Usage
Domperidone + Ranitidine is a combination medication primarily used to treat gastrointestinal disorders where delayed gastric emptying and excess stomach acid are contributing factors. Conditions this drug is prescribed for include:
- Gastroesophageal reflux disease (GERD)
- Dyspepsia (indigestion)
- Nausea and vomiting associated with gastroparesis
- Zollinger-Ellison syndrome (a rare condition causing excessive stomach acid production)
It’s pharmacological classification includes a prokinetic agent (domperidone) and a histamine H2-receptor antagonist (ranitidine).
Domperidone increases the movement of the stomach and intestines, speeding up gastric emptying. Ranitidine decreases stomach acid production.
Alternate Names
While “Domperidone + Ranitidine” is the generic name, brand names vary depending on the manufacturer and region. One example is Rantac DOM. Motilium is an alternate name for Domperidone.
How It Works
Domperidone:
- Pharmacodynamics: Domperidone is a dopamine D2 receptor antagonist in the chemoreceptor trigger zone (CTZ), located outside the blood-brain barrier. It also acts as a peripheral dopamine D2-receptor antagonist in the upper gastrointestinal tract, enhancing gastric motility and accelerating gastric emptying.
- Pharmacokinetics: Domperidone is rapidly absorbed after oral administration. It undergoes hepatic metabolism primarily via CYP3A4. The drug is excreted in both urine and feces.
Ranitidine:
- Pharmacodynamics: Ranitidine competitively inhibits the action of histamine at H2 receptors of the parietal cells in the stomach, reducing basal and stimulated gastric acid secretion.
- Pharmacokinetics: Ranitidine is absorbed after oral administration, with peak plasma concentrations reached in about 2 hours. It is partially metabolized in the liver. Excretion is primarily renal.
The combination of domperidone and ranitidine provides synergistic relief by addressing both gastric motility and acid secretion.
Dosage
Standard Dosage
Adults:
The standard dose is one tablet of Domperidone 10mg + Ranitidine 150mg, taken three times a day, preferably 15-30 minutes before meals. In some cases, the dose may be increased to 20mg of Domperidone and 300 mg of Ranitidine, taken twice a day, or as prescribed by the physician.
Children:
Domperidone + Ranitidine is generally not recommended for children. If used, the dose should be calculated based on the child’s weight (1.2-2.4 mg/kg/day of domperidone and 2-4 mg/kg/day of ranitidine), divided into three or four doses. Pediatric use requires careful consideration of potential cardiac risks associated with domperidone.
Special Cases:
- Elderly Patients: Dosage adjustment may be necessary. Start with a lower dose and monitor for side effects.
- Patients with Renal Impairment: Reduce the dose of both drugs based on creatinine clearance.
- Patients with Hepatic Dysfunction: Reduce the dose, particularly for domperidone.
- Patients with Comorbid Conditions: Carefully assess potential drug interactions, especially in patients with cardiovascular disease.
Clinical Use Cases
Domperidone + Ranitidine is not typically used in clinical settings like intubation, surgical procedures, mechanical ventilation, or emergency situations.
Dosage Adjustments
Dosage adjustments are based on individual patient characteristics, including renal and hepatic function, comorbid conditions, and concomitant medications.
Side Effects
Common Side Effects:
- Headache
- Diarrhea or constipation
- Dry mouth
- Dizziness
- Drowsiness
Rare but Serious Side Effects:
- Cardiac arrhythmias (QT prolongation)
- Extrapyramidal symptoms (movement disorders)
- Gynecomastia (breast enlargement in males)
- Galactorrhea (milk production)
Long-Term Effects:
Long-term use of this combination, especially domperidone, should be avoided due to the potential for cardiac side effects.
Adverse Drug Reactions (ADR):
Any signs of cardiac arrhythmia, extrapyramidal symptoms, or hypersensitivity reactions should prompt immediate discontinuation and medical intervention.
Contraindications
- Hypersensitivity to domperidone or ranitidine.
- Gastrointestinal hemorrhage or obstruction.
- Prolactinoma (a pituitary tumor).
- Concomitant use of strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole).
- Patients with long QT syndrome or other cardiac conduction abnormalities.
Drug Interactions
- Ketoconazole, itraconazole, and other strong CYP3A4 inhibitors increase domperidone levels.
- Antacids may reduce the absorption of ranitidine.
- Drugs that prolong the QT interval (e.g., some antiarrhythmics, macrolides) may increase the risk of arrhythmias.
Pregnancy and Breastfeeding
Domperidone is excreted in breast milk. Its use during breastfeeding should be carefully considered. Ranitidine’s safety during pregnancy and breastfeeding has not been fully established.
Drug Profile Summary
- Mechanism of Action: Domperidone: Dopamine D2 receptor antagonist; Ranitidine: H2 receptor antagonist.
- Side Effects: See sections above.
- Contraindications: See section above.
- Drug Interactions: See section above.
- Pregnancy & Breastfeeding: Use with caution.
- Dosage: See section above.
- Monitoring Parameters: ECG (for QT prolongation), liver function tests, renal function tests.
Popular Combinations
This combination itself is used clinically.
Precautions
See contraindications and drug interactions sections. Assess cardiac, renal, and hepatic function before initiating therapy. Exercise caution in elderly patients.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Domperidone + Ranitidine?
A: See the dosage section above.
Q2: What are the most serious side effects?
A: Cardiac arrhythmias (QT prolongation) and extrapyramidal symptoms.
Q3: Can this medication be used during pregnancy?
A: Use with caution during pregnancy and breastfeeding. Consult a specialist if necessary.
Q4: What are the contraindications to using this drug?
A: See the contraindications section above.
Q5: How does this medication interact with other drugs?
A: See drug interactions section above.
Q6: What should be monitored in patients taking this combination?
A: ECG (for QT prolongation), liver and renal function tests.
Q7: Can this combination be used in children?
A: It is generally not recommended for children. Use with extreme caution if necessary, after careful assessment of the benefit-risk ratio.
Q8: What are the long-term effects of this medication?
A: Long-term use, especially of domperidone, should be avoided due to potential cardiac risks.
Q9: What are the alternatives to this medication?
A: Alternatives depend on the specific indication. Other prokinetics (e.g., metoclopramide) or proton pump inhibitors (e.g., omeprazole) may be considered. Discuss options with the patient’s physician.
