Dicyclomine

Dicyclomine is a synthetic antimuscarinic medication used mainly to relieve symptoms of irritable bowel syndrome (IBS), such as abdominal cramps and spasms. It is commonly available as dicyclomine hydrochloride in oral tablet or capsule forms, and is also supplied as an injectable preparation for certain clinical settings.

Mechanism of action and indications

Dicyclomine acts as a competitive antagonist of muscarinic acetylcholine receptors, with antispasmodic effects on the smooth muscle of the gastrointestinal tract. By reducing smooth muscle tone and contractions, it helps lessen cramps and discomfort associated with IBS and other GI conditions.

Administration and dosing

In adults, dicyclomine is typically prescribed for short-term use, often in doses around 20 mg four times daily, with a maximum daily limit commonly cited near 160 mg. Dosing for children and actual regimens should follow a clinician’s guidance. The injectable form is used in specific hospital or preoperative contexts.

Contraindications and warnings

Dicyclomine should not be used in people with narrow-angle glaucoma, obstructive GI diseases (including ileus and intestinal atony), urinary retention, severe ulcerative colitis, or certain neuromuscular conditions such as myasthenia gravis. Caution is advised in older adults due to the risk of cognitive and other anticholinergic effects.

Side effects and interactions

Common adverse effects include dry mouth, blurred vision, dizziness, constipation, and tachycardia. Dicyclomine can worsen urinary retention and confusion in susceptible individuals. It can interact with other anticholinergic drugs and medications with sedative effects, and alcohol may enhance these effects.

Pharmacokinetics and notes

Dicyclomine is absorbed orally and undergoes hepatic metabolism with renal excretion of metabolites. It is available as a generic medication and has a history of use since the mid-20th century for GI spasm relief.