HT(3) receptor antagonists on the antinociceptive efficacy of another frequently used post-operative analgesic, nefopam, in the mouse writhing and formalin tests. RESULTS: Pre-treatment with tropisetron, ondansetron or MDL72222 did not significantly modify nefopam antinociception in both tests. However, paracetamol antinociception was blocked by ondansetron in the formalin test. CONCLUSION: These results provide a rationale for the clinical use of nefopam with anti-emetics during surgery.