Which of the following agents is an alfa1-selective agonist?

Correct Answer: B

Rationale: Step 1: Methoxamine is an alpha1-selective agonist, meaning it specifically targets alpha1 receptors. Step 2: Alpha1 receptors are found in smooth muscles, and activation causes vasoconstriction. Step 3: Methoxamine's selective action on alpha1 receptors makes it suitable for conditions requiring vasoconstriction. Step 4: Norepinephrine (A) is a non-selective agonist for alpha and beta receptors, not specifically targeting alpha1 receptors. Step 5: Ritodrine (C) is a beta2-selective agonist used for tocolysis in preterm labor, not targeting alpha1 receptors. Step 6: Ephedrine (D) is a mixed-acting sympathomimetic that acts on both alpha and beta receptors, not alpha1-selective.

Correct Answer: B

Rationale: The correct answer is B because imidazopyridines are known to be selective agonists of the BZ1 (omega1) subtype of BZ receptors. This is based on their specific binding affinity and activity at the BZ1 receptor subtype, which distinguishes them from other receptor subtypes. Imidazopyridines do not act as partial agonists at brain 5-TH1A receptors (choice A), competitive antagonists of BZ receptors (choice C), or nonselective agonists of both BZ1 and BZ2 receptor subtypes (choice D). By being selective agonists of the BZ1 subtype, imidazopyridines exhibit unique pharmacological properties that make them suitable for targeting specific therapeutic outcomes related to the BZ1 receptor subtype.

Correct Answer: C

Rationale: The correct answer is C: Vigabatrin. Vigabatrin irreversibly inhibits GABA-T by irreversibly binding to its active site, leading to a sustained increase in GABA levels. This results in enhanced GABAergic neurotransmission. Diazepam (A) and Phenobarbital (B) are not inhibitors of GABA-T. Felbamate (D) acts by blocking NMDA receptors and enhancing GABAergic transmission, but it does not directly inhibit GABA-T.

Correct Answer: D

Rationale: The correct answer is D: Amantadine. Amantadine is an antiviral agent used in the prophylaxis of influenza A2 by inhibiting the viral replication process. Selegiline (A) is a monoamine oxidase inhibitor used in Parkinson's treatment. Sinemet (B) is a combination of carbidopa and levodopa for Parkinson's symptoms. Pergolide (C) is a dopamine agonist used in Parkinson's disease but has been withdrawn due to side effects. Amantadine is the only antiparkinsonian drug in the list with antiviral properties specifically used for influenza A2.

Correct Answer: B

Rationale: The correct answer is B: Disulfiram. Disulfiram inhibits the enzyme aldehyde dehydrogenase, leading to accumulation of acetaldehyde when alcohol is consumed. This causes a noxious reaction (e.g., nausea, vomiting) as acetaldehyde builds up. Naltrexone (A) is an alcohol antagonist that reduces alcohol cravings. Diazepam (C) is a benzodiazepine used for anxiety and alcohol withdrawal symptoms. Morphine (D) is an opioid analgesic and not used for causing a noxious reaction to alcohol.