Dicyclomine HCl

 

1. Generic & Brand Names

• Generic: Dicyclomine HCl

• Brands: Bentyl® (US/Canada), Antispas® (EU), Dibent® (India)

• Formulations:

  • Tablets (10mg, 20mg)

  • Capsules (10mg, 20mg)

  • Oral solution (10mg/5mL)

  • Injectable (10mg/mL) - IM only

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2. Drug Class & Mechanism

• Class: Anticholinergic/Antispasmodic

• Mechanism:

  • Blocks muscarinic acetylcholine receptors in GI smooth muscle → ↓ spasms

  • Reduces gastric motility → relieves cramping/pain

  • Minimal CNS effects vs. other anticholinergics

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3. FDA-Approved Uses

Condition	Key Applications
Irritable Bowel Syndrome (IBS)	Abdominal pain/cramping relief
Functional GI Disorders	Colitis, diverticulitis spasms
Off-label:	Renal/biliary colic

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4. Dosing Regimens

Group	Acute Dose	Maintenance	Max Daily
Adults	20 mg QID (before meals)	10-20 mg TID-QID	80 mg
Elderly	10 mg BID-TID	5-10 mg BID	30 mg
Administration Rules:

• Take 15-30 min BEFORE meals

• Start low (10 mg) → titrate to avoid side effects

• Avoid >2 weeks without reevaluation

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5. Black Box Warnings & Contraindications

• 🚫 Absolute Contraindications:

  • Infants <6 months (↑ seizure risk)

  • Glaucoma (angle-closure)

  • Myasthenia gravis

  • Severe ulcerative colitis

  • GI obstruction

• High-Risk Groups:

  • Elderly (>65 yrs): ↑ confusion/urinary retention

  • Autonomic neuropathy (e.g., diabetes)

  • Benign prostatic hyperplasia (BPH)

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6. Side Effects

Common (≥20%)	Serious (<1%)
Dry mouth	Tachycardia
Dizziness	Urinary retention
Blurred vision	Paralytic ileus
Constipation	Heat stroke (↓ sweating)
Nausea	Acute glaucoma

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7. Critical Drug Interactions

Medication	Risk	Action
Other Anticholinergics	Scopolamine, TCAs	↑ Toxicity → avoid combo
Opioids	↑ Constipation/ileus risk	Monitor bowel function
Alcohol	↑ Sedation	Avoid
CNS Depressants	Benzodiazepines, antipsychotics	↓ Dose both agents

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8. Special Populations

Group	Recommendation
Pregnancy (Cat B)	Use only if benefit > risk
Lactation	Avoid (infant anticholinergic effects)
Children	Contraindicated <6 months; limited data >6 months
Renal/Hepatic	Max 10 mg BID

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9. Clinical Use for IBS

• Target Symptoms: Cramping, urgency, abdominal pain

• Avoid for: Predominant constipation (IBS-C)

• Combine with:

  • Fiber supplements (psyllium)

  • Low-FODMAP diet

  • Probiotics (e.g., Bifidobacterium infantis)

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10. Administration Alerts

• IM Injection Only:

  • Never give IV (causes thrombosis)

  • Rotate injection sites

• Oral Solution:

  • Measure with calibrated syringe (not spoon)

  • Shake well before use

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Clinical Practice Tips

✅ Effective When:

• Spasms triggered by meals/stress

• IBS with diarrhea (IBS-D) predominance

• Acute cramping episodes
  ❌ Ineffective For:

• Inflammatory causes (e.g., Crohn's disease)

• Chronic pain without spasms

• Bloating/gas relief

⚠️ Safety Monitoring:

• Assess for urinary retention (post-void residual volume if suspected)

• Check intraocular pressure if glaucoma risk

• Discontinue if confusion/hallucinations occur

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Dicyclomine vs. Alternative Antispasmodics

Parameter	Dicyclomine	Hyoscyamine	Mebeverine
CNS Penetration	Low	Moderate	None
Onset	1-2 hours	30 min	1 hour
IBS Evidence	Moderate	Limited	Strong (EU/Asia)
Safety in Elderly	High risk	High risk	Low risk

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Patient Counseling

1. "Take before meals to prevent spasms."

2. "Discontinue if:

   • Eye pain/redness (glaucoma)

   • Difficulty urinating

   • Severe constipation"

3. "Avoid heat exposure – reduces sweating → heat stroke risk."

4. "Limit driving until dizziness assessed."

💡 Pro Tip: For IBS-D, combine with loperamide (imodium) for diarrhea control after spasm relief.

Prescribing Status: Rx-only; avoid long-term use (>3 months).
Cost: Generic tablets cost <$0.10/dose.

Sources: ACG IBS Guidelines (2021), FDA Safety Review (2020).