An 8-week, randomized controlled trial of atomoxetine, atomoxetine plus buspirone, or placebo in adults with ADHD.

Objective: To examine the efficacy and safety of atomoxetine combined with buspirone versus atomoxetine monotherapy and placebo in adult attention-deficit/hyperactivity disorder (ADHD).
Method: In this randomized, 8-week, 3-arm, double-blind, placebo-controlled trial conducted from November 2004 through December 2005, 241 adults with ADHD were randomly assigned in a 2:2:1 ratio to receive up to twice-daily atomoxetine and thrice-daily buspirone (n = 97), twice-daily atomoxetine (n = 97), or placebo (n = 47). Participants met the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision criteria for ADHD. The primary efficacy measure was the adult ADHD Investigator Symptom Rating Scale (AISRS).
Results: Decrease in the AISRS total score was significantly greater for atomoxetine-buspirone than placebo at all time points from weeks 1 to 7, with an estimated mean difference of -4.80 (P = .001). Reduction in the mean AISRS total score was numerically greater for atomoxetine-buspirone than for atomoxetine at all time points, but statistically significant at week 4 only (estimated difference = -2.04, P < .10). The effect size for atomoxetine plus buspirone was 0.51, and for atomoxetine alone, it was 0.40. Insomnia, nausea, dry mouth, headache, and asthenia were frequently reported adverse events for both active treatment groups, and dizziness was also frequently reported for the atomoxetine-buspirone group. Discontinuations due to treatment-related adverse effects were 15.5% for atomoxetine-buspirone, 11.3% for atomoxetine, and 14.9% for placebo.
Conclusions: There was little indication of improvement for atomoxetine plus buspirone versus atomoxetine monotherapy, as most efficacy measures showed only slightly greater quantitative improvement for the combination, generally without statistical significance. It is of note, however, that the quantitative differences between these 2 groups were virtually all in the direction of greater efficacy for the atomoxetine plus buspirone group.
Trial Registration: clinicaltrials.gov Identifier: NCT00174226.
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