Sulfonamide potency is decreased in case of co-administration with:

Correct Answer: B

Rationale: The correct answer is B: Local anesthetics – derivatives of paraaminobenzoic acid. Sulfonamides and local anesthetics both compete for the same metabolic pathway involving paraaminobenzoic acid, leading to decreased sulfonamide potency. Choices A, C, and D are incorrect because they do not interfere with the same metabolic pathway as sulfonamides, thus not affecting their potency.

Correct Answer: D

Rationale: The correct answer is D: All of the above. General contraindications for anticancer drugs include depression of bone marrow, which can lead to decreased production of blood cells; acute infections, as these drugs can further compromise the immune system; and severe hepatic and/or renal insufficiency, as these organs are responsible for drug metabolism and elimination. These contraindications are crucial to consider to prevent further harm to the patient. Choices A, B, and C individually are incorrect because they do not encompass all the general contraindications associated with anticancer drugs.

Correct Answer: C

Rationale: The correct answer is C: Procainamide. Procainamide blocks inactivated Na+ channels by binding to them preferentially when they are in the inactivated state. This mechanism helps decrease excitability in cardiac and neuronal tissues. Mexiletine (A) blocks both inactivated and activated Na+ channels, making it incorrect. Phenytoin (B) primarily blocks activated Na+ channels, not inactivated ones. Quinidine (D) blocks both inactivated and activated Na+ channels, so it is not the correct choice in this scenario.

Correct Answer: C

Rationale: The correct answer is C: Blockade of beta receptors of the vascular wall. Atenolol is a beta-blocker that works by blocking beta receptors in the vascular wall, leading to reduced sympathetic stimulation and vasodilation, ultimately lowering blood pressure. Choice A is incorrect as atenolol primarily affects beta receptors, not large veins. Choice B is incorrect as atenolol does not directly affect epinephrine release from the adrenal medulla. Choice D is incorrect as atenolol primarily acts at the beta receptors in the vascular wall rather than affecting sympathetic outflow from the vasomotor area.

Correct Answer: C

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