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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 blockade of acetylcholine at muscarinic receptors.
## Primary Indications
* Irritable Bowel Syndrome (IBS).
## Adult Dosing
* **Initial:** 20 mg PO 4 times daily.
* **Titration:** May increase to 40 mg PO 4 times daily after one week if tolerated.
* **Max Dosing:** 160 mg/day (40 mg 4 times daily). If efficacy is not achieved within two weeks or side effects are too severe, discontinue.
## Pediatric Dosing
* **Safety/Efficacy:** Not established for pediatric use. Use is generally discouraged due to reports of serious respiratory and CNS side effects in infants under 6 months.
## Dose Adjustments
* **Renal/Hepatic Impairment:** No specific guidelines available; use with caution.
* **Geriatric:** Start at lower doses and titrate slowly. Avoid in patients over 65 (Beers Criteria) due to anticholinergic burden (increased risk of confusion, urinary retention, and constipation).
## Contraindications
* Infants < 6 months of age.
* Nursing mothers.
* Unstable cardiovascular status in acute hemorrhage.
* Myasthenia gravis.
* Glaucoma (narrow-angle).
* Obstructive uropathy or GI tract pathology (e.g., severe constipation, paralytic ileus, toxic megacolon).
## Adverse Effects
* **Common:** Dry mouth, dizziness, blurred vision, nausea, nervousness, drowsiness, and constipation.
* **Serious:** Tachycardia, palpitations, urinary retention, exacerbation of pre-existing glaucoma, and heatstroke (due to suppressed sweating).
## Key Drug Interactions
* **Anticholinergics:** Enhanced anticholinergic effects (e.g., antihistamines, tricyclic antidepressants, antipsychotics).
* **GI Prokinetics:** May antagonize the effects of metoclopramide or cisapride.
* **Digoxin:** Increased digoxin serum concentrations due to decreased GI motility.
## Monitoring
* Monitor for clinical response (GI symptoms).
* Monitor for signs of anticholinergic toxicity (urinary retention, tachycardia, CNS changes/confusion, severe constipation).
## Clinical Pearls
* Take 30 minutes before meals.
* Dicyclomine has a high potential for CNS effects; patients should avoid operating heavy machinery until the effect of the drug on their cognition is known.
* Not indicated for GERD or other non-IBS chronic GI conditions.
* Inform patients about the risk of heat-related illnesses; the drug reduces sweating, which can lead to hyperthermia in hot environments.
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*Disclaimer: This information is for educational purposes only. Clinical practice guidelines and prescribing information change frequently. Always consult the latest FDA-approved labeling (Package Insert) and your local institutional protocols before prescribing or administering medication.*
