A 29-year-old woman comes to her primary care physician for a routine examination. Her past medical history is significant for narcolepsy, which is being treated by a neurologist. Which of the following medications is most likely to reduce excessive daytime sleepiness in this patient?

A. Atomoxetine
B. Desmopressin
C. Imipramine
D. Lorazepam
E. Modafinil

The correct answer is E. Narcolepsy is a genetically based disorder that involves the derangement of rapid eye movement sleep and sleep-wake control and results in the sudden onset of sleep with or without cataplexy (sudden collapse while awake). Stimulants (eg, amphetamines and methylphenidate) have been used with success but involve side effects. More recently, the advent of modafinil (Provigil) has increased the options for treatment of excessive daytime sleepiness in these patients. Although its mechanism has not been fully elucidated, it seems to possess a safer adverse effects profile than stimulants.

Answer A is not correct. Atomoxetine (Strattera) is a selective norepinephrine reuptake inhibitor that has shown greater efficacy than placebo in treating attention-deficit/hyperactivity disorder in adults. It has not been used or evaluated in the treatment of narcolepsy.

Answer B is not correct. Desmopressin is a synthetic vasopressin analog that is used to decrease urine output by retaining water and concentrating urine in the distal tubules. With respect to sleep disorders, it is used in the treatment of enuresis but not narcolepsy.

Answer C is not correct. Tricyclic antidepressants (TCAs) such as imipramine have been used as treatments for cataplexy and sleep paralysis in narcoleptic patients. However, TCAs are not first-line therapy for excessive daytime sleepiness.

Answer D is not correct. Lorazepam is an intermediate-acting benzodiazepine used in the treatment of panic attacks and anxiety. It would increase daytime sleepiness in a patient with narcolepsy.

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