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# Dicyclomine hydrochloride
## Overview
Dicyclomine is an antispasmodic and anticholinergic agent that acts primarily by direct relaxation of smooth muscle in the gastrointestinal tract and antagonism of muscarinic acetylcholine receptors.
## Primary Indications
Symptomatic treatment of functional bowel/irritable bowel syndrome (IBS).
## Adult Dosing
* **Oral:** Initial dose is 20 mg four times daily. If tolerated and ineffective after one week, dose may be increased to 40 mg four times daily.
* **Intramuscular (IM):** 20 mg every 4 to 6 hours. Not for intravenous use. (IM route used only when oral therapy is not feasible).
* **Maximum Dose:** 160 mg/day (40 mg qid).
## Pediatric Dosing
* **Safety/Efficacy:** Not recommended for use in pediatric patients due to the risk of serious anticholinergic side effects (e.g., respiratory distress, seizures, syncope). Historically, some protocols suggested 5–10 mg 3–4 times daily, but this is largely unsupported by current evidence and discouraged.
## Dose Adjustments
* **Renal Impairment:** Use with caution. No standardized formal dose reduction, but monitor for accumulation and prolonged anticholinergic toxicity.
* **Hepatic Impairment:** Use with caution; monitor for increased sensitivity to anticholinergic effects.
* **Geriatric:** Use with extreme caution. Dicyclomine is on the Beers Criteria list as a drug to avoid in older adults due to high risk of confusion, urinary retention, and constipation.
## Contraindications
* Infants (< 6 months).
* Unstable cardiovascular status in acute hemorrhage.
* Myasthenia gravis.
* Obstructive diseases of the GI tract (e.g., pyloroduodenal stenosis, paralytic ileus).
* Severe ulcerative colitis or toxic megacolon.
* Glaucoma.
* Reflux esophagitis.
## Adverse Effects
* **Common:** Dry mouth, dizziness, blurred vision, constipation, nausea, somnolence, and weakness.
* **Serious:** Anticholinergic psychosis (especially in elderly), urinary retention, tachycardia, heat prostration (decreased sweating), and anaphylaxis.
## Key Drug Interactions
* **Anticholinergics:** Additive effects (e.g., antihistamines, tricyclic antidepressants, antipsychotics) increase risk of toxicity.
* **Digoxin:** Dicyclomine may increase serum digoxin concentrations by slowing gut motility, increasing absorption.
* **Potassium Chloride:** Increased risk of GI mucosal ulceration due to delayed transit time.
## Monitoring
* Monitor heart rate (tachycardia).
* Assess for constipation or signs of bowel obstruction.
* Monitor mental status (confusion, hallucinations/delirium), especially in geriatric populations.
* Monitor urinary output in patients at risk for retention (e.g., BPH).
## Clinical Pearls
* **Administration:** Take before meals if possible.
* **Safety warning:** Avoid use of heat lamps or strenuous exercise in hot environments, as dicyclomine inhibits sweating and may induce heat stroke.
* **Cognitive impact:** Sudden discontinuation may be necessary if the patient exhibits confusion or cognitive decline.
* **Route:** Ensure IM doses are never administered intravenously.
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**Educational Disclaimer:** This information is for educational purposes only. Always consult current, full prescribing information (package insert) or institutional clinical protocols before prescribing or administering medication. Confirm doses based on patient-specific factors such as age, weight, and renal/hepatic function.
