Study to Evaluate NRCT-101SR in Adult Attention Deficit Hyperactivity Disorder (ADHD)

This is a multi-center, randomized, double-blind, placebo-controlled, parallel-arm design, laboratory classroom (LC) trial to assess the efficacy and safety of NRCT-101SR compared to inactive placebo for the treatment of ADHD in adults aged 18 years and older. After Screening, Orientation, and Baseline evaluations are complete, eligible subjects will be randomized into one of two groups (1:1) to receive NRCT-101SR or matching placebo orally twice daily, in the morning and evening, beginning the day after the Baseline visit for 6 weeks. Subjects will receive a fixed dose of 1,500 or 2,000 mg/day, based on lean body mass, split evenly between the morning and evening dosing. Total subject participation in the study is up to approximately 13 weeks, including a screening period (up to 6 weeks), a 6-week treatment period, and an approximate 1-week follow-up period. Within 8 days prior to Baseline LC visit, subjects will complete an LC Orientation Visit. LC visits will be repeated at Week 3 and Week 6. The primary outcome measures of the study include Permanent Product Measure of Performance (PERMP) Math Tests (number of correctly answered problems; PERMP-C) and ADHD Investigator Symptom Rating Scale (AISRS). At Baseline, Week 3 visit, and Week 6 visit, serial PERMP Math Tests at pre-dose and at 2, 4, 6, 8, 10, and 12 hours post-dose, and AISRS will be administered. LC visits will be repeated at Week 3 and Week 6. Secondary and exploratory assessments will also be conducted at the Baseline, Week 3, and Week 6 LC visits. A clinic visit will be conducted at Week 1. Pharmacokinetic (PK) sampling will be collected at the Week 3 LC visit. Safety assessments (concomitant medications, adverse events, and suicide risk) will be conducted at all clinic and remote visits/phone calls (Week 5, and follow-up); safety labs will be conducted at screening, Week 3, and Week 6.