Which of the following statements concerning potassium channel openers is true?

Correct Answer: D

Rationale: Correct Answer: D Rationale: 1. Potassium channel openers increase the permeability of potassium channels, specifically ATP-dependent K channels. 2. This increased permeability results in stabilizing the membrane potential of excitable cells near the resting potential. 3. By stabilizing the membrane potential, these agents help regulate cell excitability and function. 4. This mechanism of action is crucial in conditions like cardiac arrhythmias and smooth muscle hyperactivity. Summary of Incorrect Choices: A. This statement incorrectly associates potassium channel openers with decreasing calcium current, which is not their primary mechanism of action. B. This statement inaccurately attributes reflex and vascular dilative actions to potassium channel openers, which are not their primary effects. C. This statement wrongly suggests that the beneficial effects of potassium channel openers are primarily hemodynamic, while their main mechanism is through potassium channel permeability modulation.

Correct Answer: A

Rationale: The correct answer is A: Oral route. Insulin cannot be administered orally because it gets degraded by stomach enzymes. The correct routes for insulin administration are B: Intravenous route, C: Subcutaneous route, and D: Intramuscular route. These routes allow for direct absorption into the bloodstream without degradation. Intravenous route ensures rapid onset, subcutaneous route is commonly used for self-administration, and intramuscular route provides slower absorption.

Correct Answer: B

Rationale: The correct answer is B: Triamcinolone. Triamcinolone is an intermediate-acting glucocorticoid due to its duration of action, which typically lasts between 12 to 36 hours. Cortisone (A) is a short-acting glucocorticoid, with a duration of action of about 8-12 hours. Betamethasone (C) is a long-acting glucocorticoid, with a duration of action of around 36-54 hours. Choice D is incorrect as not all of the listed glucocorticoids are intermediate-acting.

Correct Answer: D

Rationale: The correct answer is D, Suprastine, because it is not a second-generation antihistamine. Second-generation antihistamines are known for having minimal sedative effects and longer duration of action compared to first-generation antihistamines. Astemizole, Loratadine, and Cetirizine are all second-generation antihistamines with these characteristics. Suprastine, on the other hand, is a first-generation antihistamine and does not meet the criteria for being a second-generation antihistamine. Therefore, it is the exception in this list.

Correct Answer: D

Rationale: The correct answer is D, "All of the above." Vitamin A deficiency can lead to various symptoms, including night blindness (choice A), xerophthalmia and keratomalacia (choice B), and various epithelial tissue defects that can result in decreased resistance to infective diseases, male and female infertility (choice C). These symptoms occur due to the role of vitamin A in maintaining healthy vision, skin, and mucous membranes. Therefore, choosing option D is correct as it encompasses all the possible deficiency symptoms associated with vitamin A deficiency.