ATC Class:S01FA05

VA Class:OP600

AHFS Class:

• Mydriatics 52:24

Generic Name(s):

• Homatropine Hydrobromide

Homatropine hydrobromide, a tertiary amine antimuscarinic, is a mydriatic and cycloplegic.

Homatropine hydrobromide is used to produce mydriasis and cycloplegia for refraction and in the management of acute inflammatory conditions of the uveal tract.

Administration

Homatropine hydrobromide is applied topically to the eye in the form of a solution. To minimize drainage into the nose and throat and reduce the risk of absorption and systemic reactions, finger pressure should be applied on the lacrimal sac for 1-2 minutes following topical instillation of the solution.

Dosage

To produce mydriasis and cycloplegia for refraction in adults, 1 or 2 drops of a 2 or 5% solution may be instilled onto the eye(s) immediately before the procedure and repeated in 5-10 minutes if necessary. In children, the usual dosage to produce mydriasis and cycloplegia for refraction is 1 drop of a 2% solution instilled onto the eye(s) immediately before the procedure and repeated at 10-minute intervals as necessary.

For pupillary dilation in the treatment of acute inflammatory conditions of the uveal tract in adults, the usual dosage is 1 or 2 drops of a 2 or 5% solution instilled onto the eye(s) 2 or 3 times daily, and if necessary, as often as every 3 or 4 hours; in children, the usual dosage is 1 drop of a 2% solution 2 or 3 times daily.

Adverse Effects

Homatropine hydrobromide may increase intraocular pressure, especially in patients with glaucoma. Prolonged use of homatropine hydrobromide may cause local irritation characterized by follicular conjunctivitis, vascular congestion, edema, exudate, and eczematoid dermatitis. Systemic toxicity manifested as systemic antimuscarinic effects (see the Antimuscarinics/Antispasmodics General Statement 12:08.08) may occur, especially with frequent or prolonged topical instillation of the drug.

Precautions and Contraindications

If signs or symptoms of sensitivity occur during treatment with homatropine hydrobromide or if irritation persists or increases, patients should be advised to discontinue the drug and contact their physician.

Excessive use of homatropine hydrobromide in children or some susceptible individuals may produce adverse systemic antimuscarinic effects. Homatropine hydrobromide should be used with extreme caution in infants and young children because of increased susceptibility to the systemic effects of the drug in these patients.

Homatropine hydrobromide is contraindicated in patients with primary glaucoma or a predisposition to glaucoma. To avoid induction of angle-closure glaucoma in susceptible patients, an estimation of the depth of the angle of the anterior chamber should be made prior to the initiation of therapy. Homatropine hydrobromide is also contraindicated in patients with known hypersensitivity to the drug or any ingredient in the formulation.

Pharmacology

Following topical application to the eye, homatropine hydrobromide blocks the responses of the sphincter muscle of the iris and ciliary muscle of the lens to cholinergic stimulation, thereby producing mydriasis and cycloplegia. Homatropine hydrobromide is a relatively short-acting mydriatic and cycloplegic agent and has a shorter duration of action than atropine. The maximum mydriatic effect of homatropine hydrobromide occurs in about 10-30 minutes, and the maximum cycloplegic effect occurs in about 30-90 minutes. Mydriasis may last 6 hours to 4 days, and cycloplegia may persist 10-48 hours.

Chemistry and Stability

Chemistry

Homatropine hydrobromide is a tertiary amine antimuscarinic. The drug occurs as white crystals or a white, crystalline powder. Homatropine hydrobromide is freely soluble in water and sparingly soluble in alcohol. Commercially available ophthalmic solutions of homatropine hydrobromide have a pH of 2.5-5.

Stability

Homatropine hydrobromide is affected by light. Ophthalmic solutions of the drug should be stored in tight containers at a temperature less than 40°C, preferably between 15-30°C; freezing should be avoided.