UMIN000017876.

Study name	Effects of long‐term administration of intranasal oxytocin in children with autism spectrum disorder
Methods	4‐week cross‐over trial of oxytocin versus placebo
Participants	Inclusion criteria: male participants aged 6‐10 years diagnosis of ASD based on the DSM‐V IQ 35‐75 written informed consent provided by the parent/s Exclusion criteria: comorbid renal or cardiovascular disease allergy to oxytocin female previous use of oxytocin Setting/location: Japan Sample size: target sample size is 10
Interventions	Intervention (oxytocin for 4 weeks followed by placebo): 24 IU of oxytocin twice daily for 4 weeks, then 1‐week washout followed by 4 weeks of placebo Comparator (placebo for 4 weeks followed by oxytocin): placebo for 4 weeks followed by 1‐week washout period then 4 weeks of 24 IU oxytocin twice daily
Outcomes	Primary outcomes: irritability, measured using the ABC‐J (Japanese version of ABC‐Irritability) (Aman 1985) adverse effects Secondary outcomes: unclear Timing of outcome assessments: unclear
Starting date	Registered in 2015
Contact information	Name: Masako Taniike E‐mail: masako@ped.med.osaka‐u.ac.jp
Notes	Source of funding: unclear

ABC‐I: Aberrant Behaviour Checklist: Irritability subscale; ADOS: Autism Diagnostic Observation Schedule; AE: adverse effect; ASD: Autism Spectrum Disorder; BoC: behaviours of concern; DSM:IV: Diagnostic and statistical Manual of Mental disorders (4th edition); DSM‐V: Diagnostic and statistical Manual of Mental disorders (5th edition); ICD‐10: International classification of diseases (10th edition); IGF‐1: insulin‐like growth factor‐1; PedsQL: Pediatric Quality of Life inventory; QoL: quality of life