JPRN‐UMIN000017876.

Study name	Effects of long‐term administration of intranasal oxytocin in children with autism spectrum disorder
Methods	14‐week cross‐over trial of oxytocin versus placebo
Participants	Inclusion criteria: male aged 6‐10 years diagnosis of ASD based on DSM‐5 criteria and further confirmed by ADOS at Osaka university hospital IQ 35‐75 parents provide written informed consent to participate Exclusion criteria female co‐occurring cardiovascular or renal disease allergy to oxytocin previously used oxytocin doctors judged the trial to be inappropriate for the patient. Location/setting: Japan Target sample size: 10 in total
Interventions	Intervention: intranasal oxytocin 24 IU twice daily, followed by a 1‐week wash‐out period before phase 2 of the trial. Comparator: equivalent intranasal placebo twice daily, followed by a 1‐week wash‐out period before phase 2 of the trial.
Outcomes	Primary outcomes: ABC‐I subscale (Japanese version) AEs Secondary outcomes: none reported Timing of outcome assessments: baseline and endpoint of phase
Starting date	First registered June 2015
Contact information	Contact person: Masako Taniike Contact details: masako@ped.med.osaka‐u.ac.jp
Notes	Source of funding: sponsored by the United Graduate School of Child Development, Osaka University Conflicts of interest: details not provided