A 54-year-old woman suffering from initial insomnia was prescribed a hypnotic drug that increases the activity of a major neurotransmitter system in the brain. Which neurotransmitter system was most likely involved in the therapeutic action of that drug?

Correct Answer: D

Rationale: The correct answer is D: GABAergic. GABA is the major inhibitory neurotransmitter in the brain, and drugs that enhance GABA activity, such as benzodiazepines, are commonly used as hypnotics to treat insomnia. By increasing GABAergic activity, the drug helps to promote relaxation and induce sleep. Choices A, B, and C are incorrect because they do not directly relate to the therapeutic action of hypnotic drugs for insomnia. Cholinergic, noradrenergic, and glutamatergic systems are not primarily involved in promoting sleep and reducing insomnia symptoms.

Correct Answer: C

Rationale: The correct answer is C: Anterograde amnesia. Upon recovery from sedation, the patient most likely experienced anterograde amnesia, which is the inability to form new memories after sedation. This occurs due to the effects of sedative medications on the brain's ability to encode and store new information temporarily. This symptom is commonly associated with sedative medications and is a typical outcome of sedation procedures. A: Nausea and vomiting are common side effects of sedation but are more likely to occur during or shortly after sedation, rather than upon recovery. B: Increased respiratory rate may occur during sedation due to the effects of sedative medications on the respiratory system, but it is not a typical symptom upon recovery. D: Limb muscle spasms are not typically associated with recovery from sedation and are more likely to be a sign of a different medical condition or side effect of a different medication.

Correct Answer: D

Rationale: The correct answer is D: Drug S. Potency refers to the amount of drug needed to produce a specific effect. Drug S has the highest potency among the options because it requires the smallest dose to achieve the desired effect compared to Drugs P, Q, and R. In laboratory testing, Drug S consistently showed a strong and rapid onset of action at lower doses, making it the most potent inhalational anesthetic among the options. Drug S is therefore the correct choice for having the highest potency. Choices A, B, and C are incorrect because they do not exhibit the same level of potency as Drug S based on the laboratory testing results.

Correct Answer: D

Rationale: The correct answer is D: The addition of nitrous oxide. Nitrous oxide is known to decrease minimum alveolar concentration (MAC) of anesthetic agents, leading to a lower concentration needed to maintain anesthesia. This is due to its anesthetic properties and synergistic effects with other anesthetics. Choice A (cancer) and C (age) are unlikely to directly affect MAC levels. Choice B (use of two anesthetics) might actually increase MAC rather than decrease it, making it an incorrect choice.

Correct Answer: D

Rationale: The correct answer is D: Convulsions. Lidocaine is a local anesthetic that can cause central nervous system toxicity, leading to symptoms like seizures or convulsions. When administered near the brachial plexus for a peripheral nerve block, lidocaine can inadvertently reach systemic circulation, increasing the risk of CNS side effects. Ventricular tachycardia (A) is a cardiac adverse effect, not commonly associated with lidocaine toxicity. Abdominal colic (B) is unrelated to lidocaine administration near the brachial plexus. Drowsiness (C) is a common systemic side effect of lidocaine but is less likely to occur after administration near the brachial plexus compared to CNS effects like convulsions.