Tropicamide

Absorption

Following ocular administration of 40 μL drops of 0.5% tropicamide in female subjects, tropicamide reached its mean peak concentration in plasma of 2.8 ± 1.7 ng/mL (mean ± SD) at five minutes.

Toxicity

Oral LD50 is 865 mg/kg in rats and 565 mg/kg in mice. Intraperitoneal LD50 is 1210 mg/kg in rats and 695 mg/kg in mice. Subcutaneous LD50 is 872 mg/kg in rats and 665 mg/kg in mice.
There is limited information on tropicamide overdose. Systemic adverse effects, such as tachycardia, central nervous system disturbances, and muscle rigidity have been reported with the use of tropicamide. Psychotic reactions, behavioral disturbances, and vasomotor or cardio-respiratory collapse have been reported with the use of anticholinergic in children.

The Uses of Tropicamide

Tropicamide, like cyclopentolate, is used in ophthalmoscopy for reaching pre-operational mydraises and for testing narrow-angle glaucoma.

Indications

Tropicamide is indicated to induce mydriasis (dilation of the pupil) for diagnostic procedures and in conditions where short-term pupil dilation is desired, either as monotherapy or in combination with hydroxyamphetamine or phenylephrine. It provides clinically significant mydriasis with partial cycloplegia.

Background

Tropicamide is an alkaloid atropine‐derived anticholinergic drug and a non‐selective antagonist of muscarinic acetylcholine (mACh) receptors. Usually available in ophthalmic formulations, tropicamide is used to cause mydriasis and cycloplegia for eye exams or ocular procedures. It is also used in combination with hydroxyamphetamine for the same indication. Oral tropicamide has been investigated as a potential drug to relieve sialorrhea in patients with Parkinson's Disease.

What are the applications of Application

Tropicamide is a mAChR M4 antagonist

Pharmacokinetics

Tropicamide is an anticholinergic drug and that works by non‐selectively blocking muscarinic receptors to cause mydriasis and cycloplegia. It relaxes the pupillary sphincter to dilate the pupil. The onset of tropicamide‐induced mydriasis is about 10 to 15 minutes, with optimal effect occurring 25 to 30 minutes post-administration. Mydriasis caused by tropicamide wears off within four to eight hours, but it was seen up to 24 hours in some individuals. Tropicamide hinders accommodation by causing the contraction of the ciliary muscle. The cycloplegic effect occurs within 20 to minutes following administration, with a duration of action of four to 10 hours. Tropicamide can elevate intraocular pressure. The ophthalmic use of tropicamide is not typically associated with serious systemic adverse events.
One randomized pilot study showed that oral tropicamide alleviated perceived symptoms of sialorrhea in patients with Parkinson's Disease: anticholinergics are believed to restore the dopaminergic to cholinergic activity imbalance in neurodegenerative diseases. Similarly in one case report, tropicamide administered via ophthalmic solution relieved clozapine-induced sialorrhea. Interestingly, in rodent models, tropicamide suppressed drug-induced tremulous jaw movements which are often used as a model of parkinsonian tremor: the significance of this finding requires further investigations.

Metabolism

No information can be found.