An Efficacy Study of Osmotic Release Oral System (OROS) Methylphenidate in Participants With Attention-Deficit/Hyperactivity Disorder (ADHD)

The purpose of this study is to evaluate the efficacy, tolerability and effects of Osmotic Release Oral System (OROS) methylphenidate hydrochloride (HCl) on learning skill changes in Korean participants with Attention-Deficit Hyperactivity Disorder (ADHD).

This is 12 week, open label (all people involved know the identity of the intervention), prospective (study following participants forward in time), single arm, multicenter study (when more than one hospital or medical school team work on a medical research study) of OROS methylphenidate HCl. The study will consist of 6 visits at Screening, Baseline, Week 1, 3, 6 and 12. The participants already on other ADHD medications in addition to methylphenidate will be required to undergo a washout period (period when receiving no treatment) of at least 1 week. The participants will be on once daily study medication starting at 18 milligram per day (mg/day) in participants with less than 30 kilogram (kg) of body weight or at 27 mg/day in participants with more than 30 kg. The dose will be increased by 9 mg or 18 mg every week for up to Week 6 based on the treatment efficacy and tolerability, followed by a maximum maintenance dose of 72 mg orally once daily up to Week 12, during which the dose can be decreased by 9 mg depending on tolerability. Efficacy will primarily be assessed using Clinical Global Impression of Severity of Illness (CGI-S) scale, Clinical Global Impression of Improvement of Illness (CGI-I) scale, Korean version of ADHD-IV Rating Scale (K-ARS) and Learning Skill Test (LST) score. Participants' safety will be monitored.

Eligibility Criteria:
Inclusion Criteria:

* Participants must meet Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) criteria for Attention Deficit Hyperactivity Disorder (ADHD) and are considered to require medication therapy
* Participants that agreed to observe visit schedules and willingly complete the evaluation defined by participant (possibly to be completed by parents/guardians) during the treatment period
* Participants and parents/guardians that are able to understand the participation procedures of the research and spontaneously request the discontinuation therein at any time
* Participants that offered spontaneous consent for participation
* Participants whose guardian/legal representative provided spontaneous written consent

Exclusion Criteria:

* Hypersensitivity to methylphenidate HCl
* Participants diagnosed with major depression or anxiety disorders according to DSM-IV Diagnostic criteria and who requires drug therapy
* Participants with a history of bipolar disorder, psychotic disorder, and substance abuse disorder ordiagnosed with an overall developmental disorder, organic brain disorder, seizure (sudden, uncontrolled muscle spasms and loss of consciousness resulting from abnormal brain function) disorder, movement disorder requiring the medication therapy, or with a family history of Tourette's syndrome (a neuropsychological disorder that causes marked distress or significant impairment in social, occupational, or other important areas of functioning)
* Taken Osmotic Release Oral System (OROS) Methylphenidate within 3 months prior to screening
* Currently taking alpha-2 adrenergic receptor agonist, antidepressant, antipsychotic, benzodiazepines, modafinil, anticonvulsant (drug used to stop seizures) or health food supplements that may have a central nervous system activity