Dicyclomine oral tablets and capsules for irritable bowel syndrome

Dicyclomine is an antispasmodic and anticholinergic medication used to treat functional bowel disorders such as irritable bowel syndrome (IBS). It works by relaxing the smooth muscles of the gastrointestinal tract to relieve intestinal spasms and associated abdominal pain. Available as oral tablets and capsules, dicyclomine is typically prescribed for short-term use in adults.

Dicyclomine hydrochloride is indicated for the treatment of patients with functional bowel or irritable bowel syndrome (IBS), helping to reduce bowel spasms.

Dicyclomine hydrochloride

Dicyclomine works by blocking muscarinic receptors (antimuscarinic effect) which reduces the action of acetylcholine in the gut. This leads to relaxation of smooth muscle, decreasing spasms and motility. It also has a direct relaxing effect on smooth muscle, making it effective against intestinal cramps. Additionally, it inhibits secretions such as saliva and sweat.

Adults (Oral tablets and capsules):

• Starting dose: 20 mg four times daily.
• After 1 week, may increase dose to 40 mg four times daily if tolerated.
• If no efficacy after 2 weeks or if side effects require dose below 80 mg daily, discontinue treatment.
• Safety data for doses above 80 mg daily beyond 2 weeks are not available.
• If a dose is missed, continue with the normal dosing schedule.

• Infants under 6 months of age.
• Glaucoma.
• Nursing mothers (breastfeeding).
• Unstable cardiovascular status in acute hemorrhage.
• Myasthenia gravis (except to reduce muscarinic effects of anticholinesterase).
• Obstructive uropathy.
• Obstructive gastrointestinal disease.
• Severe ulcerative colitis.
• Reflux esophagitis.

• Cardiovascular: Use with caution in patients with tachyarrhythmias, thyrotoxicosis, congestive heart failure, coronary heart disease, or hypertension. Investigate tachycardia before use.
• Central and Peripheral Nervous System: May cause drowsiness, dizziness, blurred vision, heat prostration (risk of fever and heat stroke due to decreased sweating), psychosis, delirium, amnesia, hallucinations especially in elderly or those with mental illness. Discontinue if symptoms occur.
• Myasthenia Gravis: Contraindicated except to reduce adverse muscarinic effects of anticholinesterase. Overdose may cause muscular weakness or paralysis.
• Intestinal Obstruction: Contraindicated if incomplete intestinal obstruction suspected; diarrhea can be an early symptom.
• Ulcerative Colitis: Contraindicated in severe cases. Use with caution; high doses may worsen conditions such as toxic megacolon.
• Prostatic Hypertrophy: Use with caution; may cause urinary retention.
• Hepatic and Renal Impairment: Use cautiously in impaired hepatic or renal function.
• Geriatric Patients: Elderly may be more sensitive to side effects; dose with caution.
• Heat Exposure: Be cautious in high environmental temperatures due to risk of heat prostration.

The most common side effects (occurring in more than 5% of patients) include dryness of the mouth, dizziness, blurred vision, nausea, somnolence, asthenia (weakness), and nervousness.

Other reported adverse reactions include palpitations, tachyarrhythmias, cycloplegia, mydriasis, abdominal discomfort, constipation, fatigue, malaise, hypersensitivity reactions (including angioedema and anaphylaxis), headache, syncope, delirium, hallucinations, mood changes, suppressed lactation, dyspnea, nasal congestion, dermatitis, and rash.

Overdosage may lead to neuromuscular blockade causing muscular weakness or paralysis.

• Antiglaucoma Agents: Anticholinergic effects may antagonize antiglaucoma drugs and increase intraocular pressure; use in glaucoma is not recommended.
• Other Anticholinergic Drugs: May increase anticholinergic side effects. Examples include amantadine, class I antiarrhythmics (quinidine), antihistamines, antipsychotics (phenothiazines), benzodiazepines, MAO inhibitors, narcotic analgesics (meperidine), nitrates, sympathomimetics, tricyclic antidepressants.
• Gastrointestinal Motility Drugs: May antagonize drugs like metoclopramide.
• Antacids: May interfere with absorption of dicyclomine; concurrent use should be avoided.
• Other Drugs: May alter absorption of drugs dependent on gastrointestinal motility, e.g., digoxin, possibly increasing serum concentrations.
• Gastric Acid Secretion: Anticholinergic effects on gastric acid secretion may be antagonized by drugs used to treat achlorhydria.

Pregnancy

Category B. Adequate studies in pregnant women are not available. Animal studies did not show harm at doses up to 33 times the human dose. Use only if clearly needed.

Lactation

Contraindicated during breastfeeding. Dicyclomine is excreted in human milk and may cause serious adverse reactions in nursing infants. Consider discontinuing nursing or therapy.

Overdose symptoms include headache, nausea, vomiting, blurred vision, dilated pupils, hot and dry skin, dizziness, dry mouth, difficulty swallowing, and central nervous system stimulation such as convulsions. Neuromuscular blockade leading to muscular weakness or paralysis may occur.

Treatment includes gastric lavage, emetics, activated charcoal, sedation with short-acting barbiturates or benzodiazepines, and use of parenteral cholinergic agents as antidotes if indicated.

Store capsules at 20° to 25°C (68° to 77°F). Protect from light and moisture. Avoid exposure to direct sunlight to prevent fading. Dispense in a tight, light-resistant container with child-resistant closure.