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# Dicyclomine hydrochloride
## Overview
Dicyclomine is an antispasmodic and anticholinergic agent that acts as a competitive antagonist at muscarinic acetylcholine receptors at postganglionic parasympathetic sites on smooth muscle and secretory glands.
## Primary Indications
Functional bowel/irritable bowel syndrome (IBS).
## Adult Dosing
* **Initial:** 20 mg orally 4 times daily.
* **Titration:** After 1 week, may increase to 40 mg 4 times daily if tolerated.
* **Maximum:** 160 mg/day (40 mg qid). Discontinue if efficacy is not achieved after 2 weeks.
## Pediatric Dosing
* **Safety/Efficacy:** Not established for pediatric populations.
* **Special Note:** Use is **contraindicated in infants <6 months of age** due to reports of serious respiratory distress, seizures, and death.
## Dose Adjustments
* **Renal/Hepatic Impairment:** No specific manufacturer guidelines; initiate with caution at the lower end of the dosing range as metabolism and clearance may be affected.
* **Geriatrics:** Generally contraindicated or recommended to avoid due to Beers Criteria (anticholinergic burden, fall risk, and cognitive impairment). If unavoidable, use the lowest effective dose.
## Contraindications
* Infants <6 months.
* Unstable cardiovascular status in acute hemorrhage.
* Myasthenia gravis.
* Obstructive uropathy or gastrointestinal disease (e.g., paralytic ileus, severe ulcerative colitis, megacolon).
* Glaucoma (narrow-angle).
* Reflux esophagitis (worsened by decreased lower esophageal sphincter tone).
## Adverse Effects
* **Common:** Dry mouth, dizziness, blurred vision, nausea, lightheadedness, somnolence, asthenia, and nervousness.
* **Serious:** Tachycardia, palpitations, urinary retention, heatstroke (due to decreased sweating), and psychosis/confusion (especially in the elderly).
## Key Drug Interactions
* **Other Anticholinergics:** Additive toxicity (e.g., antihistamines, tricyclic antidepressants, antipsychotics).
* **Potassium Chloride:** Increased risk of gastrointestinal mucosal lesions/ulceration with solid oral dosage forms.
* **Digoxin:** Decreased gastrointestinal motility may increase digoxin serum concentrations.
## Monitoring
* Monitor for symptom relief and therapeutic efficacy.
* Assess for anticholinergic side effects (urinary output, bowel movements, cognition, vision).
* Monitor heart rate and blood pressure, especially in patients with existing cardiac conditions.
## Clinical Pearls
* Dicyclomine is less effective than other treatments for IBS and should be considered a second-line or adjunctive agent.
* Advise patients to avoid operating heavy machinery or driving if somnolence or blurred vision occurs.
* Counsel patients to avoid extreme heat or vigorous exercise, as dicyclomine can suppress sweat production.
* Do not use to treat constipation-predominant IBS given the medication's nature of slowing GI transit.
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*Disclaimer: This information is for educational purposes only. Drug dosing, contraindications, and interaction profiles can change. Always verify current prescribing information using official drug monographs or clinical decision support software before prescribing or administering medication.*
