Domperidone is a dopamine antagonist with anti-emetic properties, Domperidone does not readily cross the blood-brain barrier. In domperidone users, especially in adults, extrapyramidal side effects are very rare, but domperidone promotes the release of prolactin from the pituitary. Its anti-emetic effect may be due to a combination of peripheral (gastrokinetic) effects and antagonism of dopamine receptors in the chemoreceptor trigger zone, which lies outside the blood-brain barrier in the area postrema. Animal studies, together with the low concentrations found in the brain, indicate a predominantly peripheral effect of domperidone on dopamine receptors.
INDICATIONS

• Nausea
• Vomiting

Pharmacokinetic Properties:
Absorption: Domperidone is rapidly absorbed after oral administration, with peak plasma concentrations occurring at approximately 1 hr after dosing.
Distribution: Oral domperidone does not appear to accumulate or induce its own metabolism; a peak plasma level after 90 minutes of 21 ng/ml atter two weeks oral administration of 30 mg per day was almost the same as that of 18 ng/ml after the first dose.
Biotransformation: Domperidone undergoes rapid and extensive hepatic metabolism by hydroxylation and N-dealkylation.
Excretion: Urinary and faecal excretions amount to 31 and 66% of the oral dose respectively. The plasma half-life after a single oral dose is 7-9 hours in healthy subjects but is prolonged in patients with severe renal insufficiency
Dosage form :Syrup base Suspension
Dosage And Administrations: Domperidone should be used at the lowest effective dose for the shortest duration necessary to control nausea and vomiting. Patients should try to take each dose at the scheduled time. If a scheduled dose is missed, the missed dose should be omitted and the usual dosing schedule resumed. The dose should not be doubled to make up for a missed dose.
Usually, the maximum treatment duration should not exceed one week. Adults and adolescents (12 years of age and older and weighing 35 kg or more)
10 ml (of oral suspension containing domperidone 1 mg per ml) up to three times per day with a maximum daily dose of 30 ml per day.
Oral domperidone should be taken before meals/feeding. If taken after meals absorption of the drug is somewhat delayed.
Hepatic Impairment Domperidone is contraindicated in moderate or severe hepatic impairment. Dose modification in mild hepatic impairment is however not needed. Renal Impairment
Since the elimination half-life of domperidone is prolonged in severe renal impairment, on repeated administration, the dosing frequency of domperidone should be reduced to once or twice daily depending on the severity of the impairment, and the dose may need to be reduced.Such patients on prolonged therapy should be reviewed regularly.
Contraindications:
Domperidone is contraindicated in the following situations:

• Known hypersensitivity to domperidone.
• Prolactin-releasing pituitary tumour (prolactinoma).
• When stimulation of the gastric motility could be harmful, e.g in patients with gastro-intestinal haemorrhage, mechanical obstruction or perforation.
• In patients with moderate or severe hepatic impairment. in patients who have known existing prolongation of cardiac conduction intervals, particularly QTc, patients with significant electrolyte disturbances or underlying cardiac diseases such as congestive heart failure
• Co-administration with QT-prolonging drugs, át the exception of apomorphine
• Co-administration with potent CYP3A4 inhibitors (regardless of their QT prolonging effects)

Side effects:

• Breast pain
• Diarrhea
• Dry mouth
• Headache
• Migraine
• Nausea
• Rash
• Breast milk flowing from the nipple
• Fast, pounding, or racing heartbeat or pulse
• Menstrual irregularities
• Swelling of the breast (males)
• Dizziness or fainting
• Irregular heart beat
• Signs of an allergic reaction (such as difficulty breathing, hives, swelling of the face or throat)

Pregnancy: Domperidone should only be used during pregnancy when justified by the anticipated therapeutic benefit.
Breast-feeding: Domperidone is excreted in human milk and breast-fed infants receive less than 0.1% of the maternal weight-adjusted dose. Occurrence of adverse effects, in particular cardiac effects cannot be excluded after exposure via breast milk. A decision should be made whether to discontinue breast-feeding or to discontinue/abstain from domperidone therapy taking into account the benefit of breast feeding for the child and the benefit of therapy for the woman. Caution should be exercised in case of QTc prolongation risk factors in breast-fed infants.