Niacin’s most common side effects can be reduced by pretreatment with aspirin and/or by taking the drug at the end of meals. This consideration is:

Correct Answer: A

Rationale: Rationale: 1. Niacin commonly causes side effects like flushing and itching due to prostaglandin release. 2. Aspirin inhibits prostaglandin synthesis, reducing niacin-induced flushing. 3. Taking niacin with meals slows absorption, minimizing side effects. 4. Therefore, pretreatment with aspirin and taking niacin at the end of meals can reduce its side effects. Summary: - Choice B is incorrect as the statement is true based on the rationale provided. - Choice C is incorrect as it implies all options are true, which is not the case. - Choice D is incorrect as the statement is true, so none of the choices are correct.

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: A

Rationale: The correct answer is A because biosynthetic penicillins are effective against a wide range of organisms listed in choice A. They work by inhibiting bacterial cell wall synthesis, making them effective against Gram-positive and some Gram-negative bacteria. Corynebacterium diphtheria, spirochetes, and Clostridium gangrene are all susceptible to penicillins. Choice B is incorrect because penicillins are not effective against mycobacterium species. Choice C is also incorrect because penicillins do not have activity against viruses. Choice D is incorrect because penicillins are not typically effective against Gram-negative cocci or Rickettsia, and they are not used for mycotic infections.

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.