Dependence is often associated with tolerance to a drug, a physical abstinence syndrome, and psychological dependence (craving). This consideration is:

Correct Answer: A

Rationale: The correct answer is A: TRUE. Dependence is indeed associated with tolerance to a drug, physical withdrawal symptoms upon discontinuation, and psychological craving. Tolerance indicates a reduced response to a drug over time, withdrawal symptoms occur when the drug is stopped abruptly, and psychological dependence leads to a strong desire to continue using the drug despite negative consequences. Choices B, C, and D are incorrect because they do not accurately reflect the comprehensive nature of drug dependence and its associated factors.

Correct Answer: B

Rationale: The correct answer is B: Scopolamine. Scopolamine is rapidly and fully distributed into the central nervous system (CNS) due to its high lipid solubility. It has a greater effect than most other antimuscarinic agents because of its ability to cross the blood-brain barrier efficiently. Atropine (A) has less CNS penetration than scopolamine. Homatropine (C) has a shorter duration of action and lower CNS penetration. Ipratropium (D) is primarily used for its bronchodilator effects and has minimal CNS penetration. Therefore, based on its pharmacokinetic properties, scopolamine is the most suitable option for rapid and potent CNS effects among the choices provided.

Correct Answer: A

Rationale: The correct answer is A: Pipecuronium. Pipecuronium is primarily eliminated through renal excretion, so it can accumulate in patients with renal failure leading to prolonged effects and potential toxicity. Succinylcholine (B) is metabolized by plasma cholinesterase and not affected by renal function. Atracurium (C) and Rapacuronium (D) are also not primarily renally eliminated, making them safer options in patients with renal failure.

Correct Answer: D

Rationale: Step-by-step rationale: 1. Phenylephrine is a sympathomimetic drug that acts as a selective alpha-1 adrenergic agonist. 2. In a hypotensive emergency, vasoconstriction is needed to increase blood pressure. 3. Phenylephrine causes vasoconstriction by stimulating alpha-1 receptors, raising blood pressure. 4. Xylometazoline (A) is a nasal decongestant, Ephedrine (B) acts on multiple receptors, and Terbutaline (C) is a beta-2 agonist, not ideal for hypotensive emergencies.

Correct Answer: B

Rationale: The correct answer is B: Oxprenolol. Oxprenolol is a beta receptor antagonist with intrinsic sympathomimetic activity, meaning it has partial agonist activity along with blocking effects. This can result in less reduction of heart rate and blood pressure compared to non-selective beta blockers like Propranolol (A). Metoprolol (C) and Carvedilol (D) are both beta blockers without intrinsic sympathomimetic activity, making them incorrect choices.