Isavuconazole is preferred over voriconazole in some centres for invasive aspergillosis. The key pharmacological advantage relates to which property?

• A Isavuconazole is a prodrug (isavuconazonium sulfate) with linear pharmacokinetics and fewer CYP3A4 interactions compared to voriconazole's non-linear pharmacokinetics
• B Isavuconazole inhibits ergosterol synthesis more potently with lower MICs for Aspergillus
• C Isavuconazole has better CNS penetration for cerebral aspergillosis due to P-glycoprotein inhibition
• D Isavuconazole is active against Mucorales (unlike voriconazole) and has predictable linear PK with fewer photosensitivity and visual disturbance adverse effects ✓

Explanation

Isavuconazole (prodrug isavuconazonium sulfate, converted to isavuconazole by plasma esterases) is active against Aspergillus spp. AND Mucorales (mucormycosis), making it the only triazole with dual activity — voriconazole lacks activity against Mucor/Rhizopus. Isavuconazole shows linear, predictable pharmacokinetics unlike voriconazole's non-linear PK and genetic variability (CYP2C19 polymorphism), and lacks voriconazole's visual disturbances, photosensitivity, periostitis, and fluorosis adverse effects. Voriconazole has better clinical evidence for first-line Aspergillus treatment but isavuconazole is preferred in patients intolerant to voriconazole or with mucormycosis risk.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

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