Which of the following local anesthetics is a short-acting drug?

Correct Answer: A

Rationale: The correct answer is A: Procaine. It is a short-acting drug due to its rapid metabolism by plasma esterases, resulting in a shorter duration of action compared to the other choices. Procaine's quick onset and short duration make it suitable for minor procedures. Tetracaine, Bupivacaine, and Ropivacaine are all long-acting local anesthetics with slower metabolism and longer durations of action, making them more suitable for prolonged surgeries or chronic pain management.

Correct Answer: D

Rationale: The correct answer is D (Both B and C). Succinylcholine and mivacurium are metabolized by plasma cholinesterase. An abnormal variant of plasma cholinesterase (B) can lead to prolonged neuromuscular blockade. Additionally, hepatic disease (C) can impair the metabolism of these drugs, further prolonging their effects. Therefore, in patients with both abnormal plasma cholinesterase and hepatic disease, the neuromuscular blockade can be significantly prolonged. Renal failure (A) does not directly impact the metabolism of succinylcholine and mivacurium, so it is not a significant factor in this context.

Correct Answer: A

Rationale: The correct answer is A: Xylometazoline. Xylometazoline is an alpha2-selective agonist, which means it specifically targets alpha2-adrenergic receptors. By activating these receptors, xylometazoline promotes constriction of the nasal mucosa, leading to reduced swelling and congestion. Phenylephrine (B) and methoxamine (C) are alpha1-selective agonists, not alpha2-selective, so they would not promote constriction of nasal mucosa. Epinephrine (D) is a non-selective agonist that acts on both alpha and beta receptors, leading to a broader range of effects, not specifically nasal constriction.

Correct Answer: A

Rationale: The correct answer is A because beta-blocking agents do not affect plasma lipid levels directly. Beta-blockers can decrease HDL levels and increase VLDL levels, which is opposite to choice A. Bronchoconstriction (B) is a common side effect of non-selective beta-blockers due to their action on beta-2 receptors in the lungs. Decrease in aqueous humor production (C) is a therapeutic effect of beta-blockers in treating glaucoma. "Membrane-stabilizing" action (D) refers to the ability of some beta-blockers to block sodium channels in the cardiac muscle, leading to antiarrhythmic effects.

Correct Answer: C

Rationale: During slow wave sleep (stage 3 and 4 NREM sleep), somnambulism (sleepwalking) and nightmares occur. This is because these stages are characterized by deep sleep, where the brain activity is at its lowest, making it more likely for these types of sleep disturbances to happen. Choice A is incorrect because dreams primarily occur during REM sleep, not slow wave sleep. Choice B is incorrect as the secretion of adrenal steroids typically peaks in the early morning, not during slow wave sleep. Choice D is incorrect as the secretion of somatotropin (growth hormone) is actually at its highest during slow wave sleep, aiding in physical growth and repair.