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# Dicyclomine hydrochloride
## Overview
Dicyclomine is an antispasmodic and anticholinergic agent that acts by direct relaxation of smooth muscle in the gastrointestinal tract and by blocking acetylcholine at muscarinic receptors.
## Primary Indications
* Treatment of functional bowel/irritable bowel syndrome (IBS).
## Adult Dosing
* **Initial:** 20 mg orally four times daily.
* **Maintenance:** May be increased to 40 mg four times daily after one week, if tolerated.
* **Discontinue:** If efficacy is not achieved after 2 weeks or if side effects are intolerable.
* **IM Route (only when oral is not feasible):** 20 mg every 4 to 6 hours. Not for IV use.
## Pediatric Dosing
* **Efficacy and safety have not been established in patients <18 years.**
* *Note:* The use of dicyclomine is contraindicated in infants <6 months due to reported fatal respiratory distress and seizures associated with anticholinergic side effects.
## Dose Adjustments
* **Renal/Hepatic Impairment:** No specific manufacturer guidelines, but exercise caution due to systemic anticholinergic accumulation.
* **Geriatric:** Avoid in patients ≥65 years (Beers Criteria) due to high risk of anticholinergic side effects (confusion, urinary retention, sedation). If used, initiate at the lowest possible dose.
## Contraindications
* Infants <6 months.
* Unstable cardiovascular status in acute hemorrhage.
* Myasthenia gravis.
* Obstructive disease of the GI tract (e.g., pyloroduodenal stenosis, non-obstructive intestinal atony).
* Severe ulcerative colitis or toxic megacolon.
* Glaucoma (narrow-angle).
* Reflux esophagitis.
## Adverse Effects
* **Common:** Xerostomia (dry mouth), dizziness, blurred vision, nausea, nervousness, somnolence, and asthenia.
* **Serious:** Urinary retention, tachycardia, confusion/hallucinations (particularly in the elderly), and heat prostration (due to decreased sweating).
## Key Drug Interactions
* **Anticholinergics:** Additive effects (e.g., antihistamines, tricyclic antidepressants, antipsychotics).
* **GI Motility Agents:** May antagonize the effects of metoclopramide or other prokinetic agents.
* **Digoxin:** Increased serum concentrations may occur due to slowed GI motility.
## Monitoring
* Monitor for signs of anticholinergic toxicity (hallucinations, confusion, urinary retention).
* Assess therapeutic response (frequency/severity of abdominal pain/spasms) and discontinue if symptoms do not improve.
## Clinical Pearls
* **Do not administer intravenously;** accidental IV administration has resulted in serious cardiac and neurologic adverse events.
* Advise patients to avoid performing tasks requiring mental alertness until the drug’s effect is known, as it may impair cognition and coordination.
* Counsel patients to remain hydrated and avoid hot environments, as dicyclomine inhibits sweating and increases the risk of heatstroke.
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*Disclaimer: This information is for educational purposes only. Clinical guidelines and prescribing practices may change. Always verify current prescribing information, contraindications, and dosing protocols through institutional resources or official FDA-approved labeling before administration.*
