Pharmacokinetics and Exposure-Response Relationships of Dasotraline in the Treatment of Attention-Deficit/Hyperactivity Disorder in Adults

BACKGROUND AND OBJECTIVES: Dasotraline is a novel inhibitor of dopamine and norepinephrine reuptake currently being investigated in clinical studies for the treatment of attention-deficit/hyperactivity disorder (ADHD). Uniquely, relative to current ADHD medications, dasotraline has a slow absorption and long elimination half-life. Here we relate the pharmacokinetics and pharmacodynamics of dasotraline to reduction in ADHD symptoms based on simulated clinical trial outcomes. METHODS: Dasotraline pharmacokinetics were analyzed by population pharmacokinetic methodologies using data collected from 395 subjects after single or multiple oral dose administrations ranging from 0.2 to 36 mg (three phase I studies and one phase II ADHD study). Population pharmacokinetic and pharmacodynamic models related individual dasotraline exposures to norepinephrine metabolite 3,4-dihydroxyphenylglycol (DHPG) concentrations, ADHD symptoms, and study discontinuation (probability of dropout). RESULTS: Dasotraline pharmacokinetics were described by a one-compartment model with dual (linear plus nonlinear) elimination. In an ADHD population treated with dasotraline 4 or 8 mg/day, dasotraline was characterized by a mean apparent half-life of 47 h and plasma concentrations reached steady-state by 10 days of dosing. A population pharmacokinetic and pharmacodynamic model of DHPG indicated clinically significant norepinephrine transporter inhibition was achieved as a function of time-matched dasotraline concentrations. Dasotraline exposure reduced ADHD symptoms in a sigmoid E(max) time-course model. Clinical trial simulations described the effects of dose, duration, and sample size on clinical outcomes. CONCLUSION: These results related dasotraline pharmacokinetics to pharmacological activity in ADHD, and support the novel concept that maintaining constant, steady-state dopamine and norepinephrine reuptake inhibition throughout a 24-h dosing interval is a novel pharmacological approach to the management of ADHD symptoms. Clinicaltrials.gov identifier: NCT01692782. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s40261-015-0358-7) contains supplementary material, which is available to authorized users.