Indicate the reversible cholinesterase inhibitor

Correct Answer: A

Rationale: The correct answer is A: Physostigmine, which penetrates the blood-brain barrier. Physostigmine is a reversible cholinesterase inhibitor that can cross the blood-brain barrier, allowing it to exert its effects on cholinesterase enzymes in the central nervous system. This property makes it useful in conditions where increasing cholinergic activity in the brain is desired, such as in the treatment of Alzheimer's disease. Choice B, Edrophonium, is a reversible cholinesterase inhibitor but does not effectively penetrate the blood-brain barrier. Choice D, Neostigmine, is also a reversible cholinesterase inhibitor but is primarily used for its effects on peripheral cholinesterase enzymes and does not cross the blood-brain barrier effectively.

Correct Answer: B

Rationale: Step 1: Norepinephrine is a neurotransmitter that acts on both alpha and beta receptors. Step 2: Norepinephrine has more potent effects on alpha receptors compared to epinephrine. Step 3: Choice A is correct as norepinephrine has similar effects on beta1 receptors in the heart and similar potency at alpha receptors. Step 4: Choice C is incorrect as tissue necrosis is associated with dopamine, not norepinephrine. Step 5: Choice D is incorrect as norepinephrine increases both diastolic and systolic blood pressure. Step 6: Choice B is correct as norepinephrine does not decrease mean pressure below normal before returning to the control value, making it the exception among the effects listed.

Correct Answer: B

Rationale: The correct answer is B: Phentolamine. Phentolamine is an alpha receptor antagonist that can rapidly reverse the vasoconstriction caused by local infiltration of norepinephrine. It works by blocking alpha receptors, leading to vasodilation and improved blood flow in the affected area. Propranolol (A) is a beta-blocker and not effective in reversing alpha receptor-mediated vasoconstriction. Tamsulosin (C) is an alpha-1 blocker primarily used for benign prostatic hyperplasia, not for acute vasoconstriction reversal. Ergotamine (D) is a vasoconstrictor used in treating migraines, which would exacerbate the problem in this scenario.

Correct Answer: D

Rationale: The correct answer is D: All of the above. Barbiturates have a low therapeutic index, leading to a narrow range between therapeutic and toxic doses. They suppress REM sleep, which can lead to negative effects on sleep quality. Barbiturates also have a high potential for physical dependence and abuse, making them less desirable compared to benzodiazepines. Therefore, all the given reasons collectively contribute to the shift towards using hypnotic benzodiazepines over barbiturates.

Correct Answer: D

Rationale: The correct answer is D: All of the above. Valproate's mechanism of action involves multiple pathways. 1. Valproate facilitates GABA synthesis by inhibiting GABA breakdown enzyme and enhancing GABA accumulation. 2. It inhibits voltage-sensitive Na+ channels, reducing neuronal excitability. 3. It also inhibits low threshold (T-type) Ca2+ channels, further reducing neuronal excitability. These combined actions lead to increased GABAergic transmission and decreased excitatory neurotransmission, contributing to its antiepileptic and mood stabilizing effects. Other choices are incorrect because they do not encompass all the mechanisms involved in valproate's action.