Safety and Tolerability Study of SPD489 in Preschool Children Aged 4-5 Years, Diagnosed With Attention-deficit/Hyperactivity Disorder

Inclusion Criteria

• Participant is male or female aged 4-5 years inclusive at the time of consent from antecedent studies SPD489-211 or SPD489-347 or at the time of consent if directly enrolled.
• Before completing any study-related procedures, participant's parent(s) or legally authorized representative (LAR) must provide signature of informed consent, and there must be documentation of assent (if applicable) by the participant indicating that the participant is aware of the investigational nature of the study. The participant's parent(s) or LAR should understand that the required procedures and restrictions are being conducted in accordance with the International Council of Harmonisation (ICH) Good Clinical Practice (GCP) Guideline E6 (1996), any updates or revisions, and applicable federal or local regulations.
• Participant and parent(s)/LAR are willing and able to comply with all of the testing and requirements defined in the protocol, including oversight of morning dosing. Specifically, the parent/LAR should be available at approximately 7:00AM (+2 hours) to dispense the dose of investigational product for the duration of the study.
• Roll-over participant from antecedent SPD489-347 study:

a. Participant completed the antecedent study (SPD489-347)

• Direct enrolled participants must meet antecedent study inclusion criteria, as listed below
• Participant must meet Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV-TR) criteria for a primary diagnosis of ADHD (any subtype) based on a detailed psychiatric evaluation conducted by a sponsor-approved clinician
• Participant has an attention-deficit/hyperactivity disorder rating scale- IV (ADHD-RS-IV) Preschool Version total score at the Baseline Visit (Visit 0) of greater than equals to (>=) 28 for boys and >= 24 for girls.
• Participant has a Clinical Global Impressions - Severity of Illness (CGI-S) score >=4 at the Baseline Visit (Visit 0).
• Participant has a Peabody Picture Vocabulary Test, Fourth Edition standard score of >=70 at the Screening Visit (Visit -1).
• Participant has undergone an adequate course of non-pharmacological treatment based on investigator judgment or the participant has a severe enough condition to consider enrollment without undergoing prior non-pharmacological treatment, based on investigator judgment.
• Participant has, in the opinion of the investigator, participated in a structured group activity (eg, preschool, sports, Sunday school) so as to assess symptoms and impairment in a setting outside the home.
• Participant has lived with the same parent(s) or guardian for >=6 months.

Exclusion Criteria

• Participant was terminated from an antecedent SPD489 study for non-compliance and/or experienced a serious adverse event (SAE) or adverse event (AE) resulting in termination.
• Participant is required to or anticipates the need to take medications that have central nervous system effects or affect performance, such as, but not limited to, sedating antihistamines and decongestant sympathomimetics, or monoamine oxidase inhibitors. Stable use of bronchodilator inhalers is not exclusionary.
• Participant has a concurrent chronic or acute illness (such as, but not limited to, severe allergic rhinitis or an infectious process requiring antibiotics), disability, or other condition that might confound the results of safety assessments conducted in the study or that might increase risk to the participant. Similarly, the participant will be excluded if he or she has any additional condition(s) that, in the investigator's opinion, would prohibit the participant from completing the study or would not be in the best interest of the participant. The additional condition(s) would include any significant illness or unstable medical condition that could lead to difficulty complying with the protocol. Mild, stable asthma is not exclusionary.
• Participant has a documented allergy, hypersensitivity, or intolerance to