Which of the following fungicidal drug that acts by inhibiting fungal squalene * epoxidase enzyme and is the drug of choice for onymycosis of the toe nails in 56 year old woman with diabetes?

Correct Answer: B

Rationale: Rationale: Terbinafine is the correct answer as it inhibits fungal squalene epoxidase, disrupting ergosterol synthesis in the fungal cell membrane. This drug is specifically effective against onychomycosis in diabetic patients due to its fungicidal action and good nail penetration. Griseofulvin (A) targets microtubules, not squalene epoxidase. Itraconazole (C) inhibits ergosterol synthesis via a different mechanism. Amphotericin B (D) disrupts fungal cell membrane by binding to ergosterol, not squalene epoxidase.

Correct Answer: D

Rationale: The correct answer is D: Ritonavir. Ritonavir is a protease inhibitor that works by inhibiting the HIV protease enzyme, which is crucial for viral replication. This action helps prevent the virus from spreading and multiplying in the body. Lamivudine (A), Efavirenz (B), and Stavudine (C) are not protease inhibitors and work through different mechanisms like nucleoside reverse transcriptase inhibition (Lamivudine and Stavudine) and non-nucleoside reverse transcriptase inhibition (Efavirenz). Therefore, they do not directly target the HIV protease enzyme like Ritonavir does.

Correct Answer: A

Rationale: Acyclovir is a nucleoside analog that inhibits viral DNA replication by targeting viral DNA polymerase. Herpes simplex Type 1 virus is most susceptible to acyclovir because it is a DNA virus that requires viral DNA polymerase for replication. The drug is selectively activated by viral thymidine kinase in infected cells, leading to its antiviral activity. Herpes simplex Type 2, Varicella zoster, and other viruses do not possess the same susceptibility to acyclovir due to differences in their replication mechanisms.

Correct Answer: B

Rationale: The correct answer is B: Tinidazole. This drug is used for oral treatment of trichomonas vaginitis due to its high efficacy against the parasite. Tinidazole is a nitroimidazole antibiotic that targets anaerobic organisms like Trichomonas vaginalis. Diiodohydroxyquin (A) is used for amoebiasis, not trichomonas. Clotrimazole (C) and Ketoconazole (D) are antifungal medications and not effective against trichomonas parasites.

Correct Answer: C

Rationale: Step 1: Clofazimine is the correct answer because it is known to suppress both lepra reaction and reversal reaction in leprosy treatment. Step 2: Dapsone is mainly used to treat leprosy but does not specifically target lepra reaction. Step 3: Rifampin is effective against leprosy but does not have a direct impact on lepra reactions. Step 4: Minocycline can be used in leprosy treatment but does not have the same dual action as clofazimine.