Charuluxananan 2003.

Study characteristics
Methods	RCT
Participants	240 ASA 1‐2 women undergoing CS under spinal anaesthesia without allergy to study drugs, pruritis, skin disease.
Interventions	Intervention 1: opioid antagonist (Comparison 7) Nalbuphine 4 mg. N = 60. Intervention 2: 5‐HT3antagonist (Comparson 1) Ondansetron 4 mg. N = 60. Intervention 3: 5‐HT3antagonist (Comparson 1) Ondansetron 8 mg. N = 60. Comparator: placebo. Normal saline. N = 60.
Outcomes	Pruritis, post‐op nausea and vomiting, adverse effects.
Notes	Setting: King Chulalongkorn Memorial Hospital, Bangkok, Thailand. Dates: not reported Funding source: not reported Declaration of interest: not reported In Comparison 1, data in Groups 2 and 3 were entered as subgroups and combined with overall data for treatment effect with the required adjustment of the placebo data for the 2 subgroups according to our methods (Unit of analysis issues)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Random number table.
Allocation concealment (selection bias)	Low risk	Sealed envelopes and randomly allocated coded syringes were prepared by a nurse anaesthetist not involved with the study
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Quote:"double blind" but not specifically described
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Quote:"double blind" but not specifically described
Incomplete outcome data (attrition bias) All outcomes	Low risk	None described.
Selective reporting (reporting bias)	Unclear risk	We did not assess the trial protocol.
Other bias	Unclear risk	No baseline differences.