Which of the following neuromuscular blockers causes transient muscle fasciculations?

Correct Answer: C

Rationale: Step-by-step rationale: 1. Succinylcholine causes transient muscle fasciculations due to its depolarizing mechanism of action. 2. It binds to nicotinic acetylcholine receptors, causing initial muscle twitching. 3. This fasciculation phase is a distinct feature of succinylcholine. 4. Mivacurium, Pancuronium, and Tubocurarine are non-depolarizing blockers, so they do not cause initial muscle fasciculations. Summary: A, B, and D are incorrect because they are non-depolarizing blockers and do not induce muscle fasciculations like succinylcholine.

Correct Answer: B

Rationale: The correct answer is B because propranolol does not reduce blood flow to the brain. Propranolol is a non-selective beta-blocker that decreases cardiac work and oxygen demand (choice A), inhibits renin secretion (choice C), and increases the atrioventricular nodal refractory period (choice D). By blocking beta receptors in the heart and blood vessels, propranolol reduces heart rate, contractility, and blood pressure, leading to decreased oxygen demand. Inhibiting renin secretion helps lower blood pressure. Increasing the atrioventricular nodal refractory period can slow down the conduction of electrical impulses in the heart, helping to control heart rhythm. Therefore, choices A, C, and D are all accurate effects of propranolol on the cardiovascular system.

Correct Answer: C

Rationale: The correct answer is C: Flurazepam. Flurazepam is a benzodiazepine hypnotic drug that causes the least suppression of REM sleep compared to the other options. Benzodiazepines like flurazepam enhance the quality of sleep without significantly disrupting REM sleep. Flumazenil (A) is a benzodiazepine receptor antagonist, not a hypnotic drug. Phenobarbital (B) and Secobarbital (D) are barbiturates that are known to suppress REM sleep significantly, unlike flurazepam. In summary, flurazepam is the best choice for a hypnotic drug that minimally affects REM sleep compared to the other options provided.

Correct Answer: D

Rationale: The correct answer is D, All of the above. Phenytoin, Valproate, and Topiramate are known to have teratogenic effects. Phenytoin can cause fetal hydantoin syndrome, Valproate is associated with neural tube defects, and Topiramate can lead to cleft lip and palate. These antiseizure drugs should be used cautiously in pregnant women due to the potential harm to the developing fetus. The other choices are incorrect because only Phenytoin, Valproate, and Topiramate are specifically linked to teratogenicity.

Correct Answer: C

Rationale: Rationale: 1. Kappa and delta agonists inhibit postsynaptic neurons by opening K+ channels. 2. They also close voltage-gated Ca2+ channels on presynaptic nerve terminals. 3. Therefore, choice C (Both a and b) is correct, as it encompasses both actions. Summary: - Choice A is incorrect because it only mentions the action of opening K+ channels. - Choice B is incorrect as it only refers to closing voltage-gated Ca2+ channels. - Choice D is unrelated to the actions of kappa and delta agonists on neuronal transmission.