Ondansetron versus ondansetron with dexamethasone to prevent intrathecal-morphine pruritus for caesarean patients: randomised double-blind trial.

The objective of this randomised, double blinded clinical trial was to evaluate the efficacy of prophylactic administration of 4 mg ondansetron as monotherapy versus combination therapy of 4 mg ondansetron plus 8 mg dexamethasone for the prevention of intrathecal morphine-associated pruritus in caesarean section within 24 h. A total of 194 patients were included, 96 patients in the monotherapy group and 98 in the combination group. One hour after the operation, 11.5% of patients in ondansetron group had failure of prophylaxis for pruritus compared to 13.5% of patients in the combination group (p = .66). This decreased throughout the follow-up to reach 0.0% and 1.0% at 24 h in the ondansetron vs. the combination groups respectively. There was no superiority of combining ondansetron with dexamethasone over the use of ondansetron as prophylactic antipruritic in parturients receiving intrathecal morphine for caesarean section.IMPACT STATEMENTWhat is already known on this subject? The incidence of pruritus has been reported to be between 36% and 60% in patients undergoing caesarean section with intrathecal morphine. Ondansetron has been identified as possible antipruritic agent while the antipruritic effect of dexamethasone is inconclusive.What do the results of this study add? The study demonstrated that there was no superiority of combining ondansetron with dexamethasone over the use of ondansetron as prophylactic antipruritic in parturients receiving intrathecal morphine for caesarean section. Moreover, it seems that there is no effect of combining ondansetron with dexamethasone over ondansetron alone on antiemetic consequences.What are the implications of these findings for clinical practice and/or further research? Ondansetron could be an effective antipruritic if used solely for patients undergoing caesarean section.