Which of the following local anesthetics is an acetanilide derivative?

Correct Answer: B

Rationale: The correct answer is B: Lidocaine. Lidocaine is an acetanilide derivative because it contains an acetanilide group in its chemical structure, making it a member of this specific chemical class of local anesthetics. Tetracaine is an ester derivative, not an acetanilide derivative. Cocaine is a tropane alkaloid derivative. Procaine is an ester derivative, not an acetanilide derivative. Therefore, based on the chemical structure and classification of local anesthetics, lidocaine is the only correct option.

Correct Answer: A

Rationale: The correct answer is A: Neostigmine. Neostigmine is a cholinesterase inhibitor that increases the levels of acetylcholine, helping counteract antimuscarinic effects. By inhibiting the breakdown of acetylcholine, neostigmine enhances cholinergic transmission, thereby reversing the antimuscarinic effects. Summary: - B: Hexametonium is a ganglionic blocker used to reduce sympathetic activity, not to treat antimuscarinic effects. - C: Homatropine is an anticholinergic drug that would exacerbate antimuscarinic effects, not treat them. - D: Acetylcholine itself would not be effective in treating antimuscarinic effects as it would be rapidly degraded by acetylcholinesterase.

Correct Answer: B

Rationale: Beta1 receptor stimulation primarily affects the heart. Stimulation leads to increased contractility, tachycardia, and increased conduction velocity in the atrioventricular node. However, bronchodilation is not a direct effect of beta1 receptor stimulation. Beta2 receptors are responsible for bronchodilation, not beta1 receptors. Therefore, choice B is incorrect. Choices A, C, and D are all correct effects of beta1 receptor stimulation.

Correct Answer: D

Rationale: The correct answer is D: Phentolamine. Phentolamine is an imidazoline derivative and a potent competitive antagonist at both alpha1 and alpha2 receptors. It blocks the effects of norepinephrine at these receptors. Prazosin (A) is an alpha1 antagonist, Labetalol (B) is a non-selective alpha and beta blocker, and Phenoxybenzamine (C) is a non-selective irreversible alpha blocker. Therefore, Phentolamine is the only drug that fits the description provided in the question.

Correct Answer: D

Rationale: The correct answer is D because all three drugs listed (Flurazepam, Zaleplon, Triazolam) do not significantly alter hepatic drug-metabolizing enzyme activity. These drugs primarily act on GABA receptors in the central nervous system, rather than affecting hepatic enzymes. Therefore, they do not interfere with the metabolism of other drugs in the liver. Choices A, B, and C are incorrect because all of them are hypnotic drugs that do not alter hepatic drug-metabolizing enzyme activity.