Amphetamine Extended-Release Tablets in the Treatment of Adults With ADHD

Inclusion Criteria 1. Male or female aged 18 to 60 years, inclusive at the time of Screening. 2. Diagnosed with ADHD using the DSM-5 criteria based on the Adults ADHD Clinical Diagnostic Scale (ACDS). 3. IQ within normal range based upon clinical opinion of the Investigator. 4. Baseline AISRS total score greater than or equal to 26. 5. Baseline score of 4 or higher in CGI-S. 6. Females who participate in this study will be of childbearing or non-childbearing potential: * Childbearing potential: Physically capable of becoming pregnant * Non-childbearing potential: * Permanently sterile (i.e., both ovaries removed, uterus removed, or bilateral tubal ligation for at least 6 weeks or documented successful hysteroscopic sterilization); and/or * Post-menopausal (no menstrual period for at least 12 consecutive months without any other medical cause). 7. Females of childbearing potential must be non-lactating and must have a negative serum pregnancy test at Screening. 8. Willing to use acceptable, effective methods of contraception. 9. Be able to attend the clinic regularly and reliably. 10. Be able to understand, read, write, and speak English fluently to complete the study related materials. 11. Be informed of the nature of the study and give written consent prior to any study procedure. Exclusion Criteria: 1. Current or lifetime history of bipolar disorder or any psychotic disorder as established by Mini International Neuropsychiatric Interview (M.I.N.I.) 7.0.2. 2. Current history of major depression, generalized anxiety disorder, obsessive-compulsive disorder, panic disorder, or post-traumatic stress disorder as established by the M.I.N.I. 7.0.2. 3. Known history of chronic medical illnesses including untreated thyroid disease, peripheral vasculopathy, known structural cardiac disorders, serious cardiac conditions, serious arrhythmias, cardiomyopathy, and known family history of sudden death. 4. History of uncontrolled hypertension or a resting systolic blood pressure \>140 mmHg or diastolic blood pressure \>90 mmHg. Subjects with well-controlled hypertension on a stable dose for at least 3 months of anti-hypertensives will be allowed to participate. 5. Have clinically significant findings in vital signs measurements at Screening including: * Systolic blood pressure \>140 mmHg or diastolic blood pressure \>90 mmHg * Heart rate \>100 bpm 6. Known history or presence of significant renal or hepatic disease, as indicated by clinical laboratory assessment: * Liver function test results ≥2 times the upper normal limit * Abnormal blood urea nitrogen, or creatinine levels 7. Clinically significant abnormal electrocardiogram or cardiac findings on physical examination (including the presence of a pathologic murmur). 8. Use of the following medications within 14 days of Baseline Visit: * Atomoxetine * Monoamine oxidase inhibitors (e.g., selegiline, isocarboxazid, phenelzine, tranylcypromine) * Tricyclic antidepressants (e.g., desipramine, protriptyline). 9. Use of the following medications within 3 days of Baseline Visit: * Gastrointestinal acidifying agents (e.g., guanethidine, reserpine, glutamic acid hydrochloride \[HCl\], ascorbic acid) * Urinary acidifying agents (e.g., ammonium chloride, sodium acid phosphate, methenamine salts). 10. Use of fluoxetine within 30 days of Baseline Visit. 11. Use of stimulant medications within 1 week of Baseline Visit. 12. Planned use of prohibited drugs or agents from the Screening visit through the end of the study. 13. Participation in a clinical study in which an investigational drug was administered within 30 days prior to Screening. 14. Abnormal clinically significant laboratory test values at Screening that, in the opinion of the Medical Monitor or Sponsor, would preclude study participation. 15. Known history of allergy/hypersensitivity to amphetamine or any of the components of AMPH ER TAB. 16. Known history of lack of clinical response to amphetamine based upon Investigator judgment. 17. Positive test result for HIV, Hepatitis B surface antigen, or Hepatitis C antibody. 18. Any uncontrolled medical condition that, in the opinion of Medical Monitor or Sponsor, would preclude study participation. 19. History or presence of alcohol dependence or substance abuse disorder according to DSM-5 or within the last 12 months. 20. Subject's inability or unwillingness to follow directions from the study research staff. 21. Answer of "yes" to questions 4 or 5 of the C-SSRS within the last 2 years.