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.^{a b}

Uses for Homatropine

Ophthalmologic Examination

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

Ophthalmic Inflammation

Management of acute inflammatory conditions (e.g., iridocyclitis) of the uveal tract.^{a b c d}

Perioperative Mydriasis

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

Axial Lens Opacities

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

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.^{a b}

Administration

Ophthalmic Administration

Apply topically to eye(s) as an ophthalmic solution.^{a b}

For topical ophthalmic use only.^a Not for injection.^a

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

Avoid contamination of solution container.^a

Dosage

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

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

Pediatric Patients

Use only the 2% solution in pediatric patients.^{a c}

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.^{b e}

Ophthalmic Inflammation

Ophthalmic

1 drop of a 2% solution in the eye(s) 2 or 3 times daily.^{b e}

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.^{a c}

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.^{a b c}

Special Populations

No special population dosage recommendations at this time.^a

Cautions for Homatropine

Contraindications

• Known or suspected angle-closure (narrow-angle) glaucoma or a predisposition to angle-closure glaucoma.^{a b}

• Known hypersensitivity to homatropine or any ingredient in the formulation.^{a b}

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.^a

Sensitivity Reactions

Discontinue if signs or symptoms of sensitivity occur during treatment.^b

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.^{a b} Parenteral physostigmine is the recommended antidote for systemic anticholinergic symptoms.^a

Specific Populations

Pregnancy

Category C.^a

Lactation

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

Pediatric Use

Safety and efficacy not established in pediatric patients.^a

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

Geriatric Use

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

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

Common Adverse Effects

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

Homatropine Pharmacokinetics

Absorption

Bioavailability

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

Onset

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

Duration

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

Distribution

Extent

Distribution in ocular tissues not fully characterized.^c

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

Stability

Storage

Ophthalmic

Solution

Tight, light-resistant containers at 8–24°C.^{a b} Do not freeze.^b

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.^{a b}

• Produces pupillary dilation (mydriasis) and paralysis of accommodation (cycloplegia).^{a b c d}

• Cycloplegic activity is less than that of atropine.^d

• Mydriatic and cycloplegic actions are of shorter duration than those of atropine or scopolamine and of longer duration than those of cyclopentolate or tropicamide.^{b c d}

Advice to Patients

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

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

• 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.^a

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

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

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

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

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

• Importance of informing patients of other important precautionary information.^a (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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