Which of the following hypnotic drugs is used intravenously as anesthesia?

Correct Answer: A

Rationale: The correct answer is A: Thiopental. Thiopental is used intravenously as anesthesia due to its rapid onset and short duration of action, making it suitable for induction of anesthesia. Phenobarbital, Flurazepam, and Zolpidem are not typically used for anesthesia due to slower onset, longer duration, and different mechanisms of action. Thiopental's pharmacokinetic profile and effectiveness in inducing anesthesia make it the most appropriate choice among the options provided.

Correct Answer: D

Rationale: The correct answer is D: All of the above. Opioid analgesics with affinity for the mu receptor exert their principal central nervous system effects through various mechanisms. 1. Analgesia: Opioids bind to mu receptors, inhibiting pain transmission in the CNS. 2. Respiratory depression: Stimulation of mu receptors in the brainstem suppresses the respiratory drive. 3. Euphoria: Activation of mu receptors in the limbic system can induce feelings of euphoria. Therefore, all these effects are collectively produced by opioids with mu receptor affinity. Other choices are incorrect because they do not encompass the comprehensive range of central nervous system effects associated with this class of analgesics.

Correct Answer: C

Rationale: The correct answer is C: Thromboembolism. Aspirin is commonly used prophylactically to prevent blood clots and reduce the risk of thromboembolic events, such as heart attacks and strokes. It inhibits platelet aggregation, making it effective in preventing clot formation. Noncardiogenic pulmonary edema (A), peptic ulcers (B), and metabolic acidosis (D) are not conditions for which aspirin is typically used prophylactically. Pulmonary edema is treated with diuretics, peptic ulcers with proton pump inhibitors, and metabolic acidosis with appropriate fluid and electrolyte management.

Correct Answer: D

Rationale: The correct answer is D: Fluoxetine. Fluoxetine is a selective serotonin reuptake inhibitor (SSRI) because it specifically targets the reuptake of serotonin in the brain, leading to increased levels of serotonin available for neurotransmission. Phenelzine (A) is a monoamine oxidase inhibitor, Desipramine (B) is a tricyclic antidepressant, and Maprotiline (C) is a tetracyclic antidepressant. These medications work through different mechanisms than SSRIs and do not specifically target serotonin reuptake. Therefore, they are not classified as SSRIs.

Correct Answer: B

Rationale: The correct answer is B: Caffeine. Caffeine acts centrally mainly by blocking adenosine receptors. Adenosine normally inhibits the release of neurotransmitters, but when adenosine receptors are blocked by caffeine, this inhibition is reduced, leading to increased alertness and wakefulness. Meridil (A), Amphetamine (C), and Sydnophen (D) do not primarily act by blocking adenosine receptors. Meridil is a sympathomimetic amine, Amphetamine is a psychostimulant that primarily acts by increasing the release of dopamine and norepinephrine, and Sydnophen is a stimulant drug.