Tropisetron and paracetamol association in post‐operative patients

Abstract

Studies in animals and in healthy volunteers have demonstrated the central serotonergic analgesic mechanism of action of paracetamol involving the inhibition of this analgesia by tropisetron, a 5-HT3 antagonist. This randomized, double-blind, controlled study aims at studying this interaction in post-operative patients after ear surgery. Thirty-six patients are included in two parallel groups with intravenous paracetamol (1 g) and either tropisetron (T, 5 mg/mL) or placebo (c, NaCl 0.9%) administered at the end of surgery. Numerical pain evaluations are performed every 30 min, six times after awakening. The difference between the sums of numerical scales of both groups [9 ± 10 (T) vs. 6 ± 7 (c)] is not significant, but the tropisetron group displays higher pain scores despite additional rescue analgesia. The limits of this trial call for a much larger study to investigate further this pharmacodynamic interaction.

The Effect of Paracetamol and Tropisetron on Pain: Experimental Studies and a Review of Published Data

“…These experimental findings were questioned in a clinical study, in which the analgesic action of paracetamol was not affected by ondansetron after hysterectomy [20]. Pickering et al [21] could not demonstrate any interaction between paracetamol and tropisetron after ear surgery. Paracetamol is used for post-operative and cancer-related pain, and 5HT3-antagonists are administered to prevent or manage post-operative and chemotherapy-induced nausea and vomiting.…”

Analgesic interaction between ondansetron and acetaminophen after tonsillectomy in children: The Paratron randomized, controlled trial

“…Therefore, co‐administration of acetaminophen with a setron could theoretically lead to a decrease or a loss of the analgesic properties of acetaminophen through a pharmacodynamic interaction at serotonin receptors (Tjolsen et al., ; Pelissier et al., ). Indeed, interactions between setrons and acetaminophen have been reported in different animal studies (Tjolsen et al., ; Alloui et al., ; Pelissier et al., ; Bonnefont et al., ; Girard et al., ) and in human volunteers (Pickering et al., ; Bandschapp et al., ), although this interaction has not been demonstrated in clinic settings (Jokela et al., ; Pickering et al., ).…”

The Contribution of Serotonergic Receptors and Nitric Oxide Systems in the Analgesic Effect of Acetaminophen: An Overview of the Last Decade

“…However, patients who received tropisetron and acetaminophen needed more rescue analgesic agent. 39 A randomized, double-blinded study showed that ondansetron (8 mg) reduced the analgesic effect of acetaminophen (1 g) in patients who had undergone abdominal hysterectomy; however, this reduction was in a short period of time. 40 The results of those human studies indicate that there is a questionable interaction between acetaminophen analgesia and 5-HT 3 blockers due to some conflicting results.…”

“…Those conflicting results, showing a lack of obvious interaction, were mainly related to post-operative pain conditions. 38,39 However, in healthy volunteers, the interaction between acetaminophen and 5-HT 3 blockers (tropisetron and granisetron) seems more obvious and is likely to be a pharmacodynamic interaction. [35][36][37] Apparently, studies with larger patient populations with different painful conditions are needed to clarify the interaction between 5-HT 3 blockers and acetaminophen in humans.…”