Barbiturate abstinent syndrome is shown by:

Correct Answer: D

Rationale: The correct answer is D because barbiturate abstinent syndrome can manifest as a variety of symptoms including crisis by 3 days of abstention, anxiety, mydriasis, myasthenia, muscular convulsions, vomiting, diarrhea, and psychosis as delirium with color visual and auditory hallucinations. Each of the other choices (A, B, C) only represents a subset of the symptoms associated with barbiturate abstinent syndrome, while choice D encompasses all possible manifestations, making it the correct and comprehensive answer.

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.

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.