Cordiamine is useful in the treatment of:

Correct Answer: D

Rationale: The correct answer is D because Cordiamine, also known as Nikethamide, is a respiratory and circulatory stimulant. It is used to treat hypotension by increasing blood pressure, coronary insufficiency by improving blood flow to the heart, and respiratory insufficiency by stimulating breathing. Therefore, it is effective in treating all the conditions mentioned in choices A, B, and C. Choices A, B, and C are incorrect because Cordiamine does not specifically target only one of these conditions; rather, it addresses all of them due to its dual stimulant action on both the circulatory and respiratory systems.

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: A

Rationale: The correct answer is A: Phenolphthalein. Phenolphthalein is a stimulant laxative that irritates the gut lining, leading to increased peristalsis and bowel movements. This mechanism helps relieve constipation. Methyl cellulose (B) is a bulk-forming laxative that works by absorbing water to form a soft bulk, not by irritating the gut. Proserine (C) is a cholinesterase inhibitor used for myasthenia gravis, not for gut stimulation. Mineral oil (D) is a lubricant laxative that works by coating the stool and preventing water absorption, not by irritating the gut.

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.