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# Dicyclomine hydrochloride
## Overview
Dicyclomine is an antispasmodic/anticholinergic agent that acts directly on smooth muscle to relieve spasm and by antagonizing acetylcholine and histamine receptors. It has limited antisecretory activity.
## Primary Indications
Treatment of functional bowel/irritable bowel syndrome (IBS).
## Adult Dosing
* **Initial:** 20 mg orally 4 times daily.
* **Maintenance:** May increase to 40 mg 4 times daily after one week if tolerated.
* **Maximum:** 160 mg/day (40 mg qid). Discontinue if efficacy is not achieved within 2 weeks.
## Pediatric Dosing
* **Safety/Efficacy:** Not established for infants <6 months old; contraindicated in this population due to risk of serious respiratory/CNS adverse events.
* **Children (≥6 months):** 5 mg orally 3 to 4 times daily, increasing to 10 mg 3 to 4 times daily as tolerated. Dosing varies by institutional protocol; clinical judgment is required.
## Dose Adjustments
* **Renal/Hepatic Impairment:** No specific guidelines; use with caution.
* **Geriatric Patients:** Use with extreme caution (Beer’s Criteria). Start at lowest possible dose due to high susceptibility to anticholinergic side effects (confusion, urinary retention, constipation).
## Contraindications
* Infants (<6 months).
* Unstable cardiovascular status in acute hemorrhage.
* Myasthenia gravis.
* Obstructive disease of the GI tract (e.g., pyloroduodenal stenosis).
* Paralytic ileus or intestinal atony.
* Severe ulcerative colitis or toxic megacolon.
* Glaucoma.
* Prostatic hypertrophy/urinary bladder neck obstruction.
## Adverse Effects
* **Common:** Dry mouth, dizziness, blurred vision, nausea, drowsiness, nervousness, and constipation.
* **Serious:** Tachycardia, palpitations, urinary retention, confusion/hallucinations (often in elderly), and heatstroke (decreased sweating).
## Key Drug Interactions
* **Anticholinergics:** Additive toxicity (e.g., antihistamines, tricyclic antidepressants, antipsychotics).
* **Digoxin:** Dicyclomine may increase serum concentration by decreasing gastric motility/increasing absorption.
* **Antacids:** May interfere with the bioavailability of dicyclomine; administer separately.
## Monitoring
* Monitor for signs of anticholinergic toxicity (tachycardia, urinary retention, mental status changes).
* Assess for therapeutic efficacy; discontinue if symptoms do not improve.
* Monitor GI function (constipation).
## Clinical Pearls
* Avoid use in hot weather or during physical exercise; the drug may cause heat prostration due to decreased sweating.
* Warn patients regarding drowsiness; avoid activities requiring mental alertness (driving/operating machinery).
* Not recommended for the long-term management of chronic conditions other than IBS.
* Consider non-pharmacologic management (dietary modification/stress reduction) as first-line therapy.
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**Disclaimer:** This information is for educational purposes only. Clinical practice guidelines and local protocols vary. Verify all dosing and contraindications via official prescribing information, hospital formulary software, or Lexicomp/UpToDate before prescribing or administering.
