Pilocarpine
Pilocarpine is a direct-acting parasympathomimetic agent used primarily in veterinary ophthalmology. It stimulates cholinergic receptors, leading to ciliary body muscle contraction and miosis, which facilitates improved aqueous humour outflow and lowers intraocular pressure. While historically used for **glaucoma** management, it has largely been superseded by newer topical drugs like carbonic anhydrase inhibitors and prostaglandin analogues. Additionally, **oral pilocarpine** is utilized to stimulate lacrimation in dogs suffering from neurogenic keratoconjunctivitis sicca (KCS). > **Clinical Warning:** Pilocarpine is rarely used for ophthalmic purposes in cats due to a high risk of potential toxicity.
Mechanism: Pilocarpine is a direct-acting parasympathomimetic that stimulates **cholinergic (muscarinic) receptors**. In the eye: Stimulates cholinergic receptors → **ciliary body muscle contraction** and **miosis** (pupil constriction) → opens the iridocorneal angle → improved aqueous humour outflow → **decreased intraocular pressure (IOP)**. Systemically/Orally: Stimulates exocrine glands → increased lacrimation and salivation.
Dosing by species
- Management of glaucoma · Not specified in text · topical · Not specified in text · Not specified in text · Produces miosis in 10-15 minutes lasting for 6-8 hours. Most common concentration used in dogs is 1%.
- Neurogenic keratoconjunctivitis sicca (KCS / dry eye) · Not specified in text · PO · Not specified in text · Not specified in text · Increases lacrimation. Topical ophthalmic pilocarpine can also be used for this but can be irritant.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Routes of administration
Contraindications
- Uveitis
- Anterior lens luxation
Adverse effects
- Conjunctival hyperaemia (vasodilation)
- Local ocular irritation (due to low pH)
- Salivation
- Lacrimation
- Urinary incontinence
- Gastrointestinal disturbances (vomiting, diarrhea)
- Cardiac arrhythmias
Monitoring
- Intraocular pressure (IOP) if treating glaucoma
- Schirmer tear test (STT) if treating KCS
- Signs of systemic cholinergic toxicity (SLUDGE signs: Salivation, Lacrimation, Urination, Defecation, GI upset, Emesis)
Overdose
Overdosage or systemic absorption can lead to **cholinergic toxicity** (parasympathomimetic overdrive). **Clinical signs of systemic toxicity include:** - Salivation (drooling) - Excessive lacrimation - Urinary incontinence - Gastrointestinal disturbances (vomiting, diarrhea) - Cardiac arrhythmias
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.