Contraindications and Interactions of Dicyclomine and Metoclopramide

Pharmacologic Antagonism

Dicyclomine is an anticholinergic antispasmodic that relaxes smooth muscle by blocking muscarinic receptors, thereby slowing gastrointestinal motility, which is opposed to the prokinetic effects of metoclopramide 1

For gastroparesis or delayed gastric emptying, the American Diabetes Association recommends using metoclopramide (reserved for severe cases unresponsive to other therapies, limited to ≤12 weeks due to risk of tardive dyskinesia) 2
For irritable bowel syndrome with abdominal pain and spasm, the European Society of Gastrointestinal Motility recommends using dicyclomine or other antispasmodics 1
For nausea with normal or rapid gut motility, the American Gastroenterological Association suggests considering antiemetics without prokinetic effects (ondansetron, promethazine) rather than metoclopramide 4

The National Comprehensive Cancer Network recommends avoiding metoclopramide entirely in patients with complete bowel obstruction (prokinetics are contraindicated and could increase pressure on obstructed segments) 6
The American College of Cardiology advises that anticholinergics can mask early warning signs of metoclopramide's serious neurological adverse effects (extrapyramidal symptoms, tardive dyskinesia) 3