A Pilot Evaluation of the Safety, Tolerability, Pharmacokinetics, and Effectiveness of Memantine in Pediatric Patients with Attention-Deficit/Hyperactivity Disorder Combined Type

Abstract

Disturbances in N-methyl-D-aspartate (NMDA) receptor activity may play a role in attention-deficit/hyperactivity disorder (ADHD). This study is a preliminary evaluation of the safety, pharmacokinetics, and effectiveness of the NMDA receptor antagonist memantine in pediatric ADHD. An open-label, dose-finding, 8-week, trial in outpatients 6-12 years old with ADHD combined type. Memantine oral solution (2 mg/mL) was titrated to 10 mg/day (n = 8) or 20 mg/day (n = 8). Safety data and blood samples for pharmacokinetic analyses were collected. The ADHD Rating Scale-IV (ADHD-IV) and Clinical Global Impression of Severity (CGI-S) scale measured the effectiveness of memantine. There were no discontinuations due to adverse events (AEs), serious AEs, deaths, or suicides. Most AEs were mild and occurred during the first week of treatment. The 20 mg/day memantine dose was associated with a higher rate of completion and larger mean improvement on the ADHD-IV and CGI-S than 10 mg/day memantine. Pharmacokinetic analyses suggest response to memantine may be dose-dependent beyond an initial threshold concentration. This pilot study suggests that a memantine dose of 20 mg/day may be a safe and possibly effective treatment for pediatric ADHD. Further investigations of memantine in ADHD appear to be warranted.