From the Guidelines
Tropicamide is classified as an anticholinergic mydriatic agent, specifically a muscarinic antagonist used primarily in ophthalmology. This classification is based on its mechanism of action, which involves blocking the muscarinic receptors in the eye to prevent the sphincter muscle of the iris from contracting, resulting in pupil dilation (mydriasis) and paralysis of accommodation (cycloplegia) 1.
Key Characteristics of Tropicamide
- It is commonly used during eye examinations to facilitate examination of the retina and other structures at the back of the eye.
- Tropicamide has a relatively short duration of action compared to other mydriatic agents, typically lasting 4-6 hours, which makes it preferable for routine diagnostic procedures.
- The medication is available as eye drops in concentrations of 0.5% and 1%, with the higher concentration providing more pronounced cycloplegic effects.
- When administering tropicamide, patients should be warned about temporary blurry vision, light sensitivity, and the inability to focus on near objects until the effects wear off.
Clinical Use
In clinical practice, tropicamide is often used in combination with other agents to achieve the desired level of mydriasis and cycloplegia, as seen in the study published in the journal Ophthalmology 1. The choice of tropicamide as a cycloplegic agent depends on the specific needs of the patient and the preferences of the practitioner.
Important Considerations
- A significant difference between manifest and cycloplegic refraction is observed frequently in children; in adults, a substantial difference between manifest and cycloplegic refraction is used to guide the final manifest prescription.
- The postcycloplegic refraction is performed after full accommodation has returned.
- Although most normal eyes should have a corrected acuity of 20/20 to 20/25 or better, it may not be possible to achieve this level of acuity in patients with high refractive errors, even with optimal refraction.
From the FDA Drug Label
Tropicamide Ophthalmic Solution, USP is an anticholinergic prepared as a sterile topical ophthalmic solution. The classification of Tropicamide as a class of drug is anticholinergic 2.
- Key points:
- Drug class: anticholinergic
- Specific use: ophthalmic solution
From the Research
Classification of Tropicamide
Tropicamide is classified as an antimuscarinic or anticholinergic agent, which acts as a muscarinic receptor antagonist.
- It is commonly used in ophthalmology to produce mydriasis (pupil dilation) and cycloplegia (paralysis of the ciliary muscle) 3, 4, 5, 6.
- Tropicamide is often used in combination with an alpha-adrenergic agonist, such as phenylephrine, to achieve stable mydriasis 3, 5, 6.
- The classification of Tropicamide as a muscarinic receptor antagonist is supported by its ability to bind to muscarinic receptors in the brain, although it has a low affinity for these receptors 4.
Clinical Use
- Tropicamide is used topically in the eye to dilate the pupils for various ophthalmological procedures, including electroretinography 3.
- It is also used to treat uveitis and other inflammatory conditions of the eye 7.
- The use of Tropicamide has been reported in cases of intravenous abuse, particularly in individuals with opioid use disorder 7.
Pharmacology
- Tropicamide is rapidly absorbed systemically after topical application, with peak plasma concentrations reached within 5 minutes 4.
- It has a short duration of action, with plasma concentrations decreasing rapidly over time 4.
- Tropicamide has a low incidence of systemic side effects due to its low affinity for muscarinic receptors and negligible receptor occupancy in plasma 4.