Hydralazine (a vasodilator) can produce:

Correct Answer: B

Rationale: Rationale: Hydralazine is known to cause tachycardia as a side effect due to its vasodilatory properties. Lupus erythematosus can also be induced by hydralazine through its autoimmune effects. Seizures, extrapyramidal disturbances, acute hepatitis, and aplastic anemia are not typically associated with hydralazine use. Thus, option B is the correct choice.

Correct Answer: D

Rationale: Rationale: The major synthetic estrogens are Dienestrol, Diethylstilbestrol, and Benzestrol, but not Estradiol. Estradiol is a natural estrogen produced by the ovaries. Therefore, D is the correct answer. Dienestrol, Diethylstilbestrol, and Benzestrol are synthetic estrogens used in hormone replacement therapy.

Correct Answer: A

Rationale: The correct answer is A. Metamizole use is associated with serious side effects such as agranulocytosis and aplastic anemia. Agranulocytosis is a severe decrease in white blood cells, leading to increased risk of infections. Aplastic anemia is a condition where the bone marrow does not produce enough blood cells. Choices B and C are incorrect as they are not known side effects of metamizole. Salicylism is associated with aspirin toxicity, while iatrogenic Cushing's syndrome is typically caused by prolonged use of glucocorticoids, not metamizole. Therefore, the correct choice is A as it accurately reflects the serious side effects of metamizole.

Correct Answer: A

Rationale: The correct answer is A: 18-24 hours. The half-life of a drug is the time it takes for half of the drug to be removed from the body. OKT-3 has a relatively short half-life, typically ranging from 18 to 24 hours. This means that after 18-24 hours, only half of the initial dose of OKT-3 will remain in the body. Choice B (25-35 minutes) is too short for a drug like OKT-3 which is used for immunosuppression and requires a longer duration of action. Choice C (4-16 hours) falls within the correct range but is not as specific as the 18-24 hours range. Choice D (21 days) is too long for OKT-3, as drugs with such long half-lives are typically not used for immunosuppression due to the difficulty in adjusting dosages.

Correct Answer: D

Rationale: The correct answer is D: All of the above. Isoniazide, ethanol, and carbamazepine are all antivitamins that interfere with the metabolism of vitamin B6. Isoniazide inhibits the conversion of vitamin B6 to its active form, ethanol decreases the absorption and utilization of vitamin B6, and carbamazepine reduces the plasma levels of vitamin B6. Therefore, all three choices prevent vitamin B6 from exerting its metabolic effects. The other choices are incorrect because each of them individually interferes with the action of vitamin B6.