Which of the following agents exerts its therapeutic effect in multiple sclerosis via potassium channel blockade?

Correct Answer: A

Rationale: Dalfampridine treats MS by blocking potassium channels in demyelinated axons, enhancing nerve conduction and improving walking ability. Exposed potassium channels in MS leak current, impairing signal propagation; dalfampridine's blockade restores function. Donepezil boosts acetylcholine for Alzheimer's. Riluzole reduces glutamate in ALS. Bromocriptine, a dopamine agonist, manages Parkinson's. Dalfampridine's unique potassium channel action directly addresses MS's neurological deficit, supported by clinical evidence, making it the correct agent here.

Correct Answer: A

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

Correct Answer: B

Rationale: Hydralazine, a vasodilator, lowers blood pressure but triggers reflex tachycardia. A heart rate of 110 bpm indicates significant compensation, risking ischemia or strain, requiring immediate action (e.g., slowing infusion, notifying physician). BP of 140/90 is improved, not critical. Headache and flushing are expected from vasodilation, less urgent. Tachycardia's potential to destabilize circulation, especially in severe hypertension, aligns with hydralazine's pharmacology'arteriolar relaxation prompts sympathetic response. This finding demands swift intervention to prevent cardiovascular collapse, making B the priority over manageable side effects.

Correct Answer: D

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