IRCT20200317046801N2.

Study name	Effect of ondansetron combination therapy with risperidone in children with autism spectrum disorder in a randomized, double‐blind, placebo‐controlled clinical trial
Methods	8‐week parallel trial of ondansetron versus placebo
Participants	Inclusion criteria: children aged 5‐17 years DSM‐V diagnosis of autism Exclusion criteria: any active medical condition any psychiatric conditions taking risperidone or other psychotropics in the 2 weeks prior to the study liver, heart, or kidney disease allergy to ondansetron Setting: Roozbeh Hospital, Tehran, Iran Target sample size: 40
Interventions	Intervention: risperidone and ondansetron (05 mg/kg/day for children > 40 kg) for 8 weeks Comparator: risperidone and placebo for 8 weeks ‐ the dosage of risperidone is unclear. Ondansetron: 05 mg/kg/day for children > 40 kg; placebo is 05 mg/kg/day for children > 40 kg
Outcomes	Primary outcomes: irritability, measured using the ABC‐I (Aman 1985) Secondary outcomes: unclear Timing of outcome assessments: baseline, weeks 4 and 8 (endpoint)
Starting date	11 September 2020
Contact information	Name: Rahim Badrfam E‐mail: rbadrfam@gmail.com
Notes	Source of funding: Tehran University of Medical Sciences Conflicts of interest: unclear