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.

tropicamide

a rapid-acting parasympatholytic agent used topically as a mydriatic for ophthalmoscopic examination.
References in periodicals archive ?
Merelo, "A double-blind, placebo-controlled, randomized, crossover pilot study of the safety and efficacy of multiple doses of intraoral tropicamide films for the short-term relief of sialorrhea symptoms in Parkinson's disease patients," Journal of the Neurological Sciences, vol.
Groups were comprised of the tropicamide group (n = 29; 24%), the phenylephrine group (n = 29; 24%), the cyclopentolate group (n = 32; 27%), and the control group (n = 30; 25%).
DR screening in participants with an unclear view of the retina was performed after topical dilation of the pupil (using tropicamide ophthalmic solution 0.
ne percent Tropicamide eye drop and 2% Homatropine eye drops are commonly used eye drops in day to day ophthalmic practice.
Food and Drug Administration approved Paremyd eye drops which contain hydroxyamphetamine and tropicamide.
For the dilated fundus examination, we dilated the pupils with tropicamide 1.
The selective muscarinic cholinergic receptor antagonists used were: pirenzepine (Ml receptor; 10 and 100 nM); methoctramine (M2 receptor; 1 and 10 AM); N-(2-chloroethyl)-4-piperidinyl diphenylacetate N-(2-chloroethyl)-4-piperidinyl diphenylacetate (4-DAMP; M3 receptor; 10 and 100 nM); and tropicamide (M4 receptor, 1 and 10 [micro]M).
Following this examination, each participant's eyes were dilated with two sets of drops administered 5 minutes apart, each set consisting of one drop each of 1% cyclopentolate, 1% tropicamide, and 2.
5% a second placed phenylephrine atop, bandaged with 1% in place tropicamide Patterson, 1996 One pad vertical, Not stated a second horizontal, covered with tape Arbour, 1997 2 eye pads 2% taped to homatropine prevent lid from opening Antibiotic Analgesia Reference Use Use Jackson, 1960 10% sulphacetam Not stated tid(*) Hulbert, 1991 0.
The eye examination included measurement of visual acuity, intraocular pressure (with a Perkins hand-held applanation tonometer after insertion of local anaesthetic drops) [13] and slit lamp examination after pupil dilatation with 1% tropicamide.
Scinto, now at Brigham and Women's Hospital in Boston, tried one such chemical, tropicamide, on 58 individuals.