Cardiovascular effects: Domperidone has been associated with prolongation of the QT interval on the electrocardiogram. During post-marketing surveillance, there have been very rare cases of QT-prolongation and torsades de pointes in patients taking domperidone. These reports included patients with confounding risk factors, electrolyte abnormalities and concomitant treatment which may have been contributing factors (see Adverse Reactions).
Epidemiological studies showed that domperidone was associated with an increased risk of serious ventricular arrhythmias or sudden cardiac death (see Adverse Reactions). A higher risk was observed in patients older than 60 years, patients taking daily doses greater than 30 mg, and patients concurrently taking QT-prolonging drugs or CYP3A4 inhibitors.
Domperidone should be used at the lowest effective dose in adults and children.
Domperidone is contraindicated in patients with known existing prolongation of cardiac conduction intervals, particularly QTc, in patients with significant electrolyte disturbances (hypokalaemia, hyperkalaemia, hypomagnesaemia), or bradycardia, or in patients with underlying cardiac diseases such as congestive heart failure due to increased risk of ventricular arrhythmia (see Contraindications).
Electrolyte disturbances (hypokalaemia, hyperkalaemia, hypomagnesaemia) or bradycardia are known to be conditions increasing the proarrhythmic risk.
Treatment with domperidone should be stopped if signs or symptoms occur that may be associated with cardiac arrhythmia, and the patients should consult their physician.
Patients should be advised to promptly report any cardiac symptoms.
Drug interaction potential: The main metabolic pathway of domperidone is through CYP3A4. In vitro and human data show that the concomitant use of drugs that significantly inhibit this enzyme may result in increased plasma levels of domperidone. Co-administration of domperidone with potent CYP3A4 inhibitors which have been shown to cause QT interval prolongation is contraindicated (see Contraindications).
Caution should be exercised when domperidone is co-administered with potent CYP3A4 inhibitors which have not been shown to cause QT interval prolongation such as indinavir and patients should be monitored closely for signs or symptoms of adverse reactions (see Adverse Reactions).
Caution should be exercised when domperidone is co-administered with drugs which have been shown to cause QT interval prolongation and patients should be monitored closely for signs or symptoms of cardiovascular adverse reactions (see Adverse Reactions). Examples include: anti-arrhythmics class IA (e.g., disopyramide, quinidine);
anti-arrhythmics class III (e.g., amiodarone, dofetilide, dronedarone, ibutilide, sotalol);
certain antipsychotics (e.g., haloperidol, pimozide, sertindole);
certain antidepressants (e.g., citalopram, escitalopram);
certain antibiotics (e.g., levofloxacin, moxifloxacin);
certain antifungal agents (e.g., pentamidine);
certain antimalarial agents (e.g., halofantrine);
certain gastro-intestinal drugs (e.g., dolasetron);
certain drugs used in cancer (e.g., toremifene, vandetanib);
certain other drugs (e.g., bepridil, methadone).
Antacids or antisecretory agents should not be taken simultaneously with oral formulations of MOTILIUM, as they lower the oral bioavailability of domperidone. When used concomitantly, MOTILIUM should be taken before meals and antacids or antisecretory agents after meals.
Excipients: The film-coated tablets contain lactose and may be unsuitable for patients with lactose intolerance, galactosemia or glucose/galactose malabsorption.
The oral suspension contains sorbitol and may be unsuitable for patients with sorbitol intolerance.
Effects on Ability to Drive and Use Machines: Dizziness and somnolence have been observed following use of domperidone (see Adverse Reactions). Therefore, patients should be advised not to drive or use machinery or engage in other activities requiring mental alertness and coordination until they have established how MOTILIUM affects them.