Which of the following statements refers to etidronate:

Correct Answer: A

Rationale: Step-by-step rationale for why choice A is correct: 1. Etidronate is a biphosphonate drug used to reduce osteoclast activity in conditions like Paget's disease. 2. It inhibits bone resorption by osteoclasts without significantly affecting osteoblasts. 3. Monitoring serum phosphorus levels daily (choice B) is not necessary for etidronate. 4. Etidronate is a first-generation biphosphonate, not a 2nd generation (choice C). 5. Bioavailability of etidronate is poor and decreases with increasing doses, so choice D is incorrect.

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.

Correct Answer: A

Rationale: The correct answer is A: Verapamil. Verapamil is a calcium channel blocker that can help prevent delayed cerebral ischemia by reducing vasospasm in the blood vessels in the brain. This is important in patients with blood in the subarachnoid space, as vasospasm can lead to decreased blood flow and subsequent ischemia. Isosorbide mononitrate (B) and Propranolol (C) are not typically used for preventing cerebral vasospasm. Dobutamine (D) is a positive inotrope and is not indicated for preventing cerebral vasospasm.