Tropicamide, like cyclopentolate, is used in ophthalmoscopy for reaching pre-operational
mydraises and for testing narrow-angle glaucoma.
일반 설명
Tropicamide, N-ethyl-2-phenyl-N-(4-pyridylmethyl)hydracrylamide (Mydriacyl), is aneffective anticholinergic for ophthalmic use when mydriasisis produced by relaxation of the sphincter muscle ofthe iris, allowing adrenergic innervation of the radial muscleto dilate the pupil. Its maximum effect is achieved inabout 20 to 25 minutes and lasts for about 20 minutes,with complete recovery in about 6 hours. Its action ismore rapid in onset and wears off more rapidly thanthat of most other mydriatics. To achieve mydriasis, either0.5% or 1.0% concentration may be used, althoughcycloplegia is achieved only with the stronger solution.Its uses are much the same as those described above formydriatics in general, but opinions differ on whether thedrug is as effective as homatropine, for example, inachieving cycloplegia. For mydriatic use, however, in examinationof the fundus and treatment of acute iritis,iridocyclitis, and keratitis, it is quite adequate; and becauseof its shorter duration of action, it is less prone toinitiate a rise in intraocular pressure than the more potent,longer-lasting drugs. As with other mydriatics, however,pupil dilation can lead to increased intraocular pressure.In common with other mydriatics, it is contraindicated inpatients with glaucoma, either known or suspected, andshould not be used in the presence of a shallow anteriorchamber. Thus far, no allergic reactions or ocular damagehas been observed with this drug. The ability to clone thevarious muscarinic receptor subtypes has allowed the observationthat tropicamide has modest selectivity for theM4 receptor.
