Objectives: To compare the effects of metadoxine extended release (ER) with those of placebo on inattentive (IA) versus hyperactive-impulsive (H-I) symptoms and predominantly inattentive (PI) versus combined type (CT) subtype in adults with attention-deficit/hyperactivity disorder (ADHD).
Methods: This was a 1:1 randomized, double-blind, parallel-design study of metadoxine ER 1400 mg/day for 6 weeks in 120 adults with ADHD. Efficacy measures were baseline to end-of-treatment changes in Conners' Adult ADHD Rating Scale-Investigator Rated (CAARS-INV) Total ADHD Symptoms scores with adult ADHD prompts, the Test of Variables of Attention ADHD scores, and response rates (≥ 25% or ≥ 40% improvement in CAARS-INV Total ADHD Symptoms score).
Results: There was a significant decrease in CAARS-INV Total ADHD Symptoms scores in patients with ADHD-PI taking metadoxine ER (40%) compared with those taking placebo (21%) (P < 0.05), while the decrease for patients with ADHD-CT was not significant (27% vs 26%). Similarly, there was a significant decrease in IA scores in patients with ADHD-PI (metadoxine ER, 50% vs placebo, 23%; P < 0.005), while the change in patients with ADHD-CT was not significant. There was no significant difference in percent decreases seen in H-I scores for patients with PI or ADHD-CT. Significantly higher response rates at both cutoffs (ie, 25% and 45% improvement) were seen in the metadoxine ER group compared with the placebo group in CAARS-INV Total ADHD Symptoms scores in patients with ADHD-PI, but not those with ADHD-CT. Test of Variables of Attention ADHD scores were significantly decreased in the metadoxine ER group compared with the placebo group for patients with ADHD-PI, but not those with ADHD-CT.
Conclusion: These data suggest that metadoxine ER is selectively efficacious for treating IA symptoms in adults with ADHD-PI.
Trial registration: www.ClinicalTrials.gov identifier NCT01243242.