tropicamida

Tropicamida, commonly known as tropicamide in English, is a short-acting antimuscarinic drug used in ophthalmology to induce pupil dilation (mydriasis) and cycloplegia for eye examinations and procedures. In some languages the name tropicamida is used, but the English-formulation remains tropicamide. It is typically applied as a topical eye drop.

Tropicamide works by blocking muscarinic acetylcholine receptors in the iris sphincter muscle and ciliary body, preventing pupillary constriction and accommodation. This leads to dilation of the pupil and loss of the ability to focus on close objects for several hours.

The drug is usually administered as a 0.5% or 1% ophthalmic solution. Onset of mydriasis is generally within 20 to 60 minutes, with the dilation lasting about 4 to 6 hours and cycloplegia often persisting for 6 to 24 hours, depending on the individual and the formulation. It is commonly used alone or in combination with a sympathomimetic agent such as phenylephrine to enhance dilation in diagnostic examinations or preoperative settings.

Safety and precautions: Tropicamide is generally well tolerated but can cause local eye irritation, blurred vision, or light sensitivity. Systemic anticholinergic effects are rare with topical use but may occur in cases of overdose or inadvertent ingestion. It is contraindicated in individuals with known hypersensitivity to tropicamide or with narrow-angle glaucoma where dilation could precipitate an attack. Caution is advised when used with other anticholinergic drugs or medications influencing heart rate or blood pressure.

See also: atropine, cyclopentolate, mydriatics, cycloplegics.