Voriconazole

C. diff Risk

Low

Oral Bioavailability

Excellent

Approximate Cost

IV-$300 PO-$100

Spectrum Of Activity

Dosing

In pediatric patients <12 years, bioequivalence between the oral tablet and suspension has not been determined; due to possible shortened gastric transit time in infants and children, