Which of the following substances is a vitamin-like compound?

Correct Answer: B

Rationale: Step 1: Taurine is a vitamin-like compound as it is an amino acid that has functions similar to vitamins in the body. Step 2: Ascorbic acid (Vitamin C) is a vitamin, not a vitamin-like compound. Step 3: Thiamine (Vitamin B1) and Riboflavin (Vitamin B2) are both vitamins, not vitamin-like compounds. Summary: Taurine is the correct answer as it is an amino acid with functions similar to vitamins, while the other choices are known vitamins.

Correct Answer: B

Rationale: Step-by-step rationale: 1. Dihydrotachysterol is a form of vitamin D used to treat hypoparathyroidism. 2. Anorexia is a common unwanted effect due to increased calcium absorption causing decreased appetite. 3. Tetany is incorrect as vitamin D helps maintain calcium levels to prevent tetany. 4. CNS toxicity is incorrect as dihydrotachysterol does not typically affect the central nervous system. 5. Lymphocytopenia is incorrect as it is not a known side effect of dihydrotachysterol. Summary: The correct answer is B because anorexia is a common unwanted effect of dihydrotachysterol due to increased calcium absorption, while the other choices are incorrect as they do not align with the mechanism of action or known side effects of this medication.

Correct Answer: D

Rationale: Rationale for Correct Answer D: Aldosterone is a hormone that regulates salt and water balance by affecting sodium and potassium levels. Hydrochlorothiazide inhibits sodium reabsorption, while amiloride blocks potassium excretion. Since aldosterone promotes sodium reabsorption and potassium excretion, the presence of aldosterone would counteract the effects of both drugs. Therefore, the correct answer is D, as neither drug requires aldosterone for effectiveness. Choice A (Hydrochlorothiazide) is incorrect because it works independently of aldosterone by inhibiting sodium reabsorption in the kidneys. Choice B (Amiloride) is also incorrect as it directly blocks sodium channels in the kidneys, regardless of aldosterone levels. Choice C is incorrect because both drugs are effective regardless of aldosterone presence.

Correct Answer: B

Rationale: The correct answer is B: Rifampin. Rifampin inhibits bacterial RNA synthesis by binding to the bacterial RNA polymerase enzyme. This prevents transcription of bacterial RNA, leading to inhibition of bacterial growth. Erythromycin (A) inhibits protein synthesis, Chloramphenicol (C) inhibits the peptidyl transferase activity during protein synthesis, and Imipinem (D) is a β-lactam antibiotic that inhibits bacterial cell wall synthesis. Thus, only Rifampin specifically targets bacterial RNA synthesis among the given choices.

Correct Answer: B

Rationale: The correct answer is B: Hepatotoxicity, peripheral neuropathy. Isoniazid is a commonly used medication for tuberculosis treatment. Hepatotoxicity is a well-known side effect, which can manifest as hepatitis or liver damage. Peripheral neuropathy is another common side effect, characterized by numbness, tingling, or burning sensations in the extremities. These effects are due to the drug's metabolism in the liver and its interference with nerve function. Choice A is incorrect as cardiotoxicity is not a known side effect of isoniazid. Choice C, loss of hair, is not a commonly reported side effect of isoniazid. Choice D, immunotoxicity, is not a major side effect associated with isoniazid use.