A M-cholinimimetic agent is:

Correct Answer: B

Rationale: The correct answer is B: Pilocarpine. Pilocarpine is a M-cholinomimetic agent because it selectively activates muscarinic receptors. It is commonly used to treat conditions like glaucoma by causing pupillary constriction and lowering intraocular pressure. Carbachol (A) and Bethanechol (D) are non-selective cholinomimetics, affecting both muscarinic and nicotinic receptors. Acetylcholine (C) is not a practical drug due to its rapid degradation by acetylcholinesterase.

Correct Answer: C

Rationale: The correct answer is C: Stimulation of insulin secretion. Alpha-receptor stimulation leads to vasoconstriction, contraction of smooth muscles in the bladder base, uterus, and prostate, as well as platelet aggregation. Insulin secretion is primarily regulated by beta cells in the pancreas, which are influenced by glucose levels, not alpha-receptor stimulation. Therefore, the effects listed in options A, B, and D are all consistent with alpha-receptor stimulation, while option C is not.

Correct Answer: C

Rationale: The correct answer is C: Bronchospasm. Alpha-receptor antagonists typically do not cause bronchospasm as they primarily act on alpha-adrenergic receptors involved in vasoconstriction. A is correct as alpha-blockers reduce peripheral resistance and blood pressure. B is correct as they can reverse the pressor response of epinephrine. D is correct as they can lead to postural hypotension and reflex tachycardia due to vasodilation. In summary, bronchospasm is not a characteristic of alpha-receptor antagonists, making choice C the correct answer.

Correct Answer: B

Rationale: The correct answer is B: FALSE. Hypnotic benzodiazepines are not enzyme inducers, unlike barbiturates. Benzodiazepines act on GABA receptors, enhancing inhibitory neurotransmission, while barbiturates directly activate GABA receptors. Therefore, benzodiazepines do not induce enzymes involved in drug metabolism, making them less potent enzyme inducers compared to barbiturates. Choices A, C, and D are incorrect because hypnotic benzodiazepines do not induce enzymes like barbiturates do.

Correct Answer: A

Rationale: The correct answer is A: Phenobarbital sodium. It is the drug of choice for status epilepticus in infants and children due to its rapid onset of action, effectiveness in controlling seizures, and safety profile. Phenobarbital is a barbiturate that acts as a GABA agonist, enhancing inhibitory neurotransmission. Clonazepam (B) is also effective but may not provide as rapid seizure control. Ethosuximide (C) is indicated for absence seizures, not status epilepticus. Phenytoin (D) is not recommended in infants due to the risk of causing severe adverse effects like cardiac arrhythmias and hypotension.