PILOCARPINE HYDROCHLORIDE

PILOCARPINE HYDROCHLORIDE
PILOCARPINE NITRATE
(pye-loe-kar'peen)
Adsorbocarpine, Isopto Carpine, Minims Pilocarpine , Miocarpine , Ocusert, Pilo, Pilocar, Salagen
Classifications: eye preparation; miotic (antiglaucoma agent); direct-acting cholinergic;
Therapeutic: antiglaucoma

Pregnancy Category: C

Availability

0.25%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 8%, 10% ophthalmic solution; 4% ophthalmic gel; 20 mcg/h, 40 mcg/h ocular insert; 5 mg tablets

Action

In open-angle glaucoma, pilocarpine causes contraction of the ciliary muscle, increasing the outflow of aqueous humor. This reduces intraocular pressure (IOP). In closed-angle glaucoma, it induces miosis by opening the angle of the anterior chamber of the eye, through which aqueous humor exits.

Therapeutic Effect

Decrease in IOP results from stimulation of ciliary and papillary sphincter muscles, which pull iris away from filtration angle, thus facilitating outflow of aqueous humor. Pilocarpine also decreases production of aqueous humor.

Uses

Open-angle and angle-closure glaucomas; to reduce IOP and to protect the lens during surgery and laser iridotomy; to counteract effects of mydriatics and cycloplegics following surgery or ophthalmoscopic examination; to treat xerostomia.

Contraindications

Secondary glaucoma, acute iritis, acute inflammatory disease of anterior segment of eye; asthma; pregnancy (category C), lactation. Ocular therapeutic system: Not used in acute infectious conjunctivitis, keratitis, retinal detachment, or when intense miosis is required, contact lens.

Cautious Use

Bronchial asthma; biliary tract disease; COPD; hypertension.

Route & Dosage

Acute Glaucoma
Adult/Child: Ophthalmic 1 drop of 1–2% solution in affected eye q5–10min for 3–6 doses, then 1 drop q1–3h until IOP is reduced

Chronic Glaucoma
Adult/Child: Ophthalmic 1 drop of 0.5–4% solution in affected eye q4–12h or 1 ocular system (Ocusert) q7d

Miotic
Adult/Child: Ophthalmic 1 drop of 1% solution in affected eye

Xerostomia
Adult: PO 5 mg t.i.d., may increase up to 10 mg t.i.d.

Administration

Instillation
  • Note: During acute phase, physician may prescribe instillation of drug into unaffected eye to prevent bilateral attack of acute glaucoma.
  • Apply gentle digital pressure to periphery of nasolacrimal drainage system for 1–2 min immediately after instillation of drops to prevent delivery of drug to nasal mucosa and general circulation.

Adverse Effects (≥1%)

CNS: Oral (asthenia, headaches, dizziness, chills). Special Senses: Ciliary spasm with brow ache, twitching of eyelids, eye pain with change in eye focus, miosis, diminished vision in poorly illuminated areas, blurred vision, reduced visual acuity, sensitivity, contact allergy, lacrimation, follicular conjunctivitis, conjunctival irritation, cataract, retinal detachment. GI: Nausea, vomiting, abdominal cramps, diarrhea, epigastric distress, salivation. Respiratory: Bronchospasm, rhinitis. CV: Tachycardia. Body as a Whole: Tremors, increased sweating, urinary frequency.

Interactions

Drug: The actions of pilocarpine and carbachol are additive when used concomitantly. Oral form may cause conduction disturbances with beta blockers. Antagonizes the effects of concurrent anticholinergic drugs (e.g., atropine, ipratropium). Food: High-fat meal decreases absorption of pilocarpine.

Pharmacokinetics

Absorption: Topical penetrates cornea rapidly; readily absorbed from GI tract. Onset: Miosis 10–30 min; IOP reduction 60 min; salivary stimulation 20 min. Peak: Miosis 30 min; IOP reduction 75 min; salivary stimulation 60 min. Duration: Miosis 4–8 h; IOP reduction 4–14 h (7 d with Ocusert); salivary stimulation 3–5 h. Metabolism: Inactivated at neuronal synapses and in plasma. Elimination: In urine. Half-Life: 0.76–1.35 h.

Nursing Implications

Assessment & Drug Effects

  • Be aware that hourly tonometric tests may be done during early treatment because drug may cause an initial transitory increase in IOP.
  • Monitor changes in visual acuity.
  • Monitor for adverse effects. Brow pain and myopia tend to be more prominent in younger patients and generally disappear with continued use of drug.

Patient & Family Education

  • Understand that therapy for glaucoma is prolonged and that adherence to established regimen is crucial to prevent blindness.
  • Do not drive or engage in potentially hazardous activities until vision clears. Drug causes blurred vision and difficulty in focusing.
  • Discontinue medication if symptoms of irritation or sensitization persist and report to physician.

Ocular Therapeutic System (Ocusert)

  • Review information/directions about inserting the ocular system included in the drug package with health care provider. Demonstrate to establish ability to adjust, insert, and remove the system.
  • Unit is placed in the eye cul-de-sac, where it remains for a week. Slow release of drug provides a nonfluctuating concentration of pilocarpine in the ciliary body and iris.
  • Induced myopia, miosis, and spasm of accommodation are less than that produced by eyedrops. However, since transient blurring and dimness of vision may occur following Ocusert insertion, have patient do so at bedtime; myopia will be at a stable level in the a.m.
  • Several hours after Ocusert insertion, induced myopia decreases to a low base level that persists for the life of the therapeutic system.
  • Notify physician if following symptoms do not subside: Conjunctival irritation with mild erythema and increase in mucus secretion; generally accompany early use of Ocusert.
  • Wash system with cool tap water before replacing it into cul-de-sac if it contacts an unclean surface.
  • If retention of the system is a problem, the superior conjunctival cul-de-sac may be a preferred site for insertion. This location is also preferred during sleep.
  • To change placement: Ocusert may be transferred from the lower conjunctival sac to the superior sac by closing eyelids, rolling the eye toward the nose and, with gentle digital pressure through the closed eyelid, directly moving the system. Avoid moving it over the colored part of the eye.
  • Remove system and replace with a new one if an unexpected increase in drug action occurs (sudden miosis, ciliary spasm, decreased visual acuity).

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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