Pilocarpine2%

Pilocarpine is a cholinergic (parasympathomimetic) agonist used in two distinct clinical settings depending on its route of administration.

Established / FDA-approved uses

• Ophthalmic (eye drops): Reduction of elevated intraocular pressure in patients with open-angle glaucoma or ocular hypertension; induction of miosis (pupil constriction), including after mydriatic eye examinations, and management of acute angle-closure glaucoma as an adjunct prior to definitive surgical treatment.
• Oral (tablets): Treatment of symptoms of dry mouth (xerostomia) caused by Sjögren's syndrome, and treatment of xerostomia caused by salivary gland hypofunction following head and neck radiotherapy.

Adjunct / combination use

• Ophthalmic Pilocarpine is often used together with, or as an adjunct to, other intraocular-pressure-lowering agents (e.g. beta-blockers, prostaglandin analogues) when a single agent does not achieve adequate control.

Pilocarpine is not indicated for uses outside these established ophthalmic and oral labeled indications.

Each formulation contains Pilocarpine Hydrochloride as the active pharmaceutical ingredient.

• Ophthalmic solution: commonly available in strengths of 1%, 2%, and 4% Pilocarpine Hydrochloride in a sterile aqueous vehicle, with preservative (e.g. benzalkonium chloride) and buffering agents.
• Oral tablets: commonly available as 5 mg film-coated tablets of Pilocarpine Hydrochloride, along with standard tablet excipients.

Pilocarpine is a direct-acting cholinergic (parasympathomimetic) agonist derived from the jaborandi plant (Pilocarpus species). It acts primarily on muscarinic acetylcholine receptors, stimulating smooth muscle contraction in the eye (iris sphincter and ciliary muscle) and secretory activity in exocrine glands, including the salivary glands.

Pilocarpine is formulated as an ophthalmic solution for topical use in the eye and as an oral tablet for systemic use in the management of dry mouth. The two formulations are used for different, non-interchangeable indications.

Pilocarpine Hydrochloride is a direct-acting muscarinic (cholinergic) receptor agonist with minimal nicotinic activity. It mimics the action of acetylcholine at muscarinic receptors on smooth muscle and exocrine gland tissue.

Ophthalmic effect

When applied topically to the eye, Pilocarpine Hydrochloride contracts the iris sphincter muscle, producing miosis, and contracts the ciliary muscle, which pulls open the trabecular meshwork and increases outflow of aqueous humor, thereby lowering intraocular pressure.

Oral (systemic) effect

When taken orally, Pilocarpine Hydrochloride stimulates muscarinic receptors on the salivary glands, increasing the secretion of saliva by exocrine glands that retain functional secretory capacity. It also stimulates other exocrine glands (sweat glands, lacrimal glands) and smooth muscle in the gastrointestinal and urinary tracts, accounting for its characteristic systemic cholinergic side effects.

Ophthalmic: Wash hands before use. Tilt the head back, pull down the lower eyelid to form a pouch, and instill the prescribed number of drops without letting the dropper tip touch the eye or any surface. Apply gentle pressure to the inner corner of the eye (nasolacrimal occlusion) for 1–2 minutes to minimize systemic absorption. If more than one eye medication is used, wait at least 5 minutes between different products.

Oral: Pilocarpine tablets should be swallowed with a glass of water, preferably with food, at evenly spaced intervals as prescribed. Do not crush or chew unless directed.

Pilocarpine has the following clinically significant drug interactions:

• Other cholinergic (parasympathomimetic) agents: Concomitant use with other cholinergic drugs (e.g. bethanechol) may produce additive cholinergic effects (excessive salivation, sweating, gastrointestinal cramping, bradycardia); avoid concurrent use unless directed by a physician.
• Beta-adrenergic blocking agents: Concurrent use of oral Pilocarpine with beta-blockers may be associated with additive effects on cardiac conduction (e.g. rare reports of conduction disturbances); use with caution and monitor.
• Anticholinergic (antimuscarinic) agents: Drugs with anticholinergic activity (e.g. atropine, many antihistamines, tricyclic antidepressants) antagonize the therapeutic effect of Pilocarpine and may reduce its efficacy.

Side effects of Pilocarpine differ by route of administration, reflecting local versus systemic cholinergic stimulation.

