Created by Andrew Street
about 8 years ago
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Question | Answer |
Give eg's of & indications for cardiovascular & GI antimuscarinics. | eg's: atropine, hyoscine butylbromide, glycopyrronium Indications: • Bradycardia - atropine is 1st line Rx to manage severe or symptomatic bradycardia • IBS (especially hyoscine butylbromide) - 1st line pharmacological Rx • To reduce copious respiratory secretions in the dying pt (hyoscine butylbromide) |
MOA of cardiovascular & GI antimuscarinics. | Antimuscarinic drugs bind to the muscarinic receptor, where they act as a competitive inhibitor of acetylcholine. Stimulation of the muscarinic receptor brings about a wide range of parasympathetic ‘rest & digest’ effects. In blocking the receptor, antimuscarinics have the opposite effects: they ^HR & conduction; reduce smooth muscle tone & peristaltic contraction, including in the gut & urinary tract; & reduce secretions from glands in the respiratory tract & gut. In the eye they cause relaxation of the pupillary constrictor & ciliary muscles, causing pupillary dilatation & preventing accommodation, respectively. |
SE's of cardiovascular & GI antimuscarinics. | • Tachycardia • Dry mouth • Constipation • Urinary retention (reduction in detrusor muscle activity) • Blurred vision • Some antimuscarinics (including atropine) have central effects, which may precipitate drowsiness & confusion, particularly in the elderly |
CI's, cautions, & important interactions of cardiovascular & GI antimuscarinics. | CI's: • Avoid in pt's at risk of arrhythmias (eg those with significant cardiac DS) unless the indication for use is bradycardia Cautions: • Angle-closure glaucoma - can precipitate a dangerous rise in intraocular pressure Important interactions: Adverse effects are more pronounced when they are combined with other drugs that have antimuscarinic effects, such as tricyclic antidepressants. |
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