Pharmacology · Muscarinic (cholinergic) agonists
Pilocarpine !
A muscarinic agonist used as eye drops to lower eye pressure in glaucoma, and as tablets to relieve dry mouth in Sjögren disease or after radiotherapy.
Updated 2026-11-01
No structure of pilocarpine bound to its receptor exists. The figure shows iperoxo, a potent research agonist, in the acetylcholine (orthosteric) pocket of the active human M3 muscarinic receptor, the subtype on glands, the eye and the bladder that pilocarpine stimulates.
Mechanism of action
Pilocarpine directly stimulates muscarinic receptors. In the eye it contracts the ciliary muscle, which pulls on the scleral spur and opens the spaces of the trabecular meshwork, so aqueous humour drains out and eye pressure falls; it also contracts the iris sphincter (miosis), which pulls the iris away from a closed angle. Taken by mouth it stimulates salivary and other exocrine glands.
- Activates M3 receptors in the eye or glands
- Ciliary muscle contracts and opens the trabecular meshwork
- Aqueous humour drains and eye pressure falls
- By mouth: saliva and sweat increase
Pharmacokinetics
- Absorption
- Eye drops act locally; tablets are absorbed by mouth
- Distribution
- Tertiary amine: can enter the brain
- Half-life
- About one hour after tablets
Indications
- Open-angle glaucoma and ocular hypertension (eye drops) Open-angle glaucoma →
- Acute angle-closure glaucoma (eye drops) Acute angle-closure glaucoma →
- Prevention of pressure rises after laser eye surgery; presbyopia (low-strength drops)
- Dry mouth in Sjögren disease (tablets) Sjögren disease →
- Dry mouth from salivary gland damage after radiotherapy for head and neck cancer (tablets)
Adverse effects
Common
- Eye drops: headache or brow ache, blurred vision, dim vision at night, eye irritation
- Tablets: sweating (the most common reason to stop), nausea, runny nose, diarrhoea, chills, flushing, frequent urination, dizziness
Contraindications
- Tablets: uncontrolled asthma
- Tablets: when miosis is undesirable, as in acute iritis
- Hypersensitivity to pilocarpine
- Eye drops not recommended when iritis is present
Key interactions
- Beta blockers
- Possible heart conduction disturbances
- Antimuscarinic drugs
- Each opposes the other
- Other parasympathomimetics
- Additive cholinergic effects
What is monitored
- Eye pressure and visual field in glaucoma
- Retina examination before starting eye drops
- Breathing in asthma or COPD; heart rate and blood pressure in heart disease
Administration and safety
- Eye drops: the dropper tip does not touch the eye; contact lenses are removed and put back about 10 minutes later
- Sudden flashes, floaters or a curtain over vision are reported at once
- Tablets: heavy sweating can lead to dehydration
Nursing care
- Warn about poor vision at night and driving in dim light
- Teach eye-drop technique and handwashing
- Watch for wheeze in people with lung disease
- Encourage fluids to avoid dehydration from sweating
Pregnancy and breastfeeding
Human data are lacking; it is used in pregnancy only if clearly needed.
Test yourself
Think of the answer, then tap the question to see it.
How do pilocarpine eye drops lower eye pressure?
They contract the ciliary muscle, which opens the trabecular meshwork and increases outflow of aqueous humour.
What is the most common side effect of pilocarpine tablets?
Sweating.
Why is a retina exam advised before starting pilocarpine eye drops?
Miotics have rarely caused retinal detachment in susceptible eyes.
Related drugs
Related conditions
← Back to the class: Muscarinic (cholinergic) agonists
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - PILOCARPINE HYDROCHLORIDE solution/ drops (DailyMed (U.S. National Library of Medicine), 2026); DailyMed - PILOCARPINE HYDROCHLORIDE tablet, film coated (DailyMed (U.S. National Library of Medicine), 2026); Pilocarpine Ophthalmic: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); eEML - Electronic Essential Medicines List (World Health Organization, 2025).
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Representative model, for educational purposes only.