Tick out the drug belonging to non-narcotic antitussives:

Correct Answer: A

Rationale: The correct answer is A: Libexine. Non-narcotic antitussives, such as Libexine, do not contain opioids or narcotics, making them safer for use without the risk of dependence or addiction. Libexine works by suppressing the cough reflex in the brainstem without causing sedation or respiratory depression. Choice B, Tusuprex, is incorrect as it contains codeine, which is a narcotic antitussive. Choice C, Codeine, is also incorrect as it is a narcotic antitussive that acts on the central nervous system to suppress cough reflex. Choice D, Aethylmorphine hydrochloride, is incorrect as it is a semi-synthetic opioid derivative, making it a narcotic antitussive.

Correct Answer: B

Rationale: The correct answer is B: Digitoxin is greater than digoxin. This is because digitoxin has a longer half-life compared to digoxin. Digitoxin is a more potent cardiac glycoside with a slower elimination rate, leading to a longer duration of action in the body. Digoxin, on the other hand, has a shorter half-life and is eliminated more rapidly. Therefore, digitoxin remains in the body for a longer duration, making it have a greater half-life compared to digoxin. Choices A, C, and D are incorrect as they do not relate to the comparison of half-lives between digoxin and digitoxin.

Correct Answer: D

Rationale: The correct answer is D because increased myocardial oxygen consumption is not a mechanism of nitrate's beneficial clinical effect. Nitrate works by decreasing myocardial oxygen requirement, relieving coronary artery spasm, and improving perfusion to ischemic myocardium, which collectively help in managing angina. Increased myocardial oxygen consumption would worsen ischemia, contradicting the purpose of using nitrates.

Correct Answer: C

Rationale: Step 1: Vasoconstrictors cause constriction of blood vessels. Step 2: Constriction of blood vessels leads to decreased peripheral blood flow. Step 3: Decreased peripheral blood flow can result in reduced oxygen delivery to tissues. Step 4: General unwanted effects of vasoconstrictors include decreased peripheral blood flow, making choice C correct. Summary: A: Incorrect - Vasoconstrictors do not always directly increase arterial pressure. B: Incorrect - Vasoconstrictors may not always increase cardiac output. D: Incorrect - Vasoconstrictors do not directly increase blood volume; they may redistribute blood flow.

Correct Answer: C

Rationale: The correct answer is C because thyrotrophin, also known as thyroid-stimulating hormone (TSH), stimulates the release of thyroxine (T4) and triiodothyronine (T3) from the thyroid gland. This occurs through the activation of adenylate cyclase and the subsequent increase in cAMP levels, leading to the synthesis and secretion of thyroid hormones. Choices A and B are incorrect as they pertain to the iodine-related processes within the thyroid follicles, but TSH itself does not directly stimulate these processes. Choice D is also incorrect as TSH does not promote the de-iodination of thyroid hormones; instead, it supports their synthesis and release.