Which of the following local anesthetics is used for infiltrative and regional anesthesia?

Correct Answer: D

Rationale: The correct answer is D: All of the above. Dibucaine, Lidocaine, and Mepivacaine are all local anesthetics commonly used for infiltrative and regional anesthesia. These agents work by blocking sodium channels, preventing the generation and propagation of action potentials in nerves. They are effective for producing anesthesia in a localized area, making them suitable for procedures like dental work, minor surgeries, and nerve blocks. Each of these local anesthetics has a slightly different onset, duration, and potency, allowing for flexibility in choosing the most appropriate agent based on the specific clinical situation. Therefore, choosing all of the above options is correct as they are all suitable choices for infiltrative and regional anesthesia.

Correct Answer: D

Rationale: The correct answer is D: Succinylcholine. Succinylcholine can cause cardiac arrhythmias by inducing hyperkalemia, especially in patients with certain conditions like burns, denervation injuries, or spinal cord injuries. This hyperkalemia can lead to dangerous arrhythmias such as ventricular tachycardia or fibrillation. Vecuronium (A), Tubocurarine (B), and Rapacuronium (C) are not known to cause cardiac arrhythmias as they do not have the same mechanism of action as Succinylcholine.

Correct Answer: B

Rationale: The correct answer is B: Bronchodilation. Ephedrine is a sympathomimetic amine that acts on alpha and beta adrenergic receptors. It primarily stimulates beta-2 adrenergic receptors in the lungs, leading to bronchodilation. This action helps in the treatment of asthma and other respiratory conditions. Miosis (choice A) is constriction of the pupil, which is not a known effect of ephedrine. Hypotension (choice C) is low blood pressure, but ephedrine is more likely to cause hypertension due to its vasoconstrictive effects. Bradycardia (choice D) is a slow heart rate, but ephedrine usually causes tachycardia due to its stimulatory effects on the heart.

Correct Answer: C

Rationale: The correct answer is C: Nadolol. Nadolol is a non-selective beta blocker with a long half-life, leading to an extended duration of action. It is typically dosed once daily, making it convenient for patients. Metoprolol (A) and Propranolol (B) have shorter durations of action compared to Nadolol. Pindolol (D) is a partial beta agonist and does not exhibit a long duration of action like Nadolol.

Correct Answer: B

Rationale: The correct answer is B: Zolpidem. Zolpidem is a hypnotic drug that selectively binds to the BZ1 receptor subtype, which enhances the inhibitory function of the neurotransmitter GABA. This specific binding to the BZ1 receptor subtype results in sedative and hypnotic effects without significant anxiolytic or muscle relaxant properties. Incorrect Choices: A: Thiopental - Thiopental is a barbiturate that acts on GABA receptors but does not selectively bind to the BZ1 receptor subtype. C: Flurazepam - Flurazepam is a benzodiazepine that primarily acts on the BZ2 receptor subtype, not the BZ1 receptor subtype. D: Phenobarbital - Phenobarbital is a barbiturate that enhances GABAergic transmission but does not selectively bind to the BZ1 receptor subtype. In summary, Zolpidem is the correct answer because it specifically targets the