Correct statements about etidronate include all of the following, EXCEPT:

Correct Answer: C

Rationale: The correct answer is C because etidronate is actually a 1st generation biphosphonate, not a 2nd generation one. The skeletal half-life of etidronate is short, not hundreds of days like option A suggests. Bioavailability of etidronate decreases with the administered dose, making option B incorrect. In summary, etidronate is a 1st generation biphosphonate with a short skeletal half-life and decreasing bioavailability with higher doses.

Correct Answer: C

Rationale: The correct answer is C because aminoglycosides are known to cause ototoxicity and nephrotoxicity as unwanted effects. Ototoxicity refers to damage to the inner ear structures, leading to hearing loss or imbalance, while nephrotoxicity refers to kidney damage. Pancytopenia (choice A) is not typically associated with aminoglycosides. Hepatotoxicity (choice B) is not a common side effect of aminoglycosides. Irritation of gastrointestinal mucosa (choice D) is also not a known adverse effect of aminoglycosides.

Correct Answer: B

Rationale: The correct answer is B: Inhibition of DNA gyrase. Fluoroquinolones target DNA gyrase, an enzyme involved in bacterial DNA replication and repair. By inhibiting DNA gyrase, fluoroquinolones prevent bacterial DNA from unwinding and replicating, ultimately leading to bacterial cell death. Explanation of other choices: A: Inhibition of phospholipase C - This is incorrect as fluoroquinolones do not target phospholipase C. C: Inhibition of bacterial cell synthesis - While fluoroquinolones do affect bacterial cell synthesis indirectly by inhibiting DNA gyrase, this is not the primary mechanism of action. D: Alteration of cell membrane permeability - This is incorrect as fluoroquinolones primarily target DNA gyrase, not cell membrane permeability.

Correct Answer: C

Rationale: Interferon alfa is the correct answer as it is an endogenous protein produced by the immune system in response to viral infections. It helps to inhibit viral replication and spread. Amantadine is a synthetic antiviral drug that works by blocking viral replication. Saquinavir is a protease inhibitor used to treat HIV. Pencyclovir is an antiviral drug used to treat herpes infections. Therefore, choices A, B, and D are incorrect as they are synthetic antiviral drugs, while choice C is correct as it is an endogenous protein with antiviral properties.

Correct Answer: A

Rationale: The correct answer is A: Isosorbide mononitrate and nifedipine. Isosorbide mononitrate is a vasodilator that reduces the workload on the heart, beneficial for hypertrophic cardiomyopathy. Nifedipine is a calcium channel blocker that helps relax the heart muscle. Nitroglycerin (B and C) and captopril (B) are not commonly used in hypertrophic cardiomyopathy. Verapamil (C) can worsen symptoms in some patients with hypertrophic cardiomyopathy. Metoprolol (D) is a beta-blocker that may be used in some cases but is not as effective as nifedipine for this condition.