['attention deficit hyperactivity disorder']
['hld200', 'placebo']

        Inclusion Criteria:

          -  Male and female children (6-12 years at study entry)

          -  Previous diagnosis of ADHD and confirmation using the Mini International
             Neuropsychiatric Interview for Children and Adolescents (MINI-KID)

          -  Able to swallow treatment capsules

          -  Available for entire study period

          -  Provision of informed consent (from the parent[s] and/or legal representative[s]) and
             assent (from the subject)

          -  Female subjects of childbearing potential (i.e., post-menarche) required to have a
             negative result on urine pregnancy test (and will be given specific instructions for
             avoiding pregnancy during trial).

        Exclusion Criteria:

          -  Any known history or presence of significant cardiovascular, pulmonary, hepatic,
             renal, hematologic, gastrointestinal, endocrine, immunologic, dermatologic,
             neurologic, ophthalmologic disease

          -  Presence of any significant physical or organ abnormality

          -  Any illness during the 4 weeks before this study

          -  Comorbid psychiatric diagnosis that may affect subject safety or confound results
             (e.g., psychosis, bipolar disorder)

          -  Known history of severe asthma (in the opinion of the investigator) unless deemed
             currently controlled

          -  Known history of severe allergic reaction to MPH

          -  Known history of seizures (except febrile seizures prior to age 5), anorexia nervosa,
             bulimia or current diagnosis or family history of Tourette's disorder

          -  Subject who are severely underweight or overweight (in the opinion of the
             Investigator)

          -  Any clinical laboratory value outside of the acceptable ranges, unless deemed NCS
             significant per the Investigator

          -  Positive history for hepatitis B, hepatitis C or Human Immunodeficiency Virus (HIV)

          -  Positive screening for illicit drug use, and/or current health conditions or use of
             medications that might confound the results of the study or increase risk to the
             subject

          -  Use of prescription medications (except ADHD medications) within 7 days and
             over-the-counter medications (except birth control) within the 3 days preceding study
             enrollment, unless deemed acceptable by the Investigator and Clinical or Medical
             Monitor

          -  Participation in clinical trial with an investigational drug within the 30 days
             preceding study enrollment

          -  Current suicidal ideation or history of suicidality determined as a significant
             finding on the C-SSRS by the investigator (Baseline C-SSRS for adolescents; Pediatric
             Baseline C-SSRS for children).
      