Triazole Antifungal
Pregnancy: Avoid — teratogenic in animal studies; insufficient human data
Voriconazole
Brand names: Vfend
Adult dose
Dose: IV: loading 6 mg/kg every 12h × 2 doses, then 4 mg/kg every 12h. Oral: ≥40 kg: 400 mg BD (day 1) then 200 mg BD. <40 kg: 200 mg BD loading then 100 mg BD
Route: IV infusion (over 1–3h) or oral
Frequency: BD
Max: 4 mg/kg every 12h IV; 400 mg BD oral
For invasive aspergillosis (first-line), candida infections resistant to fluconazole, rare moulds. Oral bioavailability 96% — switch IV to oral when appropriate. IV formulation contains sulfobutyl-ether-beta-cyclodextrin (SBECD) — accumulates in renal failure, use oral route if eGFR <50.
Paediatric dose
Dose: 8 mg/kg
Route: IV or oral
Frequency: BD (maintenance)
Max: 350 mg BD
Concentration: 10 mg/ml
BNF for Children: loading 9 mg/kg IV every 12h × 2 doses (day 1), then maintenance 8 mg/kg IV every 12h (max 350 mg BD). Calculator uses maintenance dose 8 mg/kg. Children 12–14 yr and ≥50 kg: adult doses. TDM mandatory (target trough 1–5.5 mg/L). Source: BNF for Children 2024; ESCMID/ECMM/ERS Aspergillosis Guidelines 2017
Dose adjustments
Renal
IV: avoid if eGFR <50 (SBECD accumulation — use oral). Oral: no dose adjustment required.
Hepatic
Dose reduce in hepatic impairment — hepatically metabolised
Paediatric weight-based calculator
BNF for Children: loading 9 mg/kg IV every 12h × 2 doses (day 1), then maintenance 8 mg/kg IV every 12h (max 350 mg BD). Calculator uses maintenance dose 8 mg/kg. Children 12–14 yr and ≥50 kg: adult doses. TDM mandatory (target trough 1–5.5 mg/L). Source: BNF for Children 2024; ESCMID/ECMM/ERS Aspergillosis Guidelines 2017
Clinical pearls
- TDM mandatory in paediatrics and recommended in adults — target trough 1–5.5 mg/L
- Visual disturbances: transient photopsia on initiation — usually resolves within hours; warn patients not to drive for 1h after each dose
- Sun protection: significant phototoxicity and long-term SCC risk — sunscreen and protective clothing mandatory
- Oral bioavailability 96% — prefer oral route in stable patients
Contraindications
- CYP3A4 substrates: sirolimus (contraindicated), terfenadine, astemizole, pimozide, quinidine, rifampicin
- IV formulation: eGFR <50
Side effects
- Visual disturbances (photopsia, blurred vision — very common, transient)
- Photosensitivity and phototoxicity (use sun protection)
- Hepatotoxicity (monitor LFTs)
- QT prolongation
- Hallucinations (rare but reported)
- Squamous cell carcinoma risk (long-term phototoxicity)
- Fluorosis and periostitis (prolonged use, paediatric)
Interactions
- CYP2C19/CYP2C9/CYP3A4 substrate and inhibitor — massive interactions
- Warfarin — up to 4-fold increase in INR (halve warfarin, close monitoring)
- Tacrolimus/ciclosporin — levels trebled — reduce dose by 1/3 (tacrolimus) or half (ciclosporin)
- Statins — increased myopathy risk
- Rifampicin, carbamazepine, phenytoin — reduce voriconazole efficacy dramatically
Monitoring
- LFTs (at least weekly during treatment)
- Trough voriconazole levels
- ECG (QT interval)
- Visual assessments
- Signs of phototoxicity
Reference: BNFc; BNF; ESCMID/ECMM/ERS Aspergillosis Guidelines 2017; IDSA Aspergillosis Guidelines. Verify against your local formulary and the latest BNF before prescribing.
Related
Curated clinical cross-links plus same-class fallbacks.
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Pathways