Prescribing of drugs for attention-deficit hyperactivity disorder in opioid maintenance treatment patients in Norway.

BACKGROUND Attention-deficit hyperactivity disorder (ADHD) is a risk factor for the development of substance use disorders. Treatment of ADHD with psychostimulants in patients on opioid maintenance treatment (OMT) has been restricted in Norway. We examined the use of prescribed drugs for ADHD in OMT patients and assessed co-medication with other psychotropics. METHODS Data were drawn from the nationwide Norwegian Prescription Database (NorPD), which includes all prescriptions filled at pharmacies. The study population included subjects ≥18 years on OMT during 2008-2010. RESULTS In 2010, 6,116 patients received OMT and 2.8% of these also received ADHD drugs. This percentage is seven times greater than that in the gender- and age-specific general population of Norway. The prevalence was higher in the youngest patients, while there was no gender difference. Methylphenidate was the most commonly used drug for ADHD in OMT patients, followed by atomoxetine. 60% of OMT patients filled at least one prescription for antidepressants, anxiolytics or hypnotics, and percentages were similar for users and non-users of ADHD drugs. CONCLUSION Treatment with ADHD drugs was higher in OMT patients than expected from the general population, but was relatively low compared to the prevalence of ADHD in patients with substance use disorders reported in the literature.