All of the following is true about Voriconazole except:
**Core Concept**
Voriconazole is a broad-spectrum antifungal medication that belongs to the triazole class. It works by inhibiting the cytochrome P450-dependent enzyme lanosterol 14α-demethylase, which is essential for the conversion of lanosterol to ergosterol in the fungal cell membrane. This action disrupts the fungal cell membrane's integrity and ultimately leads to cell death.
**Why the Correct Answer is Right**
Voriconazole is primarily metabolized by the liver enzyme CYP2C19, and its metabolism is significantly influenced by genetic variations in this enzyme. The correct answer will likely relate to the pharmacokinetics or pharmacodynamics of voriconazole.
**Why Each Wrong Option is Incorrect**
**Option A:** Voriconazole has a narrow therapeutic index, which means it has a small margin between the effective dose and the toxic dose. This is incorrect because voriconazole actually has a relatively wide therapeutic index.
**Option B:** Voriconazole is primarily used to treat invasive aspergillosis. This is incorrect because while voriconazole is effective against aspergillosis, it is also used to treat other fungal infections such as candidemia and esophageal candidiasis.
**Option C:** Voriconazole is contraindicated in patients with liver dysfunction. This is incorrect because while liver dysfunction may require dose adjustments, voriconazole is not contraindicated in patients with liver dysfunction.
**Clinical Pearl / High-Yield Fact**
The CYP2C19 genotype of a patient can significantly affect their voriconazole clearance, with poor metabolizers requiring dose adjustments to avoid toxicity.
**Correct Answer: A. Voriconazole has a narrow therapeutic index.**