Ophthalmic use

• Browache and periorbital pain (very common, especially early in treatment)
• Blurred vision and dim/decreased vision at night (due to miosis)
• Local eye irritation, stinging, or redness
• Rarely, retinal detachment in predisposed individuals

Oral use

• Sweating (very common, dose-related, sometimes profuse)
• Nausea and gastrointestinal upset
• Flushing
• Increased urinary frequency
• Chills
• Headache, dizziness, and rhinitis

These effects reflect the systemic parasympathomimetic action of Pilocarpine and are usually dose-dependent; report severe or persistent symptoms to your physician.

Adequate and well-controlled studies of Pilocarpine in pregnant women are lacking. Pilocarpine should be used during pregnancy only if clearly needed and if the potential benefit justifies the potential risk to the fetus. It is not known whether Pilocarpine is excreted in human breast milk; caution should be exercised, and Pilocarpine should be used during breastfeeding only after consulting a physician regarding the benefits and risks.

Pilocarpine should be used with caution in the following situations:

• Cardiovascular disease: oral Pilocarpine can affect heart rate and cardiac conduction; use cautiously in patients with a history of cardiovascular disease.
• Controlled asthma or chronic obstructive pulmonary disease: cholinergic stimulation can increase airway resistance; use only with careful monitoring (uncontrolled asthma is a contraindication for oral use — see Contraindications).
• Biliary tract disease or nephrolithiasis: cholinergic stimulation may exacerbate smooth muscle spasm in the biliary or urinary tract.
• Cognitive or psychiatric impairment: oral Pilocarpine may impair the ability to drive or operate machinery due to visual effects or other cholinergic symptoms.
• Retinal disease: ophthalmic Pilocarpine causes miosis, which can reduce visual field and impair night vision or peripheral vision; caution advised, particularly when driving at night.
• Narrow-angle glaucoma (when using oral formulation for xerostomia): requires careful ophthalmologic assessment before use, given the differing pharmacologic context.

Pilocarpine should always be taken/used exactly as prescribed by a physician.

Overdose of Pilocarpine, particularly the oral formulation, can produce an exaggerated cholinergic (parasympathomimetic) toxidrome, including profuse sweating, salivation, nausea, vomiting, abdominal cramps, diarrhea, bradycardia, hypotension, bronchospasm, tremor, and, in severe cases, pulmonary edema or cardiovascular collapse.

If overdose is suspected, seek immediate medical attention or contact a poison control center/emergency services right away. Do not attempt to manage a suspected overdose at home. Atropine is a specific antidote and its administration should be undertaken by trained medical personnel.

Store at room temperature (below 30°C), protected from light and moisture. Keep the container tightly closed. Keep out of reach of children.

Pediatric use

The safety and efficacy of oral Pilocarpine for xerostomia have not been established in pediatric patients. Ophthalmic Pilocarpine may be used in children under close medical supervision for specific ophthalmologic indications, at the discretion of the treating physician.

Elderly patients

Elderly patients, particularly those with cardiovascular disease, should use Pilocarpine with caution given the potential for cholinergic effects on heart rate and blood pressure; dose titration and monitoring are advised.

Renal and hepatic impairment

There is limited specific dosing data for renal or hepatic impairment; Pilocarpine should be used with caution and under close medical supervision in these populations, as systemic cholinergic effects may be more pronounced.

The duration of treatment with Pilocarpine depends on the indication. For chronic glaucoma or ocular hypertension, ophthalmic Pilocarpine is typically used long-term/indefinitely to control intraocular pressure, with periodic ophthalmologic review. For xerostomia, oral Pilocarpine is generally used for as long as the underlying dry mouth symptoms persist and the physician determines continued benefit outweighs side effects; treatment should be periodically reassessed.

Cholinergic agonist (parasympathomimetic); miotic; antiglaucoma agent

Pilocarpine Hydrochloride acts directly on muscarinic acetylcholine receptors as a cholinergic agonist. In the eye, this causes contraction of the iris sphincter muscle (miosis) and the ciliary muscle, which opens the trabecular meshwork and increases aqueous humor outflow, lowering intraocular pressure. Systemically, muscarinic stimulation of exocrine glands, particularly the salivary glands, increases secretion, which underlies its use for xerostomia.

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The safety and efficacy of oral Pilocarpine in children for xerostomia have not been established, and it is not routinely recommended for pediatric use in this indication. Ophthalmic Pilocarpine may occasionally be used in pediatric patients for specific ophthalmologic conditions (e.g. diagnostic miosis) under the direct supervision of an ophthalmologist, with dosing individualized by the treating physician.