The drug is the least potent diuretic:

Correct Answer: A

Rationale: The correct answer is A: Osmotic diuretics. Osmotic diuretics are the least potent diuretics as they work by creating an osmotic force that prevents water reabsorption in the nephron, leading to increased urine output. Loop diuretics (B) are more potent as they act on the ascending loop of Henle. Thiazide diuretics (C) are also more potent as they act on the distal convoluted tubule. Potassium-sparing diuretics (D) are relatively less potent than loop and thiazide diuretics but are still more potent than osmotic diuretics.

Correct Answer: B

Rationale: The correct answer is B: Headache, dizziness, insomnia. Fluoroquinolones are known to cause central nervous system side effects such as headache, dizziness, and insomnia. These unwanted effects are commonly reported with the use of fluoroquinolones. Hallucinations (choice A) are not typically associated with fluoroquinolones. Hypertension (choice C) is not a common side effect of fluoroquinolones. Immunetoxicity (choice D) is a general term and not a specific unwanted effect of fluoroquinolones. Therefore, choice B is the correct answer due to the known side effects of fluoroquinolones on the central nervous system.

Correct Answer: A

Rationale: Acyclovir is an antiviral drug used to treat herpes infections, not influenza. Amantadine and Rimantadine are anti-influenza agents that target the influenza A virus. Interferons are proteins that help the immune system fight viruses, including influenza. Therefore, the correct answer is A (Acyclovir) because it is not used specifically to treat influenza infections.

Correct Answer: C

Rationale: Rationale: 1. Digoxin inhibits Na+/K+ ATPase, leading to intracellular Na+ accumulation. 2. Increased intracellular Na+ reduces the activity of Na+/Ca2+ exchanger, causing Ca2+ to remain in the cell. 3. Elevated intracellular Ca2+ levels enhance cardiac contractility, resulting in positive inotropic effects. Summary: A: Closing of calcium channels would decrease Ca2+ influx, contrary to the inotropic effect. B: Increased release of Ca2+ from the sarcoplasmic reticulum is not the primary mechanism of digoxin's action. D: Activation of the Ca2+/Na+ exchanger would lead to Ca2+ extrusion, opposing the inotropic effect.

Correct Answer: G

Rationale: Ibutilide is the correct choice as it is a class III antiarrhythmic drug used for converting atrial fibrillation/flutter. It has a rapid onset of action and is effective in patients with normal renal function. Amiodarone (B) is a class III antiarrhythmic but is not first-line due to its potential side effects. Procainamide (C) is a class Ia antiarrhythmic and may not be suitable for this patient. Sotalol (D) is a class III antiarrhythmic but has a higher risk of proarrhythmia compared to ibutilide.