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Pilocarpine is a drug that acts as a muscarinic receptor agonist. It acts on a subtype of muscarinic receptor (M 3) found on the iris sphincter muscle, causing the muscle to contract - resulting in pupil constriction . Pilocarpine also acts on the ciliary muscle and causes it to contract.
In 1900, Reid Hunt, a pharmacologist (1870-1948), realised a fall in blood pressure in rabbits after removing adrenaline (epinephrine) from adrenal glands extract. While he initially attributed this effect to choline, he later discovered acetylcholine was 100 000 times more potent in lowering blood pressure. [2] Sir Henry Hallett Dale
Anticholinergic drugs are used to treat a variety of conditions: Dizziness (including vertigo and motion sickness-related symptoms) Extrapyramidal symptoms, a potential side-effect of antipsychotic medications; Gastrointestinal disorders (e.g., peptic ulcers, diarrhea, pyloro spasm, diverticulitis, ulcerative colitis, nausea, and vomiting)
After instillation of cyclopentolate, pupil dilation typically lasts up to 24 hours, while paralysis of the ciliary muscle (cycloplegia) typically lasts 6-24 hours. [4] During this time, patients may be more light sensitive than normal and may notice close objects blurred (and possibly distant objects blurred, depending on the patient's visual ...
But, due to feedback regulation of the vasomotor center, there is a fall in blood pressure due to vasodilation. Important [ 5 ] muscarinic antagonists include atropine , hyoscyamine , hyoscine butylbromide and hydrobromide , ipratropium , tropicamide , cyclopentolate , pirenzepine and scopalamine .
Dilation and constriction of the pupil. Pupillary response is a physiological response that varies the size of the pupil, via the optic and oculomotor cranial nerve.. A constriction response (), [1] is the narrowing of the pupil, which may be caused by scleral buckles or drugs such as opiates/opioids or anti-hypertension medications.
Topical atropine is used as a cycloplegic, to temporarily paralyze the accommodation reflex, and as a mydriatic, to dilate the pupils. [15] Atropine degrades slowly, typically wearing off in 7 to 14 days, so it is generally used as a therapeutic mydriatic, whereas tropicamide (a shorter-acting cholinergic antagonist) or phenylephrine (an α-adrenergic agonist) is preferred as an aid to ...
Computational fluid dynamics (CFD) simulations have shown that an optimal iridotomy size to relieve the pressure differential between the anterior and posterior side of the iris is around 0.1 mm to 0.2 mm. [78] This coincides with clinical practice of LPI where an iridotomy size of 150 to 200 microns is commonly used. However, larger iriditomy ...