This fibric acid derivative increases blood levels of high density lipoproteins (HDL):

Correct Answer: C

Rationale: Step-by-step rationale for why Choice C: Gemfibrozil (Loprol) is correct: 1. Gemfibrozil is a fibric acid derivative known to increase HDL levels. 2. It works by activating lipoprotein lipase, which increases the breakdown of triglycerides and raises HDL levels. 3. Cholestyramine (A) is a bile acid sequestrant that does not affect HDL levels. 4. Lovastatin (B) is a statin that primarily lowers LDL levels. 5. Probucol (D) is an antioxidant that mainly lowers LDL levels and does not significantly impact HDL levels.

Correct Answer: B

Rationale: Step 1: Furosemide is a loop diuretic, which acts on the ascending loop of Henle to inhibit sodium and chloride reabsorption, leading to potent diuresis. Step 2: Loop diuretics like Furosemide are more potent compared to other diuretics like thiazides (Hydrochlorothiazide) or potassium-sparing diuretics (Amiloride). Step 3: Acetazolamide is a carbonic anhydrase inhibitor that works in the proximal tubule and has a different mechanism of action, making it less potent than loop diuretics. Step 4: Therefore, the correct answer is B, Furosemide, as it is a potent diuretic acting on the loop of Henle. Other choices are less potent due to their mechanisms of action and sites of action.

Correct Answer: D

Rationale: Step-by-step rationale for Answer D being correct: 1. Aminoglycosides are primarily effective against aerobic Gram-negative bacteria. 2. They are broad-spectrum antibiotics but not effective against anaerobic microorganisms. 3. Aminoglycosides do not have antiviral properties. 4. Therefore, Answer D is correct as it accurately states their spectrum of activity. Summary of why other choices are incorrect: A: Incorrect because aminoglycosides are not effective against Gram-positive microorganisms, anaerobic microorganisms, or spirochetes. B: Incorrect because aminoglycosides are not effective against Pseudomonas aeruginosa. C: Incorrect because aminoglycosides are primarily effective against aerobic Gram-negative bacteria, not anaerobic microorganisms.

Correct Answer: A

Rationale: The correct answer is A because nausea, vomiting, diarrhea, and stomatitis are common side effects of Metronidazole. Hypertension and disturbances of peripheral blood circulation are not typically associated with Metronidazole use. Therefore, choice A is the only option that accurately reflects the unwanted effects of Metronidazole.

Correct Answer: B

Rationale: The correct answer is B: Zidovudine. Zidovudine is a nucleoside analog reverse transcriptase inhibitor used in the treatment of HIV infection. It works by inhibiting the reverse transcriptase enzyme, crucial for viral replication. Acyclovir (A) is used for herpes infections, Gancyclovir (C) for cytomegalovirus, and Trifluridine (D) for ocular herpes. They are not derivatives of nucleosides and are not used for HIV treatment.