Class of tacrolimus (FK-506) is:

Correct Answer: B

Rationale: The correct answer is B: Immunosuppressive agents. Tacrolimus (FK-506) belongs to this class as it suppresses the immune system. It is commonly used in transplant patients to prevent organ rejection by inhibiting T-cell activation. Immunoglobulins (A) are antibodies produced by the immune system. Interferons (C) are signaling proteins released by cells in response to pathogens. Monoclonal antibodies (D) are antibodies produced by identical immune cells and used for targeted therapies. Therefore, the most appropriate classification for tacrolimus is as an immunosuppressive agent due to its mechanism of action and therapeutic use in modulating the immune response.

Correct Answer: B

Rationale: Rationale: 1. Probucol does not stimulate the rate of clearance of LDL by receptor-mediated pathways. 2. Probucol works by increasing HDL levels and reducing LDL oxidation. 3. Therefore, the statement that Probucol stimulates LDL clearance is false. 4. Choice B is correct as it accurately reflects the mechanism of action of Probucol. Summary: - Choice A is incorrect as Probucol does not stimulate LDL clearance. - Choice C is incorrect as not all statements are true. - Choice D is incorrect as the statement is false.

Correct Answer: A

Rationale: Step-by-step rationale for correct answer (A): 1. Dihydrotachysterol is a vitamin D analog used to treat parathyroid hormone resistance. 2. Parathyroid hormone resistance leads to impaired calcium absorption and bone mineralization. 3. Dihydrotachysterol helps increase calcium absorption and bone mineralization in these patients. Summary of incorrect choices: - B: Paget's disease is typically treated with bisphosphonates or calcitonin, not dihydrotachysterol. - C: Increased osteolysis is not a direct indication for dihydrotachysterol administration. - D: Hypophosphatemia is usually treated with phosphate supplements, not dihydrotachysterol.

Correct Answer: A

Rationale: Step-by-step rationale for why choice A (Hydrochlorothiazide) is correct: 1. Hydrochlorothiazide is a thiazide diuretic that decreases urine volume by increasing water reabsorption. 2. In nephrogenic diabetes insipidus, the kidneys are unable to respond to antidiuretic hormone (ADH), causing excessive urine production. 3. Hydrochlorothiazide can help reduce urine output by enhancing water reabsorption, thus alleviating symptoms of nephrogenic diabetes insipidus. Summary of other choices: - Choice B (Amiloride) is a potassium-sparing diuretic that does not directly address the underlying mechanism of nephrogenic diabetes insipidus. - Choice C (Both of the above) is incorrect as only Hydrochlorothiazide is indicated for treating nephrogenic diabetes insipidus. - Choice D (Neither of the above) is incorrect as Hydrochlorothiazide is indeed

Correct Answer: B

Rationale: The correct answer is B: Polymyxins. Polymyxins are antibiotics that work by altering the permeability of the bacterial cell membrane, leading to leakage of cellular contents and ultimately bacterial cell death. This mechanism of action is specific to polymyxins, making it the correct choice. Incorrect Choices: A: Glycopeptides - Glycopeptides work by inhibiting cell wall synthesis, not by altering cell membrane permeability. C: Tetracyclines - Tetracyclines inhibit protein synthesis in bacteria, they do not target cell membrane permeability. D: Cephalosporins - Cephalosporins interfere with cell wall synthesis, they do not directly affect cell membrane permeability.