CNS stimulant agents belong to

Correct Answer: D

Rationale: CNS stimulant agents belong to multiple categories, including respiratory stimulants that increase breathing, psychomotor stimulants that enhance physical activity, and psychomimetic agents that induce hallucinations or altered perceptions. Therefore, the correct answer is D, "All of the above," as CNS stimulants can have effects on various functions in the central nervous system. Choices A, B, and C are incorrect because CNS stimulants do not exclusively belong to any single category, but rather have a broad range of effects on different aspects of brain function.

Correct Answer: D

Rationale: Step-by-step rationale: 1. Ondansetron is commonly used as an antiemetic, specifically for preventing nausea and vomiting caused by cancer chemotherapy. 2. It works by blocking serotonin receptors in the brain, which helps to alleviate nausea and vomiting. 3. This mechanism of action is specific to antiemetics and not antihistamines, drugs for peptic ulcers, or antiarrhythmics. 4. Therefore, the correct answer is D - Antiemetic for cancer chemotherapy. Summary: - Choice A is incorrect because ondansetron is not an antihistamine. - Choice B is incorrect because ondansetron is not used for treating peptic ulcers. - Choice C is incorrect because ondansetron is not an antiarrhythmic. - The correct answer, D, is supported by the drug's mechanism of action and primary usage as an antiemetic for cancer chemotherapy.

Correct Answer: C

Rationale: The correct answer is C because ketamine can be administered via both intravenous and intramuscular routes. Intravenous administration allows for rapid onset of action, making it ideal for induction of anesthesia. Intramuscular administration provides an alternative option for administration when intravenous access is not available. Options A and B are incorrect because ketamine can be administered via both routes. Option D is incorrect as ketamine can be administered through one or both of the mentioned routes.

Correct Answer: B

Rationale: Phenelzine belongs to the class of MAO inhibitors because it inhibits the enzyme monoamine oxidase, which leads to increased levels of neurotransmitters like serotonin, norepinephrine, and dopamine. This mechanism differs from the other classes listed. Tricyclic antidepressants (A) block the reuptake of neurotransmitters, SSRIs (C) selectively block serotonin reuptake, and atypical antidepressants (D) have diverse mechanisms but don't primarily inhibit MAO. This makes choice B the correct answer.

Correct Answer: C

Rationale: An inverse agonist is a compound that binds to the same receptor as an agonist but induces the opposite effect by decreasing the basal activity of the receptor. Beta-Carboline is the correct answer as it acts as an inverse agonist at GABA-A receptors, reducing the inhibitory effect of GABA. A: Buspirone is a partial agonist at serotonin receptors, not an inverse agonist. B: Flumazenil is a benzodiazepine receptor antagonist, not an inverse agonist. D: Zolpidem is a positive allosteric modulator of GABA-A receptors, not an inverse agonist. Summary: Beta-Carboline is the only choice that fits the definition of an inverse agonist by reducing receptor activity, making it the correct answer.