Overview
Domperidone is a dopamine antagonist with antiemetic properties, primarily used to relieve nausea and vomiting. Unlike some other antiemetics, it does not readily cross the blood-brain barrier, reducing the risk of central nervous system side effects.

Mechanism of Action
It blocks dopamine D2 receptors in the chemoreceptor trigger zone, located outside the blood-brain barrier, which helps prevent nausea and vomiting. It also increases lower esophageal sphincter pressure and upper gastrointestinal motility.

Dosage and Administration
For adults, the typical dose is 10 mg up to three times a day, taken before meals. It should be used at the lowest effective dose for the shortest possible duration.

Side Effects
Generally well-tolerated, but can cause dry mouth. A rare but serious risk is QT prolongation and cardiac arrhythmias, especially at high doses or in older adults.

Contraindications
Contraindicated in patients with moderate to severe hepatic impairment, known existing prolongation of cardiac conduction intervals, underlying cardiac diseases, or those receiving potent CYP3A4 inhibitors.

Pregnancy and Lactation
Should only be used during pregnancy when justified by the anticipated therapeutic benefit. It is excreted in breast milk in small amounts; use in breastfeeding is generally not recommended unless clearly necessary.