What is the drug of choice for ringworm infection?:

Correct Answer: A

Rationale: The correct answer is A: Griseofulvin. Griseofulvin is the drug of choice for ringworm infection because it specifically targets the fungus that causes ringworm. It works by inhibiting fungal cell division, leading to the destruction of the fungus. Amphotericin B is an antifungal medication used for systemic fungal infections, not for ringworm. Nystatin is used to treat fungal infections of the skin, mouth, and intestines, but it is not the first-line treatment for ringworm. Neomycin is an antibiotic used to treat bacterial infections, not fungal infections like ringworm. Therefore, Griseofulvin is the most appropriate choice for treating ringworm.

Correct Answer: C

Rationale: The correct answer is C: Amantadine. Amantadine is an antiviral medication that is specifically effective against influenza A virus. It works by blocking the viral ion channel, preventing the virus from entering the host cell. This inhibits viral replication and helps reduce the severity and duration of symptoms. Choice A, Cidofovir, is used to treat certain DNA viruses but is not effective against influenza A. Choice B, Famciclovir, is used to treat herpes viruses, not influenza A. Choice D, Ribavirin, is an antiviral medication used for respiratory syncytial virus and hepatitis C, but not as effective against influenza A. Therefore, the most appropriate choice in this scenario is Amantadine due to its specific activity against influenza A virus.

Correct Answer: D

Rationale: Rationale for choice D: Retroviral protease inhibitors, such as lopinavir and ritonavir, are correct because they are more active in inhibiting HIV replication than zidovudine (B) and they inhibit CYP 3A4 and interact with many other drugs (C). Explanation for why other choices are incorrect: A: Retroviral protease inhibitors do not act at an early step in HIV replication; they act by blocking the protease enzyme necessary for viral maturation. B: Zidovudine is a nucleoside reverse transcriptase inhibitor, not a protease inhibitor, so retroviral protease inhibitors are more potent against HIV. C: While retroviral protease inhibitors do inhibit CYP 3A4 and interact with other drugs, this statement alone does not capture the complete picture of their mechanism of action or potency compared to zidovudine.

Correct Answer: D

Rationale: The correct answer is D: Piperazine. Piperazine is a paralytic agent that causes relaxation of the muscles of the roundworm (Ascaris), allowing it to be easily expelled from the intestine. By administering piperazine via orogastric tube, the clumped roundworms causing intestinal obstruction can be relaxed, relieving the obstruction. Levamisole, Mebendazole, and Pyrantel pamoate are not effective in relaxing the muscles of the roundworms, making them incorrect choices for this specific scenario.

Correct Answer: D

Rationale: The correct answer is D because using antibiotic combinations covering both gram positive and gram negative bacteria can disrupt the balance of normal flora in the body, leading to superinfections. Gram positive and gram negative bacteria have different susceptibility patterns, so using a combination of antibiotics increases the likelihood of killing off a wider range of bacteria, including the beneficial ones. This disruption paves the way for opportunistic pathogens to overgrow and cause superinfections. Choices A, B, and C are incorrect because narrow spectrum antibiotics target specific bacteria, short courses of antibiotics reduce the risk of resistance and overgrowth, and antibiotics completely absorbed from the small intestines have minimal impact on gut flora compared to systemic antibiotics.