USMLE Forum Archives - USMLE Step 1 - vp6
vp6
babbu5508 - 06-30-11 21:18
Which of the following medications might have precipitated this patient's condition?
/ A. AIpha2-selective agonist
/ B. Beta adrenergic antagonist
/ C. Muscarinic antagonist
/ D. Parasympathomimetic
/ E. Prostaglandin analog
babbu5508 - 06-30-11 21:18
Which of the following medications might have precipitated this patient's condition?
/ A. AIpha2-selective agonist
/ B. Beta adrenergic antagonist
/ C. Muscarinic antagonist
/ D. Parasympathomimetic
/ E. Prostaglandin analog
The correct answer and explanation will be available after you answer.
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#2
Re: vp6
babbu5508 - 06-30-11 23:04 The correct answer is C. Anticholinergics (parasympathetic antagonists) are a group of drugs that include alkaloids derived from the plant Atropa belladonna (atropine, hyoscyamine, scopolamine) and related, synthetic products (propantheline, dicyclomine, homatropine and eucatropine). They compete reversibly with acetylcholine at the level of muscarinic receptors. These agents block the cholinergic response of the ciliary muscle and the sphincter pupillae muscle, causing cycloplegia and mydriasis. Pupillary dilation causes an increased pupillary block that can precipitate acute closed-angle glaucoma in patients with occludable angles. Therefore, anticholinergics and other drugs with substantial anticholinergic activity should not be used in cases of suspected or overt glaucoma without previous gonioscopic angle evaluation.
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