A floor nurse pages you about a patient who is having chest pain. You order an electrocardiogram and rush to see the patient. He describes the pain as tight pressure and is demonstrably sweating and gasping for air. The ECG comes back with acute ST-segment elevations in inferior leads, and you diagnose a myocardial infarction. You start giving the patient oxygen and give him sublingual nitroglycerin and morphine for pain. You also give him another medication, which you have read may prolong his survival in this situation. What class of medication is it?

Correct Answer: A

Rationale: The correct answer is A: β-Blocker. β-Blockers are indicated in the management of myocardial infarction as they help reduce myocardial oxygen demand by decreasing heart rate, blood pressure, and contractility. This results in less strain on the heart muscle and can improve survival outcomes. Additionally, β-blockers can prevent arrhythmias and reduce the risk of recurrent infarction. In this scenario, where the patient is experiencing an acute myocardial infarction with ST-segment elevations, the use of a β-blocker is crucial in managing the condition and improving the patient's prognosis. Summary of other choices: B: α-Agonist - Not indicated in the management of myocardial infarction. C: Muscarinic agonist - Not indicated in the management of myocardial infarction. D: Neuromuscular blocker - Not indicated in the management of myocardial infarction.

Correct Answer: C

Rationale: Propranolol is the correct answer for migraine prophylaxis due to its beta-blocking properties, reducing sympathetic nervous system activity. This helps prevent migraine attacks. Noradrenaline and amphetamine increase sympathetic activity, exacerbating migraines. Ergotamine is used for acute migraine attacks, not prophylaxis.

Correct Answer: D

Rationale: The correct answer is D, Edrophonium, because it is not a parasympatholytic drug but rather a parasympathomimetic drug used for diagnosing myasthenia gravis. Atropine (A), Propantheline (B), and Pirenzepine (C) are all parasympatholytic drugs that inhibit the parasympathetic nervous system by blocking acetylcholine receptors. Atropine is a nonselective muscarinic receptor antagonist, Propantheline is an antimuscarinic drug used to treat gastrointestinal disorders, and Pirenzepine is a selective M1 receptor antagonist used to reduce gastric acid secretion. Therefore, D is the correct choice as it does not belong to the category of parasympatholytic drugs.

Correct Answer: D

Rationale: The correct answer is D: Haloperidol. Haloperidol is a dopamine receptor antagonist, which means it blocks dopamine receptors. Dopamine induces renal vasodilation by acting on dopamine receptors in the kidneys. Therefore, blocking these receptors with haloperidol would antagonize the renal vasodilation effect of dopamine. A: Propranolol is a beta-blocker that acts on beta receptors, not dopamine receptors. B: Atropine is a muscarinic antagonist and does not affect dopamine receptors. C: Prazosin is an alpha-1 adrenergic antagonist and does not target dopamine receptors.

Correct Answer: A

Rationale: Neostigmine is the correct choice for treating myasthenia gravis as it is an acetylcholinesterase inhibitor that increases acetylcholine levels, improving muscle strength. Pilocarpine is a muscarinic agonist used for glaucoma. Succinylcholine is a depolarizing neuromuscular blocker used for intubation. Tubocurarine is a non-depolarizing neuromuscular blocker.