Can Dicyclomine Be Taken With Metoclopramide?
No, dicyclomine should not be taken with metoclopramide because anticholinergic drugs like dicyclomine directly antagonize and counteract the prokinetic effects of metoclopramide on gastrointestinal motility. 1
Pharmacologic Antagonism
The FDA drug label for metoclopramide explicitly states that "the effects of metoclopramide on gastrointestinal motility are antagonized by anticholinergic drugs." 1 This represents a direct pharmacodynamic interaction where:
- Metoclopramide works by enhancing gastrointestinal motility through dopamine antagonism and augmentation of acetylcholine release, increasing gastric emptying and intestinal transit 2, 3
- Dicyclomine is an anticholinergic antispasmodic that relaxes smooth muscle by blocking muscarinic receptors, thereby slowing gastrointestinal motility 4, 5
These mechanisms are fundamentally opposed—one accelerates gut motility while the other inhibits it, making concurrent use therapeutically counterproductive.
Clinical Implications
When treating gastrointestinal symptoms, you must choose between these agents based on the underlying pathophysiology:
- For gastroparesis or delayed gastric emptying: Use metoclopramide (reserved for severe cases unresponsive to other therapies, limited to ≤12 weeks due to risk of tardive dyskinesia) 4, 6
- For irritable bowel syndrome with abdominal pain and spasm: Use dicyclomine or other antispasmodics 4
- For nausea with normal or rapid gut motility: Consider antiemetics without prokinetic effects (ondansetron, promethazine) rather than metoclopramide 4
Important Caveats
Metoclopramide should be avoided entirely in patients with:
- Complete bowel obstruction (prokinetics are contraindicated and could increase pressure on obstructed segments) 4, 1
- Concurrent use of other medications causing extrapyramidal symptoms 1
- Pheochromocytoma (can precipitate hypertensive crisis) 1
The combination poses additional risks beyond simple antagonism:
- Anticholinergics can mask early warning signs of metoclopramide's serious neurological adverse effects (extrapyramidal symptoms, tardive dyskinesia) 6
- Both drugs can cause CNS effects (drowsiness, confusion), which may be additive 1, 5
If a patient is already taking dicyclomine and develops symptoms requiring prokinetic therapy, discontinue the anticholinergic before initiating metoclopramide to allow the prokinetic effect to work and to properly assess therapeutic response. 1