tropicamide


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Related to tropicamide: homatropine, Cyclopentolate

tropicamide

Mydriacyl® Ophthalmology An antichoinergic that blocks the action of acetylcholine, dilating the pupils in Alzheimer's disease–AD Pts in a highly diluted concentrations, a finding that some authors believe may be of use as a clinical test for AD; probably not

tropicamide

A drug used in the form of eye drops to widen (dilate) the pupil so that the inside of the eye can more easily be examined or operated upon. The drug is on the WHO official list. Brand names are Minims tropicamide and Mydriacyl.

acetylcholine (ACh) 

A neurotransmitter substance with special excitatory properties of all preganglionic autonomic neurons, all parasympathetic postganglionic neurons and a few postganglionic sympathetic neurons. Acetylcholine is synthesized and liberated by the action of the enzyme choline acetyltranferase from the compounds choline and acetyl coenzyme A (acetyl CoA) which occurs in all cholinergic neurons. ACh exists only momentarily after its formation, being hydrolysed by the enzyme acetylcholinesterase which is present in the neurons of cholinergic nerves throughout their entire lengths and at neuromuscular junctions: this process is essential for proper muscle function as otherwise the accumulation of ACh would result in continuous stimulation of the muscles, glands and central nervous system. Alternatively a shortage of ACh has devastating effect (e.g. myasthenia gravis). ACh binds to acetylcholine receptors on skeletal muscle fibres. Sodium enters the muscle fibre membrane, which leads to a depolarization of the membrane and muscle contraction. There are two main types of acetylcholine receptors (cholinergic receptors): muscarinic receptors, which are stimulated by muscarine and ACh, belong to a family of G proteins coupled receptors and are situated in parasympathetically innervated structures (e.g. the iris and ciliary body); and nicotine receptors, which are stimulated by nicotine and ACh, are ligand-gated receptors and are situated in striated muscles (e.g. the extraocular muscles). Cholinergic receptors are found in the sympathetic and parasympathetic nervous systems, in the brain and spinal cord. The action of ACh can be either blocked or stimulated by drugs: Anticholinesterase drugs (e.g. neostigmine) inhibit acetylcholinesterase and prolong the action of acetylcholine whereas antimuscarinic drugs (also referred to as anticholinergics or parasympatholytics) such as atropine, cyclopentolate, homatropine, hyoscine and tropicamide inhibit the action of acetylcholine at muscarinic receptors. Other drugs mimic the action of ACh, they are known as parasympathomimetics (e.g. pilocarpine). See cholinergic; cycloplegia; miotics; mydriatic; neurotransmitter; nicotine; synapse; autonomic nervous system.

cycloplegia 

Paralysis of the ciliary muscle resulting in a loss of accommodation. It is usually accompanied by dilatation of the pupil. See acetylcholine; anisocycloplegia; latent hyperopia; mydriatic.

mydriatic

1. Causing mydriasis of the pupil. 2. A drug which produces mydriasis. Mydriatics are used to carry out a thorough inspection of the fundus and lens, especially in elderly patients in whom the pupils are usually smaller. However, in older people it must be ascertained that the patient does not have glaucoma. There are two classes of mydriatics: (1) antimuscarinic (parasympatholytic, anticholinergic, atropine-like) drugs which antagonize the action of acetylcholine at muscarinic receptors in the ciliary muscle, such as atropine, cyclopentolate, homatropine, hyoscine (scopolamine) and tropicamide. Antimuscarinic drugs produce cycloplegia as well. (2) sympathomimetic (adrenergic stimulating) drugs which directly or indirectly stimulate the dilator pupillae muscle which is innervated by the sympathetic division of the autonomic nervous system. These include cocaine, ephedrine hydrochloride, adrenaline (epinephrine), naphazoline and phenylephrine hydrochloride. See adrenergic receptors; cholinergic; cycloplegia; miotics; dilator pupillae muscle; mydriasis; pupil light reflex; sympathomimetic.
References in periodicals archive ?
But another sports doctor told 360TV in Moscow that even a single misuse of Tropicamide, usually through the nose, can lead to blood clots.
Recreational misuse of tropicamide collyrium; early warning alerts from Russia and Italy," General Hospital Psychiatry, vol.
Rabbits were anesthetized with intramuscular injection of ketamine and xylazine, pupils were dilated with topical 1% tropicamide, and the corneas kept moist with 2.5% hydroxypropyl methylcellulose.
Pupils were dilated with 0.5% tropicamide and 0.5% phenylephrine hydrochloride.
The rats were anesthetized with isoflurane and the pupils were dilated with 0.5% tropicamide (Santen Pharmaceutical, Osaka, Japan).
in saline), the pupils were dilated by instillation of one drop of tropicamide 5%; then local anaesthesia was induced with one drop of tetracaine 1% followed by intravitreal injection of the tested compound in the right eye.
There are clinical and biologic markers available to identify the degenerative process in the brain that have been studied, such as olfactory test [4-16], pupil dilatation response to tropicamide [17-26], APOE genotype [27-34], and brain derived neurotrophic factor (BDNF) plasma level [35-42].
Retinoscopy in infant using a near non cycloplegic technique cycloplegia with tropicamide 1 % and cycloplegic with cyclopenta 1 %.
Pupils were dilated with tropicamide 1% and phenylephrine 10% eye drops.
Hypermetropes and those in whom best corrected visual acuity could not be achieved underwent cycloplegic refraction with tropicamide eye drops.
Myopia was diagnosed on the basis of eye length measurement by ultrasound imaging using E-Z Scan AB 5500+, and taking into consideration vision defect confirmed by an autorefractometer Topcon KR 9800 after paralysis of accommodation (cycloplegia) with 1% Tropicamide. All the study participants were generally healthy.
(7) We would recommend Mydriacyl [R] (tropicamide) which lasts up 6 hours.