1. Clinical Overview
A fixed-dose combination (FDC) of an antispasmodic (Dicyclomine) and an H2-receptor antagonist (Ranitidine). Dicyclomine relieves smooth muscle spasm in the gastrointestinal tract, while Ranitidine reduces gastric acid secretion. This combination is primarily used for the symptomatic relief of acid-related disorders accompanied by visceral colic and spasms. Note: The FDC of Dicyclomine and Ranitidine was banned by the Indian government in 2018 under Gazette Notification G.S.R. 72(E) due to an unfavorable risk-benefit ratio. However, individual components are still available separately and the combination may be found in some contexts, though its prescription is strongly discouraged.
| Onset | Duration | Bioavailability |
|---|---|---|
| Dicyclomine: 1-2 hours (oral). Ranitidine: Within 1 hour (oral). | Dicyclomine: 4-6 hours. Ranitidine: 8-12 hours. | Dicyclomine: ~67-73% (oral). Ranitidine: 50-60% (oral, subject to first-pass metabolism). |
2. Mechanism of Action
Dicyclomine exerts a direct relaxant effect on visceral smooth muscle and possesses antimuscarinic (anticholinergic) activity, relieving colic and spasms. Ranitidine competitively inhibits histamine at H2 receptors of gastric parietal cells, leading to a marked reduction in basal and stimulated gastric acid secretion, volume, and hydrogen ion concentration.
3. Indications & Uses
- Symptomatic relief of abdominal colic and spasms associated with functional gastrointestinal disorders (e.g., Irritable Bowel Syndrome) with concomitant acid-peptic disease. (Note: This was the intended use prior to ban; current use is not recommended.)
4. Dosage & Administration
Adult Dosage: One tablet (Dicyclomine 10mg + Ranitidine 150mg) twice daily, preferably before meals or at bedtime. Maximum: Two tablets per day. Note: This is historical data; the combination is banned.
Administration: Take orally with a glass of water. Can be taken before food or at bedtime. Do not crush or chew unless advised. Avoid concomitant antacids within 1-2 hours of Ranitidine dose as they may impair absorption.
5. Side Effects
Common side effects may include:
- Dry mouth
- Constipation
- Blurred vision
- Dizziness
- Drowsiness
- Headache
- Nausea
- Diarrhea (paradoxical)
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Antacids (Aluminum/Magnesium hydroxide) | Decreased absorption of Ranitidine | Moderate |
| Ketoconazole, Itraconazole | Decreased absorption of azole antifungals due to increased gastric pH | Major |
| Digoxin | Increased bioavailability of Digoxin (theoretical) | Moderate |
| Warfarin | Potential increased anticoagulant effect (rare, disputed) | Moderate |
| Metoprolol, Propranolol | Increased plasma levels of beta-blockers due to reduced hepatic blood flow (Ranitidine) | Moderate |
| Midazolam, Triazolam | Increased sedation and prolonged effect (CYP3A4 inhibition by Ranitidine is weak) | Moderate |
| Other Anticholinergics (e.g., Amitriptyline, Atropine) | Additive anticholinergic side effects | Major |
| Alcohol | Enhanced sedative effect with Dicyclomine | Moderate |
| Metformin | Increased Metformin exposure (reduced renal clearance by Ranitidine) | Moderate |
| Phenytoin | Increased Phenytoin levels (Ranitidine inhibits metabolism) | Major |
7. Patient Counselling
- Do take the medicine as prescribed, before meals or at bedtime.
- Do inform your doctor about all other medicines you are taking.
- Do maintain adequate fluid intake to avoid constipation.
- Don't crush or chew the tablet unless instructed.
- Don't take antacids within 1-2 hours of this medicine.
- Don't stop taking abruptly if used for ulcer treatment.
- Don't use in pregnancy or breastfeeding without medical advice.
8. Toxicology & Storage
Overdose: Dicyclomine: CNS effects (restlessness, psychosis, seizures, respiratory failure), anticholinergic crisis (hyperthermia, hot dry skin, blurred vision, tachycardia, urinary retention, ileus). Ranitidine: Bradycardia, hypotension, arrhythmias, seizures, renal failure.
Storage: Store below 30°C in a cool, dry place. Protect from light and moisture. Keep out of reach of children.