Homatropine (Monograph)

Brand names: Homatropaire, Isopto Homatropine
Drug class: Mydriatics
ATC class: S01FA05
VA class: OP600
CAS number: 51-56-9

Introduction

Mydriatic and cycloplegic; tertiary amine antimuscarinic.

Uses for Homatropine

Ophthalmologic Examination

Used to produce mydriasis and cycloplegia for refraction. However, because homatropine has prolonged mydriatic and relatively weak cycloplegic effects, other antimuscarinics may be preferred.

Ophthalmic Inflammation

Management of acute inflammatory conditions (e.g., iridocyclitis) of the uveal tract.

Perioperative Mydriasis

Used for pre- and postoperative states when mydriasis is required.

Axial Lens Opacities

Used as an optical aid in some cases of axial lens opacities.

Homatropine Dosage and Administration

General

• Prior to initiation of therapy, estimate depth of the angle of the anterior chamber to avoid induction of angle-closure glaucoma in susceptible patients.

Administration

Ophthalmic Administration

Apply topically to eye(s) as an ophthalmic solution.

For topical ophthalmic use only. Not for injection.

Following topical application, apply finger pressure on lacrimal sac for 2–3 minutes to avoid excessive systemic absorption.

Avoid contamination of solution container.

Dosage

Available as homatropine hydrobromide; dosage expressed in terms of the salt.

In patients with heavily pigmented irides, higher dosages may be required.

Pediatric Patients

Use only the 2% solution in pediatric patients.

Ophthalmologic Examination

Ophthalmic

1 drop of a 2% solution in the eye(s) immediately before the procedure; may repeat at 10-minute intervals as necessary.

Ophthalmic Inflammation

Ophthalmic

1 drop of a 2% solution in the eye(s) 2 or 3 times daily.

Adults

Ophthalmologic Examination

Ophthalmic

1 or 2 drops of a 2 or 5% solution in the eye(s) immediately before the procedure; may repeat in 5–10 minutes if necessary.

Ophthalmic Inflammation

Ophthalmic

1 or 2 drops of a 2 or 5% solution in the eye(s) 2 or 3 times daily or, if necessary, up to every 3–4 hours.

Special Populations

No special population dosage recommendations at this time.

Cautions for Homatropine

Contraindications

• Known or suspected angle-closure (narrow-angle) glaucoma or a predisposition to angle-closure glaucoma.

• Known hypersensitivity to homatropine or any ingredient in the formulation.

Warnings/Precautions

Warnings

Concomitant Conditions

Consider risks and benefits in patients with keratoconus (homatropine may produce fixed dilated pupil), Down’s syndrome, and children with brain damage.

Sensitivity Reactions

Discontinue if signs or symptoms of sensitivity occur during treatment.

General Precautions

Systemic Effects

Excessive use, especially in children, geriatric patients, or other susceptible individuals, may produce adverse systemic antimuscarinic effects, including delirium, agitation, and coma. Parenteral physostigmine is the recommended antidote for systemic anticholinergic symptoms.

Specific Populations

Pregnancy

Category C.

Lactation

Not known whether homatropine is distributed into milk. Caution when used in nursing women.

Pediatric Use

Safety and efficacy not established in pediatric patients.

Use with extreme caution in infants and young children because of increased susceptibility to the systemic effects of the drug in these patients. Consider risks and benefits of use in children with brain damage.

Geriatric Use

No substantial differences in safety or efficacy relative to younger adults.

Use cautiously due to increased susceptibility to the systemic effects of the drug in geriatric patients.

Common Adverse Effects

Elevated IOP, transient stinging, burning. With prolonged administration, local irritation (characterized by follicular conjunctivitis, vascular congestion, edema, exudate, and eczematoid dermatitis ), thirst, dry mouth, increased light sensitivity of eyes.

Homatropine Pharmacokinetics

Absorption

Bioavailability

Following topical application to the eye, mydriatic agents are absorbed systemically, principally through the conjunctiva and nasal mucosa.

Onset

Following topical application to the eye, maximum mydriasis occurs in about 10–30 minutes, and maximum cycloplegia occurs in about 30–90 minutes.

Duration

Mydriasis may last 6 hours to 4 days, and cycloplegia persists about 10–48 hours.

Distribution

Extent

Distribution in ocular tissues not fully characterized.

Not known whether homatropine is distributed into milk after topical application to the eye.

Stability

Storage

Ophthalmic

Solution

Tight, light-resistant containers at 8–24°C. Do not freeze.

Actions

• After topical application to the eye, blocks responses of the sphincter muscle of the iris and the accommodative ciliary muscle of the ciliary body to cholinergic stimulation.

• Produces pupillary dilation (mydriasis) and paralysis of accommodation (cycloplegia).

• Cycloplegic activity is less than that of atropine.

• Mydriatic and cycloplegic actions are of shorter duration than those of atropine or scopolamine and of longer duration than those of cyclopentolate or tropicamide.

Advice to Patients

• Advise patients not to drive or engage in hazardous activities while pupils are dilated.

• Advise patients that they may experience sensitivity to light and should protect eyes in bright illumination during dilation.

• Advise parents to prevent the child from getting the solution into his or her mouth and to wash their own hands and the child’s hands following administration.

• Importance of not touching dropper tip to any surface and of learning and adhering to proper administration techniques to avoid contamination of the product.

• Importance of applying finger pressure on the lacrimal sac of the eye for 2–3 minutes following topical administration.

• Advise patients to discontinue drug and contact prescriber if signs or symptoms of sensitivity occur or if irritation persists or increases.

• Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs, as well as any concomitant illnesses.

• Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed.

• Importance of informing patients of other important precautionary information. (See Cautions.)

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name

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