Voriconazole inhibits the fungal CYP51 enzyme (14-alpha demethylase) in ergosterol biosynthesis. One clinically important adverse effect unique to voriconazole among azole antifungals is:
- A Transient visual disturbances (photopsia, altered colour perception, blurring) occurring in up to 30% of patients ✓
- B Peripheral neuropathy due to pyridoxine antagonism
- C Irreversible eighth cranial nerve toxicity
- D Dose-dependent QTc prolongation leading to torsades de pointes
Explanation
Voriconazole uniquely causes visual disturbances — photopsia (flickering, intensified colours, altered visual perception) — in up to 30% of patients, typically within 30 minutes of dosing and resolving within an hour. The mechanism involves voriconazole's effect on the electroretinogram, with transient alteration of photoreceptor function. It is reversible and rarely necessitates discontinuation. Long-term voriconazole use (>6 months) also carries risk of squamous cell carcinoma of the skin (phototoxicity-mediated) — a unique concern among antifungals. QTc prolongation is more relevant to other azoles (fluconazole).
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.