522. Efficacy of mirtazapine in stimulant associated insomnia in patients with ADHD

Abstract

Stimulants are the most commonly prescribed medications for Attention Deficit Hyperactivity Disorder (ADHD). One major side effect of these medications can be an exacerbation or induction of insomnia. ADHD children have been reported as having higher rates of insomnia as compared to psychiatric and pediatric controls; the insomnia was substantially exacerbated by stimulant therapy (Stein MA 1999). Approved hypnotics have not been well studied in stimulant-associated insomnia (SAI). Mirtazapine is a recently marketed antidepressant, which can be mildly sedating in the lower range of therapeutic doses. We now present the findings of an open trial of mirtazapine in ADHD patients with SAI. Sixteen patients with early insomnia and ADHD, who were receiving stimulants, were offered four to six weeks of open clinical treatment with mirtazapine (starting dose: 3.75–7.5 mg qHS, final daily dose: 3.75–45 mg/day, mean: 9.41 ± 10.8 SD mg/day). Two patients developed significant daytime sedation on the first day of treatment and therefore their results are not included. Patients ranged in age from 12 to 47 years of age (mean: 29.8 years). All patients were receiving stable doses of stimulants and met both DSM-IV and childhood K-SADS (self or parent report) criteria for ADHD. Sleep patterns were assessed by self-report of average number of hours slept nightly over the past week, at baseline and then during mirtazapine treatment. Mirtazapine was well tolerated by the remaining fourteen patients. Sleep was improved in all patients (mean hours of sleep: baseline 5.3 ± 1.2; after mirtazapine: 7.9 ± 0.6; t (13) = 11.7, p < 0.0001). All patients elected to continue mirtazapine treatment at the completion of the trial. Mirtazapine significantly improved SAI in this open, pilot trial.