For digitalis-induced arrhythmias the following drug is favored:

Correct Answer: C

Rationale: The correct answer is C: Lidocaine. Lidocaine is favored for digitalis-induced arrhythmias due to its sodium channel blocking properties, which can help stabilize the heart rhythm. Verapamil (A) is a calcium channel blocker and may worsen arrhythmias. Amiodarone (B) is effective for various arrhythmias but may interact with digitalis. Propranolol (D) is a beta-blocker and may not be as effective as lidocaine for digitalis-induced arrhythmias.

Correct Answer: B

Rationale: The correct answer is B because at low doses, dopamine primarily acts on dopamine receptors, leading to vasodilation of renal and mesenteric vessels. This is known as the renal dose of dopamine. Choices A and C are incorrect because low doses of dopamine do not significantly impact alpha-adrenoreceptors for peripheral vasoconstriction or beta-1 adrenoreceptors for enhancing cardiac output. Choice D is incorrect as dopamine at low doses does not affect all the mentioned receptors simultaneously.

Correct Answer: B

Rationale: Step-by-step rationale: 1. Diatrizoate sodium is a contrast agent, not an antithyroid drug. 2. Propylthiouracil, Methimazole, and Potassium perchlorate are antithyroid drugs. 3. Propylthiouracil and Methimazole inhibit thyroid hormone synthesis. 4. Potassium perchlorate blocks iodine uptake by the thyroid gland, reducing hormone production. 5. Thus, Diatrizoate sodium is the correct answer as it is not an antithyroid drug.

Correct Answer: D

Rationale: The correct answer is D because mifepristone (RU-486) acts in multiple ways to terminate pregnancy. It inhibits ovulation by blocking progesterone receptors, suppresses midcycle gonadotropin release, inhibits progesterone action on the uterus during the luteal phase, induces prostaglandin release from the endometrium, facilitates luteolysis, induces menstruation, increases uterine motility, softens the cervix, and causes detachment of the embryo. Therefore, all the actions described in options A, B, and C are correct, making option D the correct choice. Options A, B, and C are incorrect because they each only describe a single aspect of mifepristone's mechanism of action, whereas option D encompasses all the actions of mifepristone.

Correct Answer: B

Rationale: Delayed allergy reaction (type IV allergic reaction) is characterized by a delayed onset, typically appearing hours after exposure. This differs from immediate allergic reactions (type I) that occur within minutes. Choice A refers to an immediate allergic response. Choice C describes type III allergic reactions involving antigen-antibody complexes, not type IV. Choice D is related to tissue damage caused by elevated antigen-antibody complexes, which is not specific to delayed allergy reactions. Thus, choice B is correct as it aligns with the delayed nature of type IV allergic reactions.