1. Clinical Overview
A fixed-dose combination of an antispasmodic agent (Dicyclomine) and an antiflatulent agent (Simethicone). Dicyclomine is an anticholinergic that relieves smooth muscle spasm in the gastrointestinal tract, while Simethicone is a surfactant that reduces surface tension of gas bubbles, facilitating their coalescence and expulsion. This combination is widely used in India for symptomatic relief of abdominal pain, bloating, and discomfort associated with functional gastrointestinal disorders like Irritable Bowel Syndrome (IBS) and functional dyspepsia.
| Onset | Duration | Bioavailability |
|---|---|---|
| Dicyclomine: 1-2 hours (oral). Simethicone: Rapid, within minutes of reaching the GI tract. | Dicyclomine: Approximately 4-6 hours. Simethicone: Transient, requires repeated dosing with meals. | Dicyclomine: ~67-73% (oral). Simethicone: Not systemically absorbed; acts locally in the GI lumen. |
2. Mechanism of Action
Dicyclomine competitively inhibits muscarinic acetylcholine receptors (M1, M2, M3) on smooth muscle cells in the gastrointestinal tract, leading to direct smooth muscle relaxation and reduction of spasmodic contractions. Simethicone is a silicone polymer that lowers the surface tension of gas bubbles trapped in the GI mucus and chyme, causing them to coalesce into larger bubbles. This allows for easier elimination via belching or flatus, relieving bloating and pressure.
3. Indications & Uses
- Symptomatic relief of abdominal pain, cramps, and bloating associated with Irritable Bowel Syndrome (IBS)
- Symptomatic relief of functional dyspepsia with bloating and flatulence
- Relief of symptoms due to diverticular disease
4. Dosage & Administration
Adult Dosage: 1 tablet (Dicyclomine 10mg + Simethicone 40mg) three to four times daily, preferably 20-30 minutes before meals and at bedtime. The dose should be titrated to the lowest effective dose.
Administration: Take tablet with a full glass of water. Can be taken before meals to prevent post-prandial symptoms and at bedtime if nocturnal symptoms occur. Do not crush or chew unless advised. Avoid taking immediately after antacids.
5. Side Effects
Common side effects may include:
- Dry mouth
- Blurred vision/ difficulty in accommodation
- Drowsiness, dizziness
- Constipation
- Nausea
- Headache
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Other Anticholinergics (e.g., Atropine, Trihexyphenidyl, Antihistamines, TCAs) | Additive anticholinergic side effects (dry mouth, constipation, urinary retention, confusion). | Major |
| Amantadine | Enhanced anticholinergic side effects and risk of psychosis. | Moderate |
| Potassium Chloride (wax-matrix formulations) | Dicyclomine may slow GI transit, increasing risk of GI mucosal injury from KCl. | Moderate |
| Metoclopramide, Domperidone | Pharmacological antagonism; dicyclomine reduces GI motility, counteracting prokinetic effects. | Moderate |
| Opioid Analgesics (e.g., Codeine, Tramadol) | Severe constipation and additive CNS depression. | Major |
| Benzodiazepines, Alcohol, CNS Depressants | Additive sedation and dizziness. | Moderate |
| Digoxin | Increased digoxin absorption (theoretical due to reduced motility), potentially increasing toxicity. | Moderate |
| Antacids, Adsorbents (e.g., Kaolin) | May reduce absorption of dicyclomine. Administer at least 2 hours apart. | Minor |
7. Patient Counselling
- Do take the tablet 20-30 minutes before meals if symptoms are meal-related.
- Do drink plenty of fluids to avoid constipation.
- Do inform your doctor if you have glaucoma, prostate problems, or heart disease.
- Don't drive or operate heavy machinery if you feel drowsy or dizzy.
- Don't take it with alcohol.
- Don't take antacids within 2 hours of taking this medicine.
8. Toxicology & Storage
Overdose: Symptoms are primarily due to dicyclomine and are anticholinergic: CNS (headache, dizziness, seizures, respiratory failure, coma), cardiovascular (tachycardia, palpitations, hypotension, circulatory collapse), hyperthermia, flushed dry skin, dry mouth, dilated pupils, blurred vision, urinary retention, ileus.
Storage: Store below 30°C, in a cool, dry place, protected from light and moisture. Keep out of reach of children.