Chloramphenicol has the following unwanted effects:

Correct Answer: B

Rationale: The correct answer is B: Pancytopenia. Chloramphenicol is known to cause bone marrow suppression, leading to a decrease in red blood cells, white blood cells, and platelets. This results in pancytopenia, which can manifest as anemia, increased risk of infections, and easy bruising or bleeding. Nephrotoxicity (A), hepatotoxicity (C), and ototoxicity (D) are not common side effects of chloramphenicol. Pancytopenia is a well-documented adverse effect of this antibiotic due to its impact on bone marrow function.

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.

Correct Answer: A

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.