Unwanted effect of etidronate is:

Correct Answer: B

Rationale: The correct answer is B: Defective bone mineralization. Etidronate is a bisphosphonate used to treat osteoporosis by inhibiting bone resorption, leading to increased bone density. However, long-term use can result in defective bone mineralization, leading to brittle or weakened bones. A: Anorexia is not a known side effect of etidronate and is more commonly associated with other medications or medical conditions. C: Hypercalcemia is unlikely with etidronate use since it works to reduce calcium loss from bones. D: Cardiac arrhythmias are not a typical side effect of etidronate and are more commonly associated with other medications or underlying heart conditions.

Correct Answer: D

Rationale: The correct answer is D because Chloramphenicol is a broad-spectrum antibiotic that inhibits protein synthesis in bacteria, making it bacteriostatic. It affects both Gram-positive and Gram-negative microorganisms. Choice A is incorrect because chloramphenicol is bacteriostatic, not bactericidal. Choice B is incorrect because it influences both Gram-positive and Gram-negative bacteria. Choice C is incorrect because it also influences both types of bacteria and it is bacteriostatic, not bactericidal.

Correct Answer: D

Rationale: The correct answer is D because fluoroquinolones are broad-spectrum antibiotics effective against a variety of Gram-negative and Gram-positive microorganisms, including Mycoplasmas and Chlamydiae. Fluoroquinolones work by targeting bacterial DNA gyrase and topoisomerase IV, which are essential for DNA replication. This mechanism of action allows fluoroquinolones to inhibit the growth of a wide range of bacteria. Choices A, B, and C are incorrect because fluoroquinolones are not limited to only Gram-negative or Gram-positive microorganisms, but rather have activity against both types of bacteria, making them effective against a diverse range of pathogens.

Correct Answer: A

Rationale: The correct answer is A: Didanosine. Nucleoside reverse transcriptase inhibitors (NRTIs) are a class of antiretroviral drugs used to treat HIV/AIDS. Didanosine is an NRTI that inhibits the reverse transcriptase enzyme, crucial for HIV replication. Gancyclovir is a nucleoside analog used to treat viral infections but not specifically NRTIs. Nevirapine is a non-nucleoside reverse transcriptase inhibitor. Vidarabine is a nucleoside analog antiviral drug, but it is not classified as an NRTI. Overall, only Didanosine belongs to the NRTI class of drugs.

Correct Answer: C

Rationale: The correct answer is C: Decreased myocardial remodeling. Beta-blockers decrease the workload of the heart by reducing heart rate and contractility, which in turn decreases myocardial oxygen demand and reduces the risk of further damage to the heart muscle post-myocardial infarction. This leads to a decrease in adverse remodeling of the heart, improving overall cardiac function and reducing mortality. Incorrect Choices: A: Increased myocardial oxygen supply - Beta-blockers do not directly increase myocardial oxygen supply but rather decrease oxygen demand. B: Decreased atrioventricular conduction - While beta-blockers can slow atrioventricular conduction, this is not the primary mechanism for mortality reduction in myocardial infarction. D: Increased systemic vascular resistance - Beta-blockers actually decrease systemic vascular resistance, which can be beneficial in certain conditions but is not the primary reason for mortality reduction in myocardial infarction.