Prescribing Notes

ADHD, narcolepsy

In children, hyperkinesia or attention deficit hyperactivity disorder (ADHD) is characterised by inattention, overactivity and impulsiveness. Drug therapy should only be used for those who fail to respond to psychotherapy, and only as part of a comprehensive treatment programme.

Given chronically in low doses, CNS stimulants such as dexamfetamine, lisdexamfetamine and methylphenidate improve symptoms of ADHD within four to eight weeks. Those patients who respond typically require long-term medication up to 10 years of age. Therapy should be withdrawn gradually once a year to determine if it is still necessary. Tolerance and dependence may develop and treatment should be withdrawn gradually to avoid extreme fatigue and depression. Dexamfetamine may also be useful in narcolepsy but growth retardation and mood disturbance can occur. Lisdexamfetamine is a prodrug that is converted in the blood to dexamfetamine. It is available as a separate product for use in adults who have had ADHD symptoms in childhood. Methylphenidate causes fewer side effects and is usually the drug of first choice in ADHD. In epileptic children it may increase seizure frequency, making dexamfetamine preferable.

Atomoxetine is not a CNS stimulant, nor is it an amfetamine derivative, but it has been shown to reduce the signs and symptoms of ADHD in children. It can also be initiated in adults with ADHD provided that the presence of symptoms in childhood can be confirmed.

Guanfacine, a non-stimulant centrally acting antiadrenergic agent, can be used in children and adolescents who have had an inadequate response to stimulants or for whom stimulants are unsuitable or not tolerated.

Modafinil and pitolisant are selective, non-amfetamine wake-promoting agents. They reduce excessive daytime sleepiness seen in narcolepsy without inducing anxiety, palpitations and hyperkinesia commonly caused by CNS stimulants.

Sodium oxybate is a CNS depressant which reduces excessive daytime sleepiness and cataplexy in patients with narcolepsy.