Arnold 2004.

Methods	A 7‐centre US study consisting of a 6‐week, open‐label, dose‐titration phase (Part A) and a 2‐week, double‐blind, randomised, parallel, placebo‐controlled withdrawal study (Part B) with 2 arms: Dexmethylphenidate Placebo
Participants	Part A Number of participants screened: 116 Number of participants included: 89 Number of participants followed up: 76 Number of withdrawals: 13 Diagnosis of ADHD: DSM‐IV (subtype: combined (80%)) Age: range 6‐16 years old Sex: 72 males, 17 females IQ: not stated Methylphenidate‐naïve: 71,9% Ethnicity: not stated Country: USA Comobidity: not stated Comedication: not stated Sociodemographics: not stated Inclusion criteria 6‐17 years of age Enrolled in school DSM‐IV diagnosis of ADHD any subtype Within 30% of normal body weight Able to participate for the full 8 weeks Exclusion criteria History or evidence of cardiovascular, renal, respiratory (other than asthma/allergy), endocrine, or immune system disease History of substance abuse Hypersensitivity to dl‐methylphenidate or other stimulants Treatment with any investigational drug within 30 days of screening Other significant central nervous system disorders Treatment with antidepressants, neuroleptics/ antipsychotics, mood stabilisers, anticonvulsants, beta blockers, alpha2 agonists, other stimulants, thyroid medications, chronic oral steroids, or sedatives/hypnotics Concurrent treatment with other psychoactive drug
Interventions	Part A Methylphenidate type: dexmethylphenidate Methylphenidate dosage: 2.5 to 10 mg twice daily depending on individual participants' prior medication experience Children who had received dl‐MPH began with half their total daily dl‐MPH dose administered as d‐MPH, but not more than 20 mg/day; those who had not previously received dl‐MPH started d‐MPH at 2.5 mg twice daily Duration of intervention: 6 week Treatment compliance: not stated
Outcomes	Non‐serious adverse events: Part A and B: monitoring AEs and changes from baseline in vital signs (pulse and blood pressure), physical examination, and clinical laboratory parameters throughout the study
Notes	Sample calculation: not stated Ethics approval: not stated Funding: not stated Vested interests/authors' affiliations: Key conclusions of the study authors: d‐MPH is safe, tolerable, and effective, with a 6‐hour duration of effect suggested by the significant difference from placebo at 6 hours on a double‐blind discontinuation Comments from the study authors: limitations: study design (withdrawal): treatment effects in such trials may be larger than those seen in unselected populations, because randomised, withdrawal phase preselected responders to the drug from the open‐label titration phase. Another possible limitation is the duration of the discontinuation (2 weeks) Supplemental information received through email correspondence with the authors in October 2013 (Arnold 2013b [pers comm]) However, authors advise us to contact the sponsoring drug company for additional information. We contacted them in November 2013 (Jones 2013 [pers comm]), but did not succeed in getting further information.