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ANTIINFECTIVES FOR SYSTEMIC USE › ANTIMYCOTICS FOR SYSTEMIC USE › ANTIMYCOTICS FOR SYSTEMIC USE › Triazole and tetrazole derivatives
voriconazole
J02AC03
Forms & Strengths
- Tablet: 50 mg, 200 mg
- Powder for oral suspension: 40 mg/mL
- Powder for injection, lyophilized: 200 mg per vial
Adult Dosing
- Invasive aspergillosis / Candidemia: Loading dose 6 mg/kg IV q12h for 24 hours, then maintenance 4 mg/kg IV q12h or 200-300 mg PO q12h
- Esophageal candidiasis: 200 mg PO q12h (patients > 40 kg)
- Adjustment for oral switch: 200 mg PO q12h if < 40 kg; 300 mg PO q12h if >= 40 kg
Pediatric Dosing
- Ages 2 to < 12 years: Loading dose 9 mg/kg IV q12h for 24 hours, then maintenance 8 mg/kg IV q12h; oral suspension 9 mg/kg (max 350 mg) q12h
- Ages 12-14 years with < 50 kg: 9 mg/kg IV loading, then 7 mg/kg IV q12h or 200 mg PO q12h
- Ages 12-14 years with >= 50 kg: standard adult dosing
Indications
- Treatment of invasive aspergillosis
- Treatment of candidemia in non-neutropenic patients and disseminated candidiasis in skin and abdomen/kidney/bladder wall
- Treatment of severe refractory fungal infections due to Scedosporium apiospermum and Fusarium species
- Salvage therapy for fluconazole-refractory serious invasive fungal infections
Mechanism of Action
- Triazole antifungal agent that inhibits fungal cytochrome P450-mediated 14-alpha-lanosterol demethylation
- Blocks ergosterol biosynthesis, leading to accumulation of 14-alpha-methylsterols and disruption of fungal cell membrane integrity
Contraindications
- Co-administration with CYP3A4 substrates that prolong QT interval (e.g., pimozide, quinidine, ivabradine)
- Co-administration with CYP3A4 inducers (rifampin, ritonavir high doses, carbamazepine, long-acting barbiturates, St. John's wort)
- Co-administration with sirolimus (due to significant pharmacokinetic interaction)
- Hypersensitivity to voriconazole or excipients
Adverse Reactions
- Visual disturbances (photopsia, blurred vision, chromatopsia) in up to 30% of patients
- Hepatotoxicity (elevated transaminases, jaundice, severe hepatic failure)
- Dermatological reactions (photosensitivity, rash, squamous cell carcinoma with long-term use)
- QT prolongation and electrolyte disturbances
- Peripheral neuropathy
Drug Interactions
- Strong inhibitor and substrate of CYP2C19, CYP2C9, and CYP3A4, leading to numerous significant drug-drug interactions
- Increases plasma concentrations of calcineurin inhibitors (cyclosporine, tacrolimus); dose reduction required
- Enhances anticoagulant effect of warfarin, requiring close monitoring of INR
- May increase serum concentrations of statins (e.g., atorvastatin, lovastatin), increasing risk of rhabdomyolysis
- Concomitant use with strong CYP3A4 inducers significantly decreases voriconazole plasma concentrations and efficacy
Curated Content: Needs Vetting Before Put to Clinical Use