Tropicamide

BRAND NAMES:

Mydriacyl: It is available in ophthalmic solutions with strengths of 0.5% and 1.0% solutions. It’s main active ingredient tropicamide.

Paremyd: Paremyd sterile ophthalmic solution is a topical mydriatic combination product for ophthalmic use. It’s main active ingredients hydroxyamphetamine hydrobromide 1.0% and tropicamide 0.25%

MECHANISM OF ACTION:

Mechanism for Dilation:

Tropicamide, a parasympathetic antagonist, relaxes and dilates the pupillary sphincter muscle. Tropicamide, like other anticholinergic medications, reduces the parasympathetic drive and allows sympathetic reactions to gain primacy. The sympathetic nervous system innervates the radial muscles of the iris (dilator pupillae), which contract to dilate the pupil. Its maximum influence comes 25 to 30 minutes after consumption. Typically, mydriasis disappears in 4 to 8 hours. Some people may have a mydriatic effect that lasts up to 24 hours. Weakness may develop in mydriasis with little cycloplegia.

Mechanism for cycloplegia:

Tropicamide inhibits accommodation by blocking the ciliary body's muscarinic receptors. Its cycloplegic impact can last anywhere from 4 to 10 hours, with activity beginning in 20 to 30 minutes. This reduces nearsightedness.

Mechanism for reduction of sialorrhea:

The inhibition of muscarinic acetylcholine receptors on salivary glands is responsible for lowering hypersalivation in Parkinson's disease patients. Its potential therapeutic usefulness stems from its relatively high selectivity for M4 receptors. Researchers have shown good outcomes in eliminating drug-induced tremulous jaw movement in animal models. Future research will be needed to discover whether the tremorolytic effects can be therapeutically used and extended to humans.

PHARMACODYNAMICS:

Tropicamide is an anticholinergic medication that blocks muscarinic receptors, causing mydrasis and cycloplegia. It relaxes the pupillary sphincter, causing the pupil to widen. The beginning of tropicamide-induced mydriasis is 10 to 15 minutes, with the optimal impact happening 25 to 30 minutes after treatment. Tropiamide-induced mydriasis usually resolves within four to eight hours, although it might last up to 24 hours in certain cases. Tropicamide inhibits accommodation by contracting the ciliary muscle. The cycloplegic effect begins within 20 to 30 minutes of treatment and lasts four to 10 hours. Tropicamide can cause increased intraocular pressure. Tropiamide's ophthalmic usage is seldom linked with significant systemic adverse effects.

DOSAGE AND ADMINISTRATION:

The administration necessitates the removal of contact lenses. This topical ophthalmic solution is put into the eye as droplets. To minimize systemic absorption and undesirable effects, squeeze the lacrimal sac with a fingertip for 2 to 3 minutes following delivery. The dropper tip should not come into contact with any surface, since this might contaminate the medicine. In a youngster, make sure the medicine does not enter their mouth. Hands must be washed before and after infusing the drop. During pupillary dilatation, the individual should avoid driving and other potentially dangerous activities. Following pupillary dilatation, light sensitivity may develop, necessitating sunglasses.

Spray application is a less common approach. Several investigations have demonstrated that tropicamide in its vaporized form is as efficient in increasing pupil diameter while causing less patient pain. In a randomized clinical study, researchers determined that administering Mydriasert (5.4 mg phenylephrine hydrochloride and 0.28 mg tropicamide) via an ocular insert was safe and efficacious in newborns.

CONTRAINDICATIONS:

Hypersensitivity to any active or inactive component is a contraindication for its use. There has been no study on tropicamide use in nursing. However, nursing mothers can reduce the amount that enters the nasolacrimal duct by applying pressure to the lacrimal sac and wiping away any excess solution.

DRUG INTERACTIONS:

Tropicamide may interact with medications, including

• Respiratory conditions: diphenhydramine
• Motion sickness: meclizine
• Irritable bowel syndrome: dicyclomine
• Parkinson's disease: selegiline
• Antibiotics: linezolid
• Chemotherapeutic agents: methylene blue
• Antidepressants: tranylcypromine and phenelzine 

SIDE EFFECTS:

The common side effects of tropicamide include

• Blurred vision
• headache
• dry mouth
• Agitation
• Change in vision
• Mild stinging of eyes
• Dry mouth
• Irregular heartbeat
• Difficulty breathing

TOXICITY:

Although tropicamide is a short-acting drug with a low frequency of adverse events, there are times when reversing mydriasis is necessary, such as to reduce the risk of angle-closure glaucoma, improve blurry vision, and shorten recovery time for patient comfort. A cholinergic agent such as pilocarpine should be able to counteract the effects of an anticholinergic medication. However, multiple investigations have shown contradictory pupillary responses. Using dapiprazole can reduce the recovery time in half compared to waiting for tropicamide to wear off. Unfortunately, the FDA removed dapiprazole from the market for reasons unrelated to safety and efficacy. Currently, there are no approved therapies for tropicamide-induced mydriasis; thus, patients should use sunglasses to lessen light sensitivity.