Voriconazole Dosing in Invasive Aspergillosis with Renal Impairment

Critical Distinction: IV vs. Oral Formulation

The Infectious Diseases Society of America recommends that in patients with impaired renal function, oral voriconazole should be used instead of intravenous formulation, with standard dosing of 400 mg (6 mg/kg) twice daily for 2 loading doses, followed by 200 mg twice daily maintenance—no renal dose adjustment is required for oral voriconazole 1, 2
The IV formulation contains sulfobutyl-ether cyclodextrin vehicle that accumulates in patients with creatinine clearance <50 mL/min, and its accumulation consequences remain uncertain 1
IV voriconazole is not recommended for patients with CrCl <50 mL/min due to potential cyclodextrin toxicity 2

The standard loading dose is 400 mg (6 mg/kg) orally twice daily for 2 doses on day 1, which is critical for rapidly achieving therapeutic levels 3, 2
The standard maintenance dose is 200 mg orally twice daily, which can be increased to 300 mg twice daily if inadequate response 3, 4, 2

The minimum duration of therapy for invasive aspergillosis is 6-12 weeks, and it should be continued throughout the period of immunosuppression until lesions resolve 4

Therapeutic drug monitoring is recommended due to high interpatient variability, especially with oral therapy, and CYP2C19 polymorphisms cause wide variability in serum levels 2, 1, 2
Review all concurrent medications for potentially deleterious interactions, as voriconazole inhibits CYP2C19, CYP2C9, and CYP3A4 1, 2

Voriconazole demonstrated superior outcomes versus amphotericin B, with 53% vs 32% successful response, and 71% vs 58% survival at 12 weeks, making it the first-line agent for invasive aspergillosis 3, 4

Never use IV voriconazole in patients with CrCl <50 mL/min unless absolutely no alternative exists, as recommended by the Infectious Diseases Society of America 1, 2

If concurrent hepatic impairment (mild to moderate), reduce maintenance dose by 50%, as voriconazole is the only triazole requiring hepatic dose adjustment 2