Monoclonal antibodies is:

Correct Answer: D

Rationale: The correct answer is D: All of the above. Monoclonal antibodies are laboratory-produced molecules designed to target specific antigens. Trastuzumab targets HER2 protein in breast cancer, Rituximab targets CD20 antigen in B-cell lymphoma, and OKT-3 targets CD3 antigen in organ transplant rejection. Therefore, all choices A, B, and C are examples of monoclon, antibodies, making option D the correct answer. The other choices (A, B, C) are incorrect because they are individual examples of monoclonal antibodies, but the question asks for all correct options.

Correct Answer: A

Rationale: The correct answer is A: TRUE. Gemfibrozil, a fibric acid derivative, can potentiate the effects of antihypertensives leading to dizziness and syncope due to its potential to lower blood pressure. This interaction is well-documented and pharmacologically plausible. It is important to monitor patients closely when using gemfibrozil with antihypertensives to prevent adverse effects. Choices B (FALSE), C (All), and D (None) are incorrect as they do not accurately reflect the potential drug interaction between gemfibrozil and antihypertensives.

Correct Answer: D

Rationale: The correct route of administration for 1,25-dihydroxyvitamin D3 (calcitriol) is oral (Choice D). This is because calcitriol is a form of vitamin D that is typically taken orally for absorption in the intestine. When taken orally, it undergoes hepatic and renal hydroxylation to its active form. Subcutaneous (Choice A), intravenous (Choice B), and intranasal (Choice C) routes are not typically used for administering calcitriol as they may not provide the necessary absorption and metabolism required for its activation in the body.

Correct Answer: D

Rationale: Step-by-step rationale for why D (Spironolactone) is correct: 1. Spironolactone is an aldosterone receptor antagonist. 2. By competing with aldosterone for its cytosolic receptors, spironolactone inhibits its action. 3. This leads to decreased sodium reabsorption and potassium retention. 4. Spironolactone is used in conditions like heart failure, hypertension, and hyperaldosteronism. Summary of why other choices are incorrect: - A (Acetazolamide): Acts as a carbonic anhydrase inhibitor. - B (Furosemide): Inhibits the Na+/K+/2Cl- cotransporter in the loop of Henle. - C (Hydrochlorothiazide): Inhibits sodium reabsorption in the distal convoluted tubule by blocking the Na+/Cl- cotransporter.

Correct Answer: C

Rationale: Step-by-step rationale for why choice C (Aztreonam) is correct: 1. Monobactams are a class of antibiotics with a unique monocyclic beta-lactam ring structure. 2. Aztreonam is the only monobactam antibiotic listed among the choices. 3. Aztreonam is effective against aerobic Gram-negative bacteria. 4. It does not have cross-reactivity with beta-lactamases. Summary: A, B, and D are incorrect because they belong to different classes of antibiotics (penicillins, penicillin combinations, and carbapenems respectively), not monobactams.