The drug is usually given in combination with a thiazide diuretic:

Correct Answer: D

Rationale: The correct answer is D: Amiloride (Midamor). Amiloride is typically given in combination with a thiazide diuretic to counteract potassium loss caused by thiazides. Thiazides like Hydrochlorothiazide (Choice C) and loop diuretics like Furosemide (Choice B) can lead to hypokalemia, which is why amiloride is used to spare potassium. Acetazolamide (Choice A) is a carbonic anhydrase inhibitor and is not typically combined with thiazide diuretics for potassium-sparing effects.

Correct Answer: B

Rationale: The correct answer is B: Inhibition of DNA gyrase. Fluoroquinolones target DNA gyrase, an enzyme involved in bacterial DNA replication and repair. By inhibiting DNA gyrase, fluoroquinolones prevent bacterial DNA from unwinding and replicating, ultimately leading to bacterial cell death. Explanation of other choices: A: Inhibition of phospholipase C - This is incorrect as fluoroquinolones do not target phospholipase C. C: Inhibition of bacterial cell synthesis - While fluoroquinolones do affect bacterial cell synthesis indirectly by inhibiting DNA gyrase, this is not the primary mechanism of action. D: Alteration of cell membrane permeability - This is incorrect as fluoroquinolones primarily target DNA gyrase, not cell membrane permeability.

Correct Answer: C

Rationale: Interferon alfa is the correct answer as it is an endogenous protein produced by the immune system in response to viral infections. It helps to inhibit viral replication and spread. Amantadine is a synthetic antiviral drug that works by blocking viral replication. Saquinavir is a protease inhibitor used to treat HIV. Pencyclovir is an antiviral drug used to treat herpes infections. Therefore, choices A, B, and D are incorrect as they are synthetic antiviral drugs, while choice C is correct as it is an endogenous protein with antiviral properties.

Correct Answer: A

Rationale: The correct answer is A: Isosorbide mononitrate and nifedipine. Isosorbide mononitrate is a vasodilator that reduces the workload on the heart, beneficial for hypertrophic cardiomyopathy. Nifedipine is a calcium channel blocker that helps relax the heart muscle. Nitroglycerin (B and C) and captopril (B) are not commonly used in hypertrophic cardiomyopathy. Verapamil (C) can worsen symptoms in some patients with hypertrophic cardiomyopathy. Metoprolol (D) is a beta-blocker that may be used in some cases but is not as effective as nifedipine for this condition.

Correct Answer: C

Rationale: The correct answer is C: Quinidine. Quinidine is contraindicated due to its potential to prolong the QT interval, leading to serious arrhythmias like Torsades de Pointes. Mexiletine and Lidocaine are sodium channel blockers with lower risk of QT prolongation. Phenytoin is an anti-seizure drug and does not typically impact cardiac conduction. Therefore, Quinidine is the absolute contraindication for this patient.