Safety and Tolerability Study of SHP465 in Children Aged 4 to 12 Years Diagnosed With Attention-deficit/Hyperactivity Disorder (ADHD)

The purpose of the study is to evaluate the long-term safety and tolerability of SHP465 at 6.25 milligram (mg) in children aged 4 to 12 years diagnosed with Attention-Deficit/Hyperactivity Disorder (ADHD).


Eligibility Criteria:
Inclusion Criteria:

* Participant is male or female aged 4-12 years inclusive at the time of consent.
* Participant's parent or legally authorized representative (LAR) must provide signature of informed consent, and there must be documentation of assent (as applicable) by the participant.
* Participant must meet Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) criteria for a primary diagnosis of ADHD (any subtype).
* Participant who is a female and of child-bearing potential must not be pregnant and agree to comply with any applicable contraceptive requirements..
* Participant has an ADHD-RS-5 Child, Home Version Total Score of greater than or equal to (\>=) 28 and Clinical Global Impression - Severity of Illness (CGI-S) score \>=4 at baseline (Visit 2). Participant is currently not on ADHD therapy, or is not completely satisfied with their current ADHD therapy.

Exclusion Criteria:

* Participant is required or anticipated to take medications that have central nervous system effects or affect performance. Stable use of bronchodilator inhalers is not exclusionary.
* Participant has a concurrent chronic or acute illness, disability, or other condition that might confound the results of safety assessments conducted in the study or that might increase risk to the participant. - Participant has a documented allergy, hypersensitivity, or intolerance to amphetamine or to any excipients in the investigational product.
* Participant has failed to fully respond, based on investigator judgment, to an adequate course of amphetamine therapy.
* Participant has a known family history of sudden cardiac death or ventricular arrhythmia.
* Participant has a blood pressure measurement \>=95th percentile for age, sex, and height at screening (Visit 1) and/or baseline (Visit 2).
* Participant has a height less than or equal to (\<=) 5th percentile for age and sex at screening (Visit 1) or baseline (Visit 2).
* Participant has a weight \<=5th percentile for age and sex at screening (Visit 1) or baseline (Visit 2).
* Participant has a known history of symptomatic cardiovascular disease, structural cardiac abnormality, cardiomyopathy, serious heart rhythm abnormalities, or other serious cardiac conditions placing them at increased vulnerability to the sympathomimetic effects of a stimulant drug.
* Participant has a history of seizures (other than infantile febrile seizures).
* Participant is taking any medication that is excluded per the protocol.
* Participant had any clinically significant ECG or clinical laboratory abnormalities at the screening (Visit 1) or baseline visit (Visit 2).
* Participant has current abnormal thyroid function, defined as abnormal thyroid-stimulating hormone and thyroxine at the screening or baseline visit. Treatment with a stable dose of thyroid medication for at least 3 months is permitted.
* Participant is currently considered a suicide risk in the opinion of the investigator, has previously made a suicide attempt, or has a prior history of or currently demonstrating suicidal ideation.