Antifungal and Antiviral Drugs (Antiretrovirals) MCQs

Pharmacology · 98 free questions with answers & explanations.

1. Amphotericin B causes nephrotoxicity primarily through which mechanism?
2. Tenofovir disoproxil fumarate (TDF) causes renal toxicity in some HIV patients. The specific renal syndrome associated with TDF toxicity is:
3. Oseltamivir (Tamiflu) is effective against influenza if started within 48 hours of symptom onset. Its mechanism is:
4. Voriconazole demonstrates nonlinear (zero-order) pharmacokinetics at therapeutic doses. What is the clinical implication and the hepatic enzyme responsible?
5. Tenofovir alafenamide (TAF) was developed to replace tenofovir disoproxil fumarate (TDF) in HIV treatment. What pharmacokinetic advantage does TAF have over TDF that reduces nephrotoxicity and bone toxicity?
6. In HIV management, integrase strand transfer inhibitors (INSTIs) like dolutegravir are preferred as first-line agents over efavirenz (NNRTI). The specific enzymatic step inhibited by INSTIs is:
7. Isavuconazole is a newer broad-spectrum triazole active against both Aspergillus and Mucor species. Compared to voriconazole, it has important clinical advantages EXCEPT:
8. Fluconazole resistance in Candida species most commonly occurs via upregulation of which efflux transporter?
9. Dolutegravir is preferred over first-generation integrase strand transfer inhibitors (raltegravir/elvitegravir) for HIV treatment because:
10. Tenofovir alafenamide (TAF) has replaced tenofovir disoproxil fumarate (TDF) in HIV regimens primarily because:
11. Echinocandins (caspofungin, micafungin, anidulafungin) are fungicidal against Candida but fungistatic against Aspergillus despite inhibiting the same enzyme. The reason for species-dependent fungicidal vs. fungistatic activity is:
12. Lenacapavir, the first long-acting injectable antiretroviral given every 6 months, inhibits HIV replication at multiple stages by targeting which HIV protein?
13. Posaconazole is preferred over fluconazole for prophylaxis of invasive fungal infections in neutropenic patients due to broader spectrum. The pharmacokinetic limitation of the oral suspension form of posaconazole that makes it less reliable in febrile neutropenic patients is:
14. A patient on fluconazole for oesophageal candidiasis is noted to have a significantly elevated INR while also taking warfarin. The mechanism of this interaction is:
15. Tenofovir disoproxil fumarate (TDF) causes nephrotoxicity through which specific tubular mechanism, and which newer formulation reduces this risk?
16. Dolutegravir (DTG), an integrase strand transfer inhibitor (INSTI), has a superior resistance barrier compared to first-generation raltegravir. This is because:
17. Isavuconazole is a newer triazole approved for invasive aspergillosis and mucormycosis. Compared to voriconazole, its pharmacological advantages include:
18. Bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF) is the preferred first-line ART regimen. Tenofovir alafenamide (TAF) has improved renal and bone safety compared to tenofovir disoproxil fumarate (TDF) because:
19. Isavuconazole (isavuconazonium sulfate) is a newer triazole used for aspergillosis. How does it differ from voriconazole in its CYP enzyme pharmacokinetics?
20. Tenofovir alafenamide (TAF) replaced tenofovir disoproxil fumarate (TDF) in HIV regimens. Which pharmacokinetic property explains TAF's lower renal and bone toxicity at 10-fold lower doses?
21. Echinocandins (caspofungin, micafungin, anidulafungin) inhibit beta-1,3-glucan synthase. Which organism is INTRINSICALLY resistant to echinocandins, and what is the biochemical basis?
22. Bictegravir/emtricitabine/tenofovir alafenamide (B/F/TAF) is preferred over older regimens. TAF (tenofovir alafenamide) has significantly lower bone and kidney toxicity compared to TDF (tenofovir disoproxil fumarate) because:
23. A patient on fluconazole for systemic candidiasis does not respond after 5 days. MIC testing shows fluconazole MIC of 32 mcg/mL (resistant). The most common molecular mechanism of this acquired azole resistance in Candida albicans is:
24. Isavuconazole is preferred over voriconazole in invasive mucormycosis combined with invasive aspergillosis because:
25. Dolutegravir is preferred over raltegravir in first-line HIV treatment because of its resistance profile. The primary resistance mechanism relevant to this choice is:
26. Sofosbuvir-based regimens for HCV treatment achieve high cure rates with low resistance because sofosbuvir's NS5B target has a structural constraint limiting mutations. The specific mechanism is:
27. Isavuconazole has pharmacokinetic advantages over voriconazole for invasive mold infections. The mechanism of improved PK predictability of isavuconazole is:
28. Dolutegravir is preferred over raltegravir as an integrase strand transfer inhibitor (INSTI) in second-line ART regimens. The pharmacological basis for dolutegravir's superiority against INSTI-resistant HIV is:
29. Amphotericin B deoxycholate causes significant nephrotoxicity. Lipid formulations of amphotericin B (liposomal amphotericin B — L-AmB) reduce nephrotoxicity by which mechanism?
30. Isavuconazole is preferred over voriconazole in some centres for invasive aspergillosis. The key pharmacological advantage relates to which property?
31. Bictegravir is a component of a single-tablet HIV regimen (B/F/TAF). As an integrase strand transfer inhibitor (INSTI), its advantage over first-generation INSTIs (raltegravir, elvitegravir) includes:
32. Isavuconazole has pharmacokinetic advantages over voriconazole for invasive mold infections. Which specific voriconazole pharmacokinetic limitation does isavuconazole overcome?
33. Dolutegravir (DTG) has a higher genetic barrier to HIV resistance than raltegravir and elvitegravir. Which molecular feature of dolutegravir's integrase binding explains this?
34. Letermovir is used for prophylaxis against cytomegalovirus (CMV) in allogeneic stem cell transplant recipients. Its mechanism of action is unique among antivirals. What is its target?
35. Amphotericin B is fungicidal due to its mechanism of forming membrane pores. The specific interaction enabling this is:
36. In HIV pharmacology, dolutegravir (an integrase strand transfer inhibitor) has a higher genetic barrier to resistance compared to first-generation raltegravir because:
37. Oseltamivir (Tamiflu) for influenza acts by inhibiting neuraminidase. The clinical consequence of untreated neuraminidase activity is:
38. Echinocandins (e.g., caspofungin) are active against Candida but not Cryptococcus neoformans. The reason is:
39. Isavuconazole (ISVZ) was developed as an alternative to voriconazole for invasive aspergillosis. Its pharmacological advantage regarding pharmacokinetics is:
40. A patient on HIV treatment with tenofovir alafenamide (TAF) switches from tenofovir disoproxil fumarate (TDF). The key nephroprotective difference is due to:
41. Echinocandins (caspofungin, micafungin, anidulafungin) are fungicidal against Candida species but only fungistatic against Aspergillus. This difference is because:
42. Tenofovir alafenamide (TAF) has largely replaced tenofovir disoproxil fumarate (TDF) in HIV regimens because:
43. Which antifungal drug is associated with the 'lipid formulation' strategy (liposomal amphotericin B, ABLC) to reduce nephrotoxicity, and what is the mechanism of this toxicity reduction?
44. Oseltamivir (Tamiflu) treats influenza by inhibiting viral neuraminidase. The consequence of this inhibition on viral spread is:
45. Voriconazole is preferred over fluconazole for invasive Aspergillus infections. Compared to fluconazole, voriconazole has extended spectrum because it inhibits:
46. Tenofovir alafenamide (TAF) is preferred over tenofovir disoproxil fumarate (TDF) in HIV-positive patients with renal disease. The pharmacokinetic reason is:
47. Oseltamivir (Tamiflu) treats influenza by which mechanism?
48. Voriconazole is a triazole antifungal used for invasive aspergillosis. Unlike fluconazole, it inhibits both lanosterol 14-alpha demethylase AND which other enzyme, accounting for its broader spectrum?
49. Tenofovir alafenamide (TAF) has replaced tenofovir disoproxil fumarate (TDF) in HIV regimens because TAF achieves higher intracellular drug concentrations with 10-fold lower plasma levels. What accounts for this pharmacokinetic advantage?
50. A patient with HIV develops immune reconstitution inflammatory syndrome (IRIS) after starting antiretroviral therapy (ART). The regimen includes efavirenz. Efavirenz's characteristic CNS side effects (vivid dreams, dizziness) are primarily due to its action on:
51. Amphotericin B deoxycholate is the gold standard antifungal for invasive aspergillosis before liposomal formulations were introduced. Its mechanism of action is:
52. Tenofovir disoproxil fumarate (TDF), a key component of HIV HAART regimens, can cause proximal renal tubular dysfunction (Fanconi syndrome). The mechanism is:
53. Acyclovir is used for herpes simplex encephalitis. It is selectively phosphorylated in HSV-infected cells. Which viral enzyme accomplishes the first, rate-limiting phosphorylation step?
54. Oseltamivir (Tamiflu) is used for influenza A and B. Its mechanism of action is:
55. Amphotericin B exerts its antifungal effect by a mechanism distinct from azoles. It acts by:
56. Tenofovir disoproxil fumarate (TDF) is a nucleotide reverse transcriptase inhibitor (NtRTI). Its mechanism differs from nucleoside analogues (NRTIs) because:
57. Voriconazole is preferred over fluconazole for invasive aspergillosis. The structural feature of Aspergillus that makes it intrinsically resistant to fluconazole but susceptible to voriconazole is:
58. Oseltamivir (Tamiflu) must be given within 48 hours of influenza symptom onset to be effective. The pharmacological basis is:
59. Dolutegravir (an integrase strand transfer inhibitor, INSTI) is preferred as first-line ART over older INSTIs (raltegravir) because:
60. Acyclovir is highly selective for HSV/VZV-infected cells over uninfected cells. The basis for this selectivity is:
61. A 35-year-old HIV patient with a CD4 count of 80 cells/mm3 develops CNS cryptococcosis. After induction with liposomal amphotericin B and flucytosine, he is started on oral fluconazole maintenance. Flucytosine exerts antifungal activity through a unique mechanism. After entering fungal cells via cytosine permease, it is converted to:
62. A patient with HIV is started on tenofovir alafenamide (TAF) rather than tenofovir disoproxil fumarate (TDF). The switch is made primarily because TAF:
63. Amphotericin B causes nephrotoxicity by a specific mechanism distinct from its antifungal action. The nephrotoxic mechanism is:
64. Integrase strand transfer inhibitors (INSTIs — raltegravir, dolutegravir, bictegravir) are now preferred first-line ARV agents. Dolutegravir's advantage over first-generation raltegravir includes:
65. Voriconazole inhibits the fungal CYP51 enzyme (14-alpha demethylase) in ergosterol biosynthesis. One clinically important adverse effect unique to voriconazole among azole antifungals is:
66. Amphotericin B is nephrotoxic. Its antifungal mechanism, which also explains its toxicity, is:
67. A patient with HIV/AIDS on first-line HAART develops peripheral neuropathy, lactic acidosis, and hepatic steatosis. The antiretroviral class most likely responsible is:
68. Oseltamivir is used for influenza treatment and prophylaxis. Its mechanism of action is:
69. Amphotericin B and azole antifungals both target ergosterol in the fungal cell membrane but differ fundamentally in their mechanism. Which statement accurately distinguishes them?
70. Dolutegravir is preferred over raltegravir/elvitegravir in antiretroviral therapy because of its higher genetic barrier to resistance. The target of all integrase strand transfer inhibitors (INSTIs) is:
71. A patient with relapsed/refractory hepatitis C genotype 1 is prescribed sofosbuvir/ledipasvir. Sofosbuvir's mechanism of action and the specific step it targets in HCV replication is:
72. A patient with HIV on ART (TDF + FTC + efavirenz) has an undetectable viral load but develops persistent virological failure (VL >1000 copies/mL) after 2 years. Resistance testing shows K65R mutation. This mutation causes resistance to:
73. Amphotericin B deoxycholate causes nephrotoxicity. Which newer formulation MOST significantly reduces nephrotoxicity while maintaining antifungal efficacy?
74. Oseltamivir (Tamiflu) inhibits viral neuraminidase. What is the consequence if neuraminidase is NOT inhibited?
75. Amphotericin B has the highest efficacy among systemic antifungals but significant nephrotoxicity. Which formulation strategy reduces nephrotoxicity while maintaining antifungal efficacy?
76. Integrase strand transfer inhibitors (INSTIs) such as raltegravir and dolutegravir represent a key antiretroviral drug class. They inhibit HIV replication at which specific step?
77. Echinocandins (caspofungin, micafungin, anidulafungin) are fungicidal against Candida and fungistatic against Aspergillus. Their mechanism is:
78. Dolutegravir (DTG) is preferred in first-line HIV regimens over older integrase strand transfer inhibitors (INSTIs). Which property makes DTG superior in terms of resistance?
79. A patient with AIDS develops disseminated Cryptococcus neoformans meningitis. The induction regimen per current guidelines combines amphotericin B with flucytosine. Flucytosine exerts its antifungal effect by:
80. Integrase strand transfer inhibitors (INSTIs) like dolutegravir are preferred first-line ART components. Their mechanism of action involves:
81. Amphotericin B causes nephrotoxicity via a direct tubular mechanism. The strategy of using liposomal amphotericin B (L-AmB) reduces nephrotoxicity because:
82. Dolutegravir, an HIV integrase strand transfer inhibitor (INSTI), is preferred over first-generation raltegravir in highly treatment-experienced patients because:
83. Voriconazole is the preferred treatment for invasive aspergillosis. Its mechanism differs from fluconazole in that voriconazole is active against Aspergillus because:
84. A patient with AIDS and cryptococcal meningitis is treated with amphotericin B. Liposomal amphotericin B (AmBisome) is preferred over conventional amphotericin B deoxycholate because:
85. A patient on tenofovir alafenamide (TAF)-based ART regimen has significantly less renal and bone toxicity compared to tenofovir disoproxil fumarate (TDF). The pharmacological basis for this differential toxicity profile is:
86. Amphotericin B causes nephrotoxicity as its major dose-limiting adverse effect. Liposomal amphotericin B (L-AMB) was developed to reduce this toxicity while maintaining antifungal efficacy. What is the molecular basis for L-AMB's improved renal safety profile?
87. A 30-year-old HIV-positive patient on tenofovir alafenamide (TAF)-based regimen is switched from tenofovir disoproxil fumarate (TDF) due to declining eGFR. What is the pharmacokinetic rationale for TAF's improved renal and bone safety compared to TDF?
88. Echinocandins (caspofungin, micafungin, anidulafungin) are fungicidal against Candida but fungistatic against Aspergillus. What structural and cellular difference between these organisms explains this distinction?
89. Echinocandins (caspofungin, micafungin, anidulafungin) are first-line for invasive candidiasis. Their mechanism differs fundamentally from other antifungals. Which statement accurately describes echinocandin resistance in Candida glabrata?
90. Dolutegravir is preferred over older integrase inhibitors (raltegravir, elvitegravir) for HIV treatment. The resistance barrier advantage of dolutegravir relates to which mechanism?
91. Sofosbuvir is a nucleotide analogue inhibitor of HCV NS5B RNA-dependent RNA polymerase used in HCV DAA regimens. Its pan-genotypic activity and resistance profile is explained by:
92. Amphotericin B causes nephrotoxicity despite the fact that ergosterol (not cholesterol) is its primary membrane target. The mechanism of nephrotoxicity is:
93. Voriconazole differs from fluconazole in its spectrum and pharmacokinetics. Which feature is unique to voriconazole among triazoles?
94. Dolutegravir is preferred over raltegravir as an HIV integrase inhibitor. The key pharmacological advantage of dolutegravir is:
95. Amphotericin B is selectively toxic to fungi compared with mammalian cells because it:
96. Integrase strand transfer inhibitors (INSTIs, e.g., dolutegravir) are preferred agents in first-line HIV ART regimens because:
97. Integrase strand transfer inhibitors (INSTIs) like dolutegravir act at which step of the HIV replication cycle?
98. Voriconazole is preferred over fluconazole for invasive Aspergillus infections because: