Carbachol is a direct-acting ophthalmic miotic agent indicated to induce miosis during surgery, and to reduce the intensity of intraocular pressure (IOP) elevation in the first 24 hours after cataract surgery. Although carbachol is used exclusively as an ophthalmic preparation and extensive systemic absorption is not expected, systemic cholinergic side effects have been reported. Therefore, careful monitoring is advisable in some patient populations. Carbachol was approved by the FDA in 1972 and is available as a solution for intraocular injection.
General Administration Information
For storage information, see the specific product information within the How Supplied section.
Route-Specific Administration
Other Administration Route(s)
Intraocular Administration
Intraocular solution for injection, USP:
-Using aseptic technique, remove sterile vial from blister package by peeling the backing paper and dropping the vial onto a sterile tray.
-Withdraw the contents into a dry sterile syringe, and replace the needle with an atraumatic cannula.
-Gently instill prepared dosage into the anterior chamber.
-The solution may be instilled before or after securing sutures.
-Discard unused portion after each use; vials are single-use only.
Transient symptoms of ocular irritation, including stinging and burning, as well as blurred vision may occur commonly during ophthalmic use of carbachol. Transient ciliary injection (peripheral hyperemia of the anterior ciliary vessels), transient conjunctival hyperemia (eye redness), and ciliary body spasm with temporary decrease in visual acuity may also occur. Corneal clouding (corneal opacification), persistent bullous keratopathy, retinal detachment, and postoperative iritis following cataract extraction have been reported in association with the use of the intraocular solution. In addition, cases of corneal edema, drug associated prolonged miosis, increased intraocular pressure, ocular hyperemia, ocular inflammation, ocular pain, and visual impairment have been reported during post-marketing use of the intraocular solution. Due to the voluntary nature of post-marketing reports, neither a frequency nor a definitive causal relationship can be established.
Other systemic side effects reported with carbachol include headache, flushing, and diaphoresis (sweating). These have been reported with topical or systemic application of carbachol.
Gastrointestinal (GI) related side effects including epigastric distress and abdominal cramps (abdominal pain) have rarely been reported with topical or systemic application of carbachol. Vomiting has also been reported during the use of carbachol intraocular solution.
Carbachol intraocular solution should be used cautiously in patients with bronchial asthma. Systemic absorption of parasympathomimetic agents can result in stimulation of the mucous cells of the respiratory tract and an increase in bronchial smooth muscle tone and airway resistance, which may subsequently exacerbate some respiratory conditions.
Carbachol intraocular solution should be used cautiously in patients with active peptic ulcer disease (PUD) or gastrointestinal spasm. Systemic absorption of parasympathomimetic agents can result in increased gastric acid secretion, as well as increased GI motility and tone, which may subsequently affect gastrointestinal conditions such as PUD.
Patients at risk for retinal detachment should have periodic examinations of the retinal periphery. A thorough examination of the retina including funduscopy is advisable in all patients prior to the initiation of treatment with ophthalmic carbachol solution. As with all miotics, rare cases of retinal detachment have been reported with ophthalmic carbachol when used in certain susceptible individuals.
Carbachol intraocular solution should be used cautiously in patients with acute heart failure.
Carbachol intraocular solution should be used cautiously in patients with Parkinson's disease. Systemic absorption of cholinergic agents may result in an exacerbation of Parkinson's symptoms.
Carbachol intraocular solution should be used cautiously in patients with a urinary tract obstruction. Systemic absorption of cholinergic agents may result in stimulation of smooth muscle contractions in the bladder and ureters, potentially increasing the likelihood of complications from a urinary tract obstruction.
Carbachol intraocular solution should be used cautiously in patients with hyperthyroidism. When systemically absorbed, cholinergic agents may induce atrial fibrillation in patients with hyperthyroidism.
No adequate and well-controlled studies have been conducted with carbachol in pregnant women, and its ability to cause fetal harm or affect reproduction is unknown. The manufacturer recommends use during pregnancy only if the benefits to the mother outweigh the potential risks to the fetus. Following ophthalmic administration, carbachol is ionized at a physiologic pH and transplacental passage is not expected.
Data are limited regarding use of carbachol during breast-feeding, and its excretion into breast milk is unknown. The manufacturer advises caution when administering to nursing women. Following ophthalmic administration, clinically significant systemic concentrations are unlikely; transfer to breast-milk is not expected. To minimize the amount of drug that reaches systemic circulation, and potentially breast milk, apply pressure over the tear duct in the corner of the eye for 1 to 2 minutes after ophthalmic administration. Consider the benefits of breast-feeding, the risk of potential infant drug exposure, and the risk of an untreated or inadequately treated condition. If a breast-feeding infant experiences an adverse effect related to a maternally administered drug, health care providers are encouraged to report the adverse effect to the FDA.
Safety and efficacy of carbachol intraocular solution in neonates, infants, children, and adolescents have not been established.
Carbachol intraocular solution is contraindicated in patients who are known to be hypersensitive to the drug or any components of the product preparations. The stoppers covering the intraocular solution vials contain natural rubber; avoid use in patient with a known latex hypersensitivity.
For intraocular miosis induction during surgery and to reduce increased intraocular pressure during the first 24 hours after cataract surgery:
Intraocular dosage:
Adults: Gently instill up to 0.5 mL into the anterior chamber for the production of satisfactory miosis. The solution may be instilled before or after securing sutures. Miosis is usually maximal within 2 to 5 minutes after application.
Maximum Dosage Limits:
-Adults
Intraocular injection: 0.5 mL/dose intraocularly for induction of miosis.
-Geriatric
Intraocular injection: 0.5 mL/dose intraocularly for induction of miosis.
-Adolescents
Safety and efficacy have not been established.
-Children
Safety and efficacy have not been established.
-Infants
Safety and efficacy have not been established.
-Neonates
Safety and efficacy have not been established.
Patients with Hepatic Impairment Dosing
Specific guidelines for dosage adjustments in hepatic impairment are not available; it appears that no dosage adjustments are necessary.
Patients with Renal Impairment Dosing
Specific guidelines for dosage adjustments in renal impairment are not available; it appears that no dosage adjustments are necessary.
*non-FDA-approved indication
There are no drug interactions associated with Carbachol products.
Carbachol is a potent, direct-acting parasympathomimetic agent with muscarinic effects. Clinically, constriction of the iris and ciliary body occur, with a subsequent decrease in intraocular pressure.
Carbachol is administered via the ophthalmic route.
-Route-Specific Pharmacokinetics
Other Route(s)
Ophthalmic Route
Miosis is usually maximal within 2 to 5 minutes after application of the intraocular solution for injection. Systemic effects have been reported following topical ophthalmic or systemic application of carbachol, indicating some systemic absorption is possible.