Pitolisant

• Narcolepsy
• Excessive Daytime Sleepiness
• Sleep Disorders

Pitolisant is a first-in-class histamine H3 receptor antagonist/inverse agonist used to treat excessive daytime sleepiness in patients with narcolepsy. By enhancing histamine neurotransmission, it offers a unique mechanism distinct from traditional stimulants.

Mechanism of Action

Pitolisant works through the histaminergic system:

• H3 receptor antagonist/inverse agonist: Blocks presynaptic H3 autoreceptors
• Increases histamine release: H3 blockade disinhibits histamine neurons in the tuberomammillary nucleus
• Enhances wakefulness: Histamine promotes arousal through hypothalamic wake-promoting circuits
• Modulates other neurotransmitters: Also affects norepinephrine, dopamine, and acetylcholine release

Unlike amphetamines, pitolisant does not directly stimulate catecholamine release.

Available Formulations

Pitolisant is available as oral tablets:

• 4.45 mg tablets
• 17.8 mg tablets

Tablets should be taken once daily upon wakening.

Medical Uses

FDA-Approved Indications:

• Excessive daytime sleepiness in adult patients with narcolepsy

Pitolisant is not a controlled substance, unlike traditional wake-promoting agents.

Dosing Guidelines

Adults:

• Week 1: 8.9 mg (two 4.45 mg tablets) once daily
• Week 2: 17.8 mg once daily
• Week 3: May increase to maximum 35.6 mg once daily

Titration:

• Increase weekly based on response and tolerability
• Maximum: 35.6 mg once daily

Timing:

• Take upon awakening in the morning
• Avoid late-day dosing to prevent insomnia

Important Safety Information

Contraindications:

• Severe hepatic impairment (Child-Pugh C)

Warnings and Precautions:

• QT prolongation: Avoid in patients with known QT prolongation, history of cardiac arrhythmias, or taking other QT-prolonging medications
• Psychiatric symptoms: Monitor for insomnia, anxiety, irritability, and potential worsening of psychiatric conditions
• Reduced effectiveness of hormonal contraceptives: Use alternative or additional contraception

Pregnancy:

• Limited data; use only if benefit outweighs risk
• May reduce effectiveness of hormonal contraceptives (use non-hormonal methods)

Drug Interactions

CYP2D6 Substrates:

• Pitolisant is a weak CYP2D6 inducer
• May reduce efficacy of CYP2D6 substrates (some antidepressants, antipsychotics)

Strong CYP3A4 Inducers (rifampin, phenytoin):

• May reduce pitolisant exposure

Strong CYP2D6 Inhibitors (fluoxetine, paroxetine, quinidine):

• May increase pitolisant exposure; max 17.8 mg/day

QT-Prolonging Drugs:

• Avoid combination due to additive QT risk

Oral Contraceptives:

• Pitolisant may reduce efficacy; use alternative contraception

Antihistamines (H1 antagonists):

• May reduce pitolisant efficacy

Special Populations

• Hepatic Impairment:
  • Moderate (Child-Pugh B): Max 17.8 mg daily
  • Severe (Child-Pugh C): Contraindicated
• Renal Impairment:
  • ESRD or severe impairment: Max 17.8 mg daily
• Elderly: No specific adjustment; use with caution
• Pregnancy: Avoid hormonal contraceptives; limited data on fetal effects