Master the board step 3

Master the Boards: USMLE Step 3
Basic Science Correlate
Mechanisms of Oral Hepatitis C Medications
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Sofosbuvir: RNA polymerase inhibitor
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Simeprevir, boceprevir, and telaprevir: Protease inhibitors that prevent
viral maturation by inhibiting protein synthesis
Antifungal Agents
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Fluconazole: Candida (not Candida krusei or Candida glabrata), Cryptococcus,
oral and vaginal candidiasis as an alternative to topical mediations
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Itraconazole: Largely equal to fluconazole but less easy to use; rarely the best
initial therapy for anything
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Voriconazole: Covers all Candida; best agent against Aspergillus. Adverse effect:
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Some visual disturbance
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Posaconazole: Also covers mucormycosis or Mucorales
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Echinocandins (caspofungin, micafungin, anidulafungin):
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Excellent for neutropenic fever patients.
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Does not cover Cryptococcus.
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Better than amphotericin for neutropenia and fever (less mortality).
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Adverse effect—Echinocandins have no significant human toxicity because
they affect/inhibit the 1,3 glucan synthesis step, which does not exist in humans.
Basic Science Correlate
Mechanism of Antifungal Medications
Azole antifungals inhibit conversion of lanosterol to ergosterol. Ergosterol
is the major component of the cell wall of fungi. Disrupting ergosterol
damages the cell membrane and increases its permeability, resulting in cell
lysis and death.
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Amphotericin: Effective against all Candida, Cryptococcus, and Aspergillus:
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The last 2 main indications for amphotericin are Cryptococcus and
mucormycosis.
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Aspergillus: Voriconazole superior to amphotericin
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Neutropenic fever: Caspofungin superior to amphotericin
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Candida: Fluconazole is equal to amphotericin for efficacy but has far
fewer adverse effects.
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