A drug ending in the suffix (navir) is considered a ______.

Correct Answer: B

Rationale: The correct answer is B: Protease inhibitor. Drugs ending in the suffix (navir) are commonly used to inhibit protease enzymes in viruses, particularly in the treatment of HIV/AIDS. Protease inhibitors disrupt viral replication by preventing the cleavage of viral proteins, thus inhibiting the production of new infectious viral particles. Choice A, Antidepressant, is incorrect as drugs used to treat depression usually end in (ine) or (pram). Choice C, Beta antagonist, is incorrect as drugs affecting beta receptors typically end in (olol) or (lol). Choice D, H antagonist, is incorrect as drugs targeting histamine receptors usually end in (ine) or (idine).

Correct Answer: B

Rationale: The correct answer is B: Hypotension. Prednisone toxicity typically causes hypertension, not hypotension. Prednisone can lead to increased blood pressure due to its sodium-retaining effects. Cataracts (A), Psychosis (C), and Acne (D) are all known side effects of Prednisone toxicity. Cataracts can form due to long-term steroid use, psychosis can occur especially at higher doses, and acne is a common skin side effect. Therefore, hypotension is the odd one out among the choices given.

Correct Answer: B

Rationale: The correct answer is B: Tachycardia. Atenolol is a beta-blocker that works by slowing down the heart rate, so tachycardia is not related to its toxicity. A: CHF can be exacerbated by Atenolol due to its negative inotropic effects. C: AV block can occur as Atenolol can further slow down the heart's conduction system. D: Sedative appearance can be a side effect of Atenolol due to its action on the central nervous system. In summary, tachycardia is not related to Atenolol toxicity because it decreases heart rate.

Correct Answer: D

Rationale: The correct answer is D: Procainamide. Procainamide is a class IA antiarrhythmic drug that blocks sodium channels, prolonging the action potential duration. This helps to stabilize the heart's rhythm. Mexiletine (A) is a class IB antiarrhythmic drug that blocks sodium channels with fast recovery kinetics. Amiodarone (B) is a class III antiarrhythmic drug that prolongs repolarization by blocking potassium channels. Quinidine (C) is a class IA antiarrhythmic drug that also blocks sodium channels, but it is not a class IB sodium channel blocker like Procainamide.

Correct Answer: A

Rationale: The correct answer is A: Quinidine. Quinidine is a class IA antiarrhythmic drug that blocks sodium channels in a use-dependent manner, which means it preferentially blocks channels that are open or have a rapid firing rate during depolarization. This action results in a decrease in conduction velocity and refractory period. Disopyramide is a class IA antiarrhythmic but does not specifically block sodium channels. Amiodarone is a class III antiarrhythmic that primarily affects potassium channels. Propafenone is a class IC antiarrhythmic that has minimal effects on sodium channel blockade. Therefore, Quinidine is the correct choice as a class IA sodium channel blocker.