Pilocarpine
A plant-derived muscarinic agonist used as eye drops for glaucoma and as tablets for dry mouth.
Drug card
- How it works
- Activating muscarinic receptors, so glands secrete and smooth muscle contracts
- Used for
- Glaucoma, including acute angle-closure attacks
- Dry mouth after radiotherapy or in Sjögren's syndrome
- Age-related blurred near vision (presbyopia)
- Known for
- Heavy sweating
- Blurred or dim vision, worse in poor light
Study it as a flashcard, and it comes back before you forget it.
Mechanism of action
How does pilocarpine work?
An alkaloid from Pilocarpus plants that acts mainly on muscarinic receptors. In the eye it contracts the iris sphincter (miosis) and the ciliary muscle, which opens the trabecular meshwork so aqueous humor drains and eye pressure falls. Taken by mouth it drives the salivary and sweat glands to secrete.
Like other direct-acting muscarinic agonists: They bind to muscarinic acetylcholine receptors and switch them on, copying the parasympathetic nervous system. Glands then secrete more saliva, sweat and tears, the bladder's detrusor and the gut wall contract, the pupil narrows and the heart can slow. Bethanechol, a choline ester, is not broken down by cholinesterase, so it acts for longer than acetylcholine.
Uses
What is pilocarpine used for?
- Glaucoma, including acute angle-closure attacks
- Dry mouth after radiotherapy or in Sjögren's syndrome
- Age-related blurred near vision (presbyopia)
Side effects
Side effects of pilocarpine
- Heavy sweatingKnown for
- Blurred or dim vision, worse in poor lightKnown for
- Headache and brow ache
- Nausea
- Flushing and chills
- Passing urine more often
- Dizziness
- Weakness and tiredness
- Diarrhea
- Low blood pressure
- Eye irritation, pain and redness
- Retinal tear or detachment (rare)Serious
Known for marks what an exam expects you to know it for.
Watch for
Cautions and what sets it apart
- Uncontrolled asthma is a contraindication for the tablets: pilocarpine raises airway resistance and bronchial secretions.
- Acute iritis: avoid it when a constricted pupil is unwanted.
- Pre-existing retinal disease raises the risk of retinal detachment; the retina is examined before eye drops start.
- Significant heart disease: it can push heart rate and blood pressure up or down.
Good to know: A plant alkaloid rather than a choline ester like bethanechol, and used both as eye drops and as tablets.
Remember it
A way to remember it
SLUDGE
- S
- Salivation
- L
- Lacrimation (watery eyes)
- U
- Urination (urgency and frequency)
- D
- Defecation (diarrhea)
- G
- GI cramps
- E
- Emesis (vomiting)
A mnemonic widely used in teaching
Its class
Direct-acting muscarinic agonists
Other direct-acting muscarinic agonists with a card:
Easily mixed up with anticholinesterases and antimuscarinics.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
- Pilocarpine hydrochloride tablets: label (DailyMed)
- Pilocarpine hydrochloride ophthalmic solution: label (DailyMed)
- Pilocarpine hydrochloride ophthalmic solution for presbyopia: label (DailyMed)
- Pilocarpine (NCI Thesaurus)
For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.
Autonomic nervous system
Pilocarpine is one of 10 drugs practiced together here: their classes, how they work, what they treat and what they're known for.
Start Practicing