Hyoscyamine (Levsin): An Anticholinergic Medication for GI Disorders
Hyoscyamine (Levsin) is an anticholinergic medication primarily used to treat gastrointestinal disorders by reducing smooth muscle spasms, decreasing gastric secretions, and controlling hypermotility in conditions such as irritable bowel syndrome, spastic colon, and functional gastrointestinal disorders. 1
Mechanism of Action
Hyoscyamine works through:
- Anticholinergic/antimuscarinic effects that inhibit gastrointestinal smooth muscle contractions
- Blocking muscarinic receptors in the GI tract, resulting in smooth muscle relaxation
- Reducing gastric secretions and hypermotility
Clinical Indications
Hyoscyamine is FDA-approved for:
Primary indications:
- Adjunctive therapy in peptic ulcer disease
- Control of gastric secretion and visceral spasm
- Treatment of spastic conditions including:
- Spastic colitis
- Irritable bowel syndrome
- Functional gastrointestinal disorders
- Diverticulitis
- Acute enterocolitis
Secondary indications:
- Adjunctive therapy for neurogenic bladder and bowel disturbances
- Relief of biliary and renal colic (when used with opioids)
- Treatment of infant colic (elixir and drops formulation)
- Symptomatic relief in parkinsonism to reduce rigidity, tremors, and control sialorrhea
- As a "drying agent" for acute rhinitis symptoms 1
Dosage Forms
Hyoscyamine is available in multiple formulations:
- Oral drops (0.125 mg/mL with 5% alcohol)
- Elixir (0.125 mg per 5 mL with 20% alcohol)
- Tablets (standard and sublingual) 1
Clinical Applications in Guidelines
Hyoscyamine is recommended in clinical guidelines for:
Diarrhea management in palliative care:
GI symptoms in hypermobile Ehlers-Danlos syndrome:
- Recommended as an antispasmodic for abdominal pain management
- Listed alongside other antispasmodics like dicyclomine and peppermint oil 2
Pharmacokinetics
- Readily absorbed through the gastrointestinal tract
- Reaches peak effects in 2-2.5 hours
- Excreted in urine within 24 hours 3
Clinical Efficacy
Hyoscyamine has demonstrated effectiveness in:
- Reducing GI smooth muscle spasms
- Controlling symptoms in irritable bowel syndrome
- Managing functional intestinal disorders
- Facilitating diagnostic procedures like colonoscopy and ERCP by reducing intestinal motility 4, 5
Adverse Effects and Precautions
Common side effects include:
- Dry mouth
- Blurred vision
- Urinary retention
- Tachycardia (reported in 27% of patients in one study) 4
- Constipation
- Dizziness
Important precautions:
- Use with caution in patients with glaucoma, prostatic hypertrophy, or cardiac conditions
- Avoid in patients with myasthenia gravis, paralytic ileus, or intestinal atony
- Monitor for anticholinergic side effects, especially in elderly patients
Clinical Decision Making
When considering hyoscyamine for GI disorders:
First-line use:
- Acute management of abdominal cramping and pain associated with GI spasms
- Short-term treatment of irritable bowel syndrome symptoms
- Adjunctive therapy in functional GI disorders
Alternative options to consider:
- Other antispasmodics (dicyclomine, peppermint oil)
- For severe diarrhea in palliative care, consider adding octreotide if hyoscyamine is insufficient 2
Practical Considerations
- Hyoscyamine is generally well-tolerated but monitor for anticholinergic side effects
- The medication can be particularly useful in palliative care settings for symptom management
- When used for diagnostic procedures, be aware of the potential for tachycardia 4
- Consider cost-effectiveness compared to alternatives (significantly less expensive than glucagon when used as an antimotility agent for procedures) 5
Hyoscyamine remains a valuable option in the treatment armamentarium for GI disorders characterized by spasm and hypermotility, with particular utility in palliative care settings and as adjunctive therapy for functional GI disorders.