Mydrin-P
Mydrin-P Uses, Dosage, Side Effects, Food Interaction and all others data.
Tropicamide binds to and blocks the receptors in the muscles of the eye (muscarinic receptor M4). Tropicamide acts by blocking the responses of the iris sphincter muscle to the iris and ciliary muscles to cholinergic stimulation, producing dilation of the pupil and paralysis of the ciliary muscle.
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 causes accommodation by causing 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.
| Trade Name | Mydrin-P |
| Generic | Phenylephrine Hydrochloride + Tropicamide |
| Type | |
| Therapeutic Class | |
| Manufacturer | |
| Available Country | China, Hong Kong |
| Last Updated: | September 19, 2023 at 7:00 am |
Uses
For mydriasis and cycloplegia for diagnostic procedure, for the treatment of acute and subacute iridocyclitis, chronic iridocyclitis, Adhesions and disruptions of iris and ciliary body, Sclera and iris operations
Mydrin-P is also used to associated treatment for these conditions: Diagnostic procedures
How Mydrin-P works
Muscarinic acetylcholine receptors are involved in numerous ocular functions. The M3 subtype is predominantly expressed by smooth muscle cells of the sphincter pupillae, which is a circular muscle of the iris, and ciliary muscles. In response to light or binding of acetylcholine, M3 receptor signalling leads to contraction of the sphincter pupillae and pupil constriction. Contraction of the ciliary muscle via M3 receptor signalling also leads to accommodation, adjusting the lens for near vision. The eye is also innervated by parasympathetic nerves: ciliary ganglion neurons project to the ciliary body and the sphincter pupillae muscle of the iris to control ocular accommodation and pupil constriction.
Tropicamide is a non-selective muscarinic antagonist that binds to all subtypes of muscarinic receptors. By binding to muscarinic receptors, tropicamide relaxes the pupillary sphincter muscle and causes pupil dilation. By blocking the muscarinic receptors of the ciliary body, tropicamide also prevents accommodation. Like other muscarinic antagonists, tropicamide inhibits the parasympathetic drive, allowing the sympathetic nervous system responses to dominate. Tropicamide is thought to ameliorate sialorrhea by blocking M4 receptors expressed on salivary glands and reducing hypersalivation.
Dosage
Mydrin-P dosage
For refraction:Instill one or two drops of 1% solution in the eye(s), repeated in five minutes. If patient is not seen within 20 to 30 minutes, an additional drop may be instilled to prolong mydriatic effect.
For examination of fundus:instill one or two drops of 0.5% solution 15 to 20 minutes prior to examination. Individuals with heavily pigmented irides may require higher strength or more doses.
Side Effects
Transient stinging, blurred vision, photophobia and superficial punctate keratitis have been reported with the use of tropicamide. Increased intraocular pressure has been reported following the use of mydriatics. Dryness of the mouth, tachycardia, headache, allergic reactions, nausea, vomiting, pallor, central nervous system disturbances and muscle rigidity have been reported with the use of tropicamide.
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.
Precaution
The lacrimal sac should be compressed by digital pressure for 2-3 minutes after instillation to avoid excessive systemic absorption.
Interaction
Tropicamide may interfere with the antihypertensive action of carbachol, pilocarpine, or ophthalmic cholinesterase inhibitors.
Volume of Distribution
No information can be found.
Elimination Route
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.
Half Life
Tropicamide has a plasma half-life of 30 minutes.
Clearance
No information can be found.
Elimination Route
No information can be found.
Pregnancy & Breastfeeding use
Pregnancy Category C. Tropicamide should be given to a pregnant woman only if clearly needed. It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when tropicamide is administered to a nursing woman.
Contraindication
Contraindicated in persons showing hypersensitivity to any component of Tropicamide.
Storage Condition
Store at 15° to 25°C . Do not refrigerate or store at high temperatures. Keep container tightly closed.
Innovators Monograph
You find simplified version here Mydrin-P
