What are the contraindications to using Bentyl (dicyclomine)?

Contraindications to Using Bentyl (Dicyclomine)

Bentyl (dicyclomine) is absolutely contraindicated in infants less than 6 months of age, nursing mothers, and patients with unstable cardiovascular status, myasthenia gravis, glaucoma, obstructive uropathy, obstructive gastrointestinal disease, severe ulcerative colitis, and reflux esophagitis 1.

Absolute Contraindications

Dicyclomine hydrochloride should not be used in patients with:

• Infants less than 6 months of age - Safety concerns have led to this strict contraindication
• Nursing mothers - The drug is distributed into breast milk
• Myasthenia gravis - Can worsen neuromuscular blockade leading to muscle weakness and possible paralysis
• Glaucoma - Particularly angle-closure glaucoma due to anticholinergic effects
• Obstructive uropathy - Can worsen urinary retention
• Obstructive gastrointestinal disease - Can precipitate or worsen intestinal obstruction
• Severe ulcerative colitis - Risk of toxic megacolon
• Reflux esophagitis - Can worsen symptoms
• Unstable cardiovascular status in acute hemorrhage - May worsen cardiovascular instability

Relative Contraindications and Precautions

Dicyclomine should be used with extreme caution in:

• Elderly patients - Increased susceptibility to anticholinergic side effects including confusion, hallucinations, and cognitive impairment
• Prostatic hypertrophy - Risk of urinary retention
• Hepatic and renal impairment - Altered drug metabolism and clearance
• Coronary heart disease - May worsen ischemia and infarction
• Hypertension - May exacerbate elevated blood pressure
• Autonomic neuropathy - Increased sensitivity to anticholinergic effects
• Fever or high environmental temperature - Risk of heat prostration due to decreased sweating
• Patients with Salmonella dysentery - Risk of toxic dilatation of intestine and intestinal perforation
• Mild to moderate ulcerative colitis - May precipitate toxic megacolon

Mechanism-Related Concerns

The anticholinergic properties of dicyclomine can cause significant adverse effects:

1. Peripheral effects:

   • Dry mouth, difficulty swallowing
   • Reduced bronchial secretions
   • Mydriasis (pupil dilation) with loss of accommodation
   • Skin flushing and dryness
   • Cardiac effects (bradycardia followed by tachycardia, palpitations, arrhythmias)
   • Urinary retention
   • Reduced GI motility leading to constipation

2. Central nervous system effects:

   • Confusion, disorientation
   • Amnesia, hallucinations
   • Dysarthria, ataxia
   • Euphoria, fatigue, insomnia
   • Agitation and inappropriate affect
   • Psychosis and delirium (especially in elderly or those with mental illness)

Special Populations

• Pregnancy: Use with caution as safety data is limited
• Pediatric use: Contraindicated in infants under 6 months; use with caution in older children
• Geriatric use: Use with caution due to increased sensitivity to anticholinergic effects

Administration Concerns

• Intravenous administration: Should be avoided due to potential for thrombosis 2
• Driving and operating machinery: May cause drowsiness, dizziness, or blurred vision

Clinical Pearls

1. Monitor patients closely when initiating therapy, particularly those with cardiovascular conditions
2. Be vigilant for signs of incomplete intestinal obstruction, especially in patients with ileostomy or colostomy
3. Watch for development of Ogilvie's syndrome (colonic pseudo-obstruction)
4. Consider alternative therapies in patients with multiple contraindications or precautions
5. Educate patients about potential anticholinergic side effects and when to seek medical attention

By understanding these contraindications and using appropriate caution, clinicians can safely prescribe dicyclomine for appropriate indications while minimizing risks to patients.