The following statements concerning mechanism of calcium channel blockers’ action are true, EXCEPT:

Correct Answer: A

Rationale: Rationale: A: Incorrect. Calcium channel blockers do not release nitric oxide. They mainly block calcium entry into cells. B: Correct. L-type calcium channels are the main target of calcium channel blockers. C: Correct. Calcium channel blockers decrease oxygen demand and increase oxygen delivery in angina. D: Correct. Calcium channel blockers reduce calcium entry, leading to relaxation in smooth muscle and decreased contractility in cardiac muscle. Therefore, choice A is incorrect because calcium channel blockers do not release nitric oxide.

Correct Answer: D

Rationale: The correct answer is D: For treatment of simple obesity. Thyroid hormones are not indicated for the treatment of simple obesity as they do not directly affect weight loss. A: Cretinism - Thyroid hormones are indicated for the treatment of cretinism, a condition caused by thyroid hormone deficiency in infancy. B: Myxoedema - Thyroid hormones are indicated for the treatment of myxoedema, a severe form of hypothyroidism in adults. C: Hashimoto's disease - Thyroid hormones are indicated for the treatment of Hashimoto's disease, an autoimmune condition that leads to hypothyroidism. In summary, thyroid hormones are indicated for conditions related to thyroid hormone deficiencies and dysfunctions, but not for the treatment of simple obesity.

Correct Answer: A

Rationale: The correct answer is A: Antiprogestin. Mifepristone is a synthetic steroid that acts as an antiprogestin by competitively binding to progesterone receptors, blocking the effects of progesterone. It is commonly used for medical abortion and in the treatment of conditions like Cushing's syndrome. Explanation for incorrect choices: B: Antiandrogen - Mifepristone does have some antiandrogenic properties, but its primary mechanism of action is as an antiprogestin. C: Antiestrogen - Mifepristone is not an antiestrogen; it does not block estrogen receptors. D: Androgen - Mifepristone is not an androgen; it is a synthetic steroid with antiprogestational activity.

Correct Answer: A

Rationale: The correct answer is A. Allergic reaction is a response of the immune system to an allergen that the body has previously been sensitized to. This response can be local or generalized, involving various symptoms such as itching, hives, swelling, and in severe cases, anaphylaxis. Choice B describes inflammation, not specifically related to allergies. Choices C and D are unrelated medications. In summary, choice A is correct because it accurately defines an allergic reaction, while the other choices do not specifically address the nature of allergies.

Correct Answer: A

Rationale: The correct answer is A because vitamin-like compounds are a group of compounds that are essential for health but are not classified as vitamins. These compounds have specific roles in the body, particularly during periods of rapid growth and development. They are not inorganic nutrients (B) or organic substances needed in large quantities (C). They are also not products of endocrine gland secretion (D). The key is to understand that vitamin-like compounds are essential for certain stages of development and growth, making choice A the most appropriate answer.