A fixed-dose combination (FDC) of a proton pump inhibitor (Omeprazole) and an antispasmodic/anticholinergic agent (Dicyclomine). Omeprazole suppresses gastric acid secretion by irreversibly inhibiting the H+/K+ ATPase enzyme system (proton pump) of the gastric parietal cell. Dicyclomine relieves smooth muscle spasm of the gastrointestinal tract via its direct antispasmodic action and weak anticholinergic (antimuscarinic) effects. This combination is primarily used for the symptomatic relief of acid-peptic disorders accompanied by visceral smooth muscle spasm and hypermotility, such as certain types of functional dyspepsia and irritable bowel syndrome (IBS).
Adult: One tablet (Omeprazole 10mg + Dicyclomine 10mg) twice daily, 15-30 minutes before meals. For functional dyspepsia/IBS, the duration is typically short-term (2-4 weeks). Maximum: 2 tablets twice daily (under medical supervision).
Note: Swallow the tablet whole with a glass of water; do not crush, chew, or break. Should be taken on an empty stomach, at least 15-30 minutes before a meal (preferably breakfast and dinner) for optimal acid suppression by omeprazole. Avoid taking immediately after food.
The combination works via two distinct mechanisms. Omeprazole is a prodrug that accumulates in the acidic environment of the parietal cell canaliculi, where it is activated to a sulfenamide. This active form covalently and irreversibly binds to cysteine residues on the H+/K+ ATPase (proton pump), inhibiting the final step of gastric acid secretion. Dicyclomine hydrochloride exerts a direct relaxant effect on visceral smooth muscle (via nonspecific spasmolytic action) and also possesses weak antimuscarinic activity. It blocks the action of acetylcholine at muscarinic receptors in the GI tract, reducing spasmodic contractions, motility, and secretory activity.
Pregnancy: Omeprazole: Category C (US FDA). Animal studies have shown risk, but human data is limited. Use only if potential benefit justifies potential risk to the fetus. Dicyclomine: Category B (US FDA). However, some studies suggest a possible association with fetal harm. Avoid in pregnancy, especially in the first trimester, unless clearly needed. Consult an obstetrician.
Driving: Dicyclomine may cause dizziness, drowsiness, or blurred vision. Patients should be cautioned about driving or operating machinery until they know how the medication affects them.
| Clopidogrel | Omeprazole (a CYP2C19 inhibitor) may reduce the antiplatelet effect of clopidogrel (a prodrug activated by CYP2C19), potentially increasing cardiovascular risk. | Major |
| Diazepam, Phenytoin, Warfarin | Omeprazole may inhibit CYP2C19, potentially increasing plasma levels and effects/toxicity of these drugs. | Moderate |
| Ketoconazole, Itraconazole, Iron salts, Dabigatran | Omeprazole reduces gastric acidity, which may decrease the absorption of these drugs. | Moderate |
| Methotrexate (especially high-dose) | Omeprazole may decrease renal clearance of methotrexate, leading to increased levels and toxicity. | Major |
| Rilpivirine, Atazanavir, Nelfinavir | PPIs reduce absorption of these HIV drugs due to increased gastric pH, leading to loss of virologic response. | Major |
| Digoxin | Increased gastric pH may slightly increase bioavailability of digoxin. | Minor |
| Other Anticholinergics (e.g., tricyclic antidepressants, antihistamines, antipsychotics) | Additive anticholinergic side effects (dry mouth, constipation, urinary retention, blurred vision, confusion) with dicyclomine. | Moderate |
| Amantadine | Enhanced anticholinergic side effects. | Moderate |
| Alcohol, CNS Depressants | Dicyclomine may have additive sedative effects. | Moderate |
| Metoclopramide | Pharmacological antagonism; dicyclomine reduces GI motility, counteracting metoclopramide's prokinetic effect. | Moderate |