**Question:** Pitolisant is approved for treatment of

A. Narcolepsy
B. Hypersomnia
C. Delirium
D. Alzheimer's disease

**Correct Answer:** **A. Narcolepsy**

**Core Concept:** Narcolepsy is a chronic neurological disorder characterized by excessive daytime sleepiness, sudden urges to sleep, sleep paralysis, and cataplexy. It is caused by a deficiency in orexin (hypocretin) neurotransmitters in the brainstem that regulate sleep-wake cycle.

**Why the Correct Answer is Right:** Pitolisant is a wakefulness-promoting agent that acts as a selective and potent agonist of the histamine H3 receptor. By enhancing histamine neurotransmission, it increases arousal and reduces excessive daytime sleepiness in patients with narcolepsy.

**Why Each Wrong Option is Incorrect:**

**Option B (Hypersomnia):** Hypersomnia refers to excessive sleepiness or excessive daytime sleepiness without the presence of specific sleep disorders. Pitolisant is primarily used for narcolepsy, not hypersomnia.

**Option C (Delirium):** Delirium is a transient disturbance in cognition and attention, often seen in critically ill patients or due to medication side effects, but it is not a primary indication for Pitolisant use.

**Option D (Alzheimer's disease):** Alzheimer's disease is a progressive neurodegenerative disorder characterized by memory loss, cognitive decline, and dementia. Pitolisant is not approved for treating Alzheimer's disease.

**Clinical Pearl:** Narcolepsy is a unique sleep disorder that can significantly impact a patient's daily functioning. It is essential for physicians to diagnose and initiate appropriate treatment like Pitolisant to improve patient quality of life and reduce the risk of accidents due to excessive sleepiness.