Comparative Bioavailability of Trimodal (CTx-1301) Versus Bimodal Dexmethylphenidate Modified-Release Formulations in Adults with Attention-Deficit/Hyperactivity Disorder: A Randomized, Single-Dose, Crossover Study

Attention-deficit/hyperactivity disorder (ADHD) is a chronic neurodevelopmental disorder that often requires sustained symptom control throughout the day. Although bimodal extended-release dexmethylphenidate (d-MPH XR) formulations provide initial and intermediate drug release, they may not consistently maintain therapeutic exposure into the late afternoon and evening. Trimodal formulations with an additional delayed release component may extend drug exposure later in the day, although this remains to be established. To explore differences in pharmacokinetic (PK) profiles between trimodal (CTx-1301) and bimodal delivery of d-MPH XR, a comparative bioavailability study was conducted at the highest and lowest doses for both formulations. In this randomized, 4-period, crossover study, adults with ADHD received single doses of CTx-1301 (50 mg and 6.25 mg) and d-MPH XR (40 mg and 5 mg). Comparative bioavailability was assessed through adjusted geometric mean ratios for exposure parameters (maximum observed plasma concentration C max , area under plasma concentration-time curve to last measurable concentration AUC last and extrapolated to infinity AUC 0–inf ), with a prespecified bioequivalence range of 0.80 to 1.25. Secondary endpoints included partial AUCs and safety assessments. The study population ( N = 45) was predominantly male (88.9%) and White (55.6%), with mean age of 29.6 ± 8.01 years. Adjusted geometric mean ratios comparing the primary exposure parameters ( C max , AUC last , and AUC 0–inf ) for CTx-1301 versus d-MPH XR were within the bioequivalence range (0.80–1.25) at both the high and low doses. The CTx-1301-to-d-MPH XR partial AUC ratios were within the bioequivalence range from 0 to 9 hours post-dose. At later intervals (AUC 9–12 and AUC 12–16 ), adjusted geometric mean ratios exceeded the upper bioequivalence threshold, consistent with the expected contribution of the third medication release component. Dose proportionality was observed between the two CTx-1301 doses and two d-MPH XR formulations. CTx-1301 was generally well tolerated. The most commonly reported adverse events included tachycardia, insomnia, headache, nausea, and euphoric mood. The incidence of treatment-emergent adverse events was numerically lower with CTx-1301 than with d-MPH XR; however, no statistical analysis was performed. Key exposure parameters including C max , AUC last , and AUC 0–inf for trimodal CTx-1301 were statistically bioequivalent to bimodal d-MPH XR. Interval‑specific PK analyses demonstrated higher exposure with CTx‑1301 during later post-dose intervals (9–16 h), consistent with the formulation’s third release component. However, the clinical relevance of these PK differences requires further evaluation. CTx-1301 demonstrated dose proportionality and was well tolerated at high and low doses. Registration: ClinicalTrials.gov, NCT04138498; 19 September 2019.