Which of the following local anesthetics is only used for surface or topical anesthesia?

Correct Answer: A

Rationale: The correct answer is A: Cocaine. Cocaine is only used for surface or topical anesthesia due to its potent vasoconstrictive properties and high potential for systemic toxicity. It is not suitable for deeper anesthesia due to its side effects. Tetracaine, Mepivacaine, and Lidocaine can be used for both surface and deeper anesthesia, unlike Cocaine.

Correct Answer: C

Rationale: The correct answer is C: Tubocurarine. Tubocurarine is a non-depolarizing neuromuscular blocker that can cause hypotension and bronchospasm as side effects due to its mechanism of action on nicotinic receptors. A: Vecuronium is a non-depolarizing neuromuscular blocker but is less likely to cause hypotension and bronchospasm. B: Succinylcholine is a depolarizing neuromuscular blocker and does not typically cause hypotension and bronchospasm. D: Rapacuronium is a neuromuscular blocker that was withdrawn from the market due to the risk of severe bronchospasm.

Correct Answer: C

Rationale: The correct answer is C because salmeterol does not stimulate heart rate, contractility, or cardiac output. Salmeterol is a long-acting beta2 agonist that primarily acts on the bronchial smooth muscles to provide bronchodilation in conditions like asthma and chronic obstructive pulmonary disease. Choice A is incorrect because salmeterol is indeed a potent selective beta2 agonist. Choice B is also incorrect as salmeterol does not cause uterine relaxation. Choice D is incorrect as salmeterol is commonly used in the therapy of asthma to provide long-term symptom control.

Correct Answer: A

Rationale: Step-by-step rationale for choice A being correct: 1. Metoprolol and atenolol are both selective beta1-adrenergic receptor antagonists. 2. Being beta1-selective means they primarily target beta1 receptors in the heart. 3. This results in decreased heart rate and reduced blood pressure. 4. Choice A is correct as it accurately describes the pharmacological action of metoprolol and atenolol. Summary of why other choices are incorrect: - Choice B (nonselective beta antagonists) is incorrect as metoprolol and atenolol are selective for beta1 receptors. - Choice C (intrinsic sympathomimetic activity) is incorrect as metoprolol and atenolol lack intrinsic sympathomimetic activity. - Choice D (anesthetic action) is incorrect as metoprolol and atenolol do not have anesthetic properties.

Correct Answer: A

Rationale: The correct answer is A: Triazolam. Triazolam has a short half-life, leading to quicker elimination from the body, which can cause a more pronounced "rebound" effect after discontinuation, resulting in rebound insomnia. Flurazepam and Temazepam have longer half-lives, so they are less likely to cause rebound insomnia. Choice D is incorrect as not all benzodiazepines cause rebound insomnia equally.