Indication for etidronate administration is:

Correct Answer: B

Rationale: The correct answer is B: Paget's disease. Etidronate is a bisphosphonate used to treat Paget's disease, a condition characterized by abnormal bone remodeling leading to bone deformities and pain. It helps inhibit bone resorption and reduce the risk of fractures. A: Malabsorption of vitamin D is not an indication for etidronate, as it does not address the underlying cause of the malabsorption. C: Vitamin D deficiency is not directly treated with etidronate. Supplementation or dietary changes are more appropriate. D: Hypercalciuria is not an indication for etidronate. Etidronate is not used to manage excessive calcium excretion.

Correct Answer: D

Rationale: The correct answer is D. Tetracyclins can lead to gastrointestinal irritation, phototoxicity, hepatotoxicity, anti-anabolic effect, dental hypoplasia, and bone deformities. Gastrointestinal irritation is a common side effect due to direct irritation of the mucosa. Phototoxicity can occur upon exposure to sunlight. Hepatotoxicity refers to liver damage. Anti-anabolic effect can interfere with bone growth. Dental hypoplasia and bone deformities are associated with tetracycline use during tooth development. Choices A, B, and C only mention some of the side effects, while D encompasses all possible unwanted effects of tetracyclins.

Correct Answer: D

Rationale: The correct answer is D because all the listed effects - nausea, vomiting, allergic reactions, and hemolytic anemia - are unwanted effects associated with nitrofuranes. Nitrofuranes are known to cause gastrointestinal upset (nausea, vomiting), allergic reactions in some individuals, and hemolytic anemia, a condition where red blood cells are destroyed faster than they can be produced. Therefore, all of the above effects are unwanted and can be caused by nitrofuranes. The other choices (A, B, C) are incorrect because they do not encompass all the possible unwanted effects associated with nitrofuranes.

Correct Answer: A

Rationale: The correct answer is A: Acyclovir. Acyclovir is not an antiretroviral agent, as it is primarily used to treat herpes virus infections. Zidovudine, Zalcitabine, and Didanozine are all antiretroviral drugs used specifically to treat HIV infections. These drugs work by inhibiting the replication of the HIV virus. Acyclovir, on the other hand, works by inhibiting the replication of herpes viruses. Therefore, Acyclovir does not target HIV and is not classified as an antiretroviral agent.

Correct Answer: A

Rationale: Step 1: Isosorbide mononitrate is a nitrate that dilates blood vessels, reducing cardiac workload. Step 2: Patient likely has angina due to coronary artery disease, so vasodilation helps improve blood flow to heart. Step 3: Diltiazem, verapamil, and nifedipine are calcium channel blockers that may lower blood pressure and heart rate, but not specifically indicated for angina. Step 4: Diltiazem and verapamil can even worsen angina by reducing heart rate and contractility. Step 5: Nifedipine primarily dilates peripheral arteries and is not as effective for coronary artery vasodilation in angina.