What is Pilocarpine?
Pilocarpine is a cholinergic parasympathomimetic agent that binds to muscarinic receptors to stimulate secretion from exocrine glands, particularly salivary, lacrimal, and sweat glands. 1
Mechanism of Action
Pilocarpine exerts its effects through muscarinic receptor activation, predominantly targeting M3 receptors, which triggers increased secretion from multiple glandular systems including salivary, lacrimal, sweat, gastric, pancreatic, and intestinal glands 1
The drug increases salivary flow 2-3 fold compared to placebo, with effects maintained throughout 12 weeks of treatment 2
When administered orally, pilocarpine produces onset of action at 20 minutes, peak effect at 1 hour, and duration of 3-5 hours 1
Clinical Applications
Primary Indications
Sjögren's Syndrome: Licensed worldwide for treatment of dry mouth (xerostomia) and dry eye symptoms in patients with Sjögren's syndrome 3
Radiation-Induced Xerostomia: Approved for treating dry mouth following radiation therapy for head and neck cancers 1, 4
Glaucoma: When applied topically to the eye, it causes miosis and lowers intraocular pressure 1, 5
Efficacy Profile
Pilocarpine shows greater improvement in dry mouth symptoms than dry eye symptoms at the standard 20 mg/day dosage 2
In head and neck cancer patients, 63% showed increased whole saliva flow with 5 mg dosing and 90% with 10 mg dosing after the first dose 1
For Sjögren's syndrome, approximately 50% of patients experience symptom improvement compared to 25% with placebo 4
Dosing and Administration
Standard dosing: 5 mg four times daily (20 mg/day total) for moderate glandular dysfunction 2
Dose escalation: Can be increased to 30 mg/day (7.5 mg four times daily) for enhanced ocular symptom relief 6
Available as oral tablets in 5 mg and 7.5 mg strengths 1
Adverse Effects
Most common: Excessive sweating occurs in over 40% of patients 2
Other parasympathomimetic effects: Urinary frequency, flushing, rhinitis, nausea, and chills 6
Discontinuation rate: Approximately 2% of patients stop treatment due to side effects, primarily sweating 2
Serious toxicity: Overdose can cause bradycardia, hypotension, and muscarinic symptoms, treatable with atropine 7
Contraindications and Precautions
Use with caution in patients with asthma, cardiac arrhythmia, iridocyclitis, and closed-angle glaucoma due to parasympathomimetic effects 4
Pilocarpine may cause paradoxical cardiovascular effects including both hypertension and hypotension, as well as both bradycardia and tachycardia 1