The drug should never be administered to patients taking potassium supplements:

Correct Answer: B

Rationale: The correct answer is B: Amiloride (Midamor). Amiloride is a potassium-sparing diuretic that helps the body retain potassium. Administering it to patients already taking potassium supplements can lead to hyperkalemia, an excessive level of potassium in the blood, which can be dangerous. Hydrochlorothiazide (A) and Furosemide (C) are not potassium-sparing diuretics and do not pose the same risk of hyperkalemia. Choice D is incorrect because Amiloride specifically interacts with potassium levels, making it crucial to avoid concurrent use with potassium supplements.

Correct Answer: B

Rationale: The correct answer is B: Inhibition of folate synthesis. Aminosalicylic acid acts by inhibiting the enzyme dihydropteroate synthase in the folate synthesis pathway of bacteria. This disrupts the production of essential folate cofactors needed for DNA and RNA synthesis, ultimately leading to bacterial growth inhibition. Incorrect choices: A: Inhibition of mycolic acids synthesis - This mechanism is associated with drugs like isoniazid in the treatment of mycobacterial infections. C: Inhibition of DNA dependent RNA polymerase - This mechanism is associated with drugs like rifampin. D: Inhibition of DNA gyrase - This mechanism is associated with drugs like fluoroquinolones.

Correct Answer: C

Rationale: The correct answer is C: Saquinavir. Saquinavir is a protease inhibitor, not a nucleoside analog. Nucleoside analogs (A, B, D) mimic nucleosides and interfere with viral replication by inhibiting DNA or RNA synthesis. Acyclovir (A) is used for herpes viruses, Zidovudine (B) for HIV, Didanosine (D) for HIV. Saquinavir (C) inhibits protease enzyme in HIV, preventing viral maturation.

Correct Answer: D

Rationale: The correct answer is D: Epinephrine. Epinephrine is a vasopressor and bronchodilator used in emergency situations like dyspnea to improve breathing and increase blood pressure. Hydrochlorothiazide and Amiloride are diuretics used to treat hypertension and edema, not acute dyspnea. Mannitol is an osmotic diuretic used to reduce intracranial pressure, not for dyspnea. Epinephrine is the most appropriate choice for immediate relief of dyspnea due to its bronchodilator effects and ability to improve breathing quickly.

Correct Answer: B

Rationale: The correct answer is B: Blockade of Na+ channels in the collecting duct. This action prevents Na+ reabsorption, leading to increased Na+ in the urine and decreased K+ secretion. This mechanism is seen in potassium-sparing diuretics like amiloride and triamterene. Choices A and C do not directly impact potassium sparing. Choice D is incorrect as aldosterone receptor blockade would lead to increased K+ excretion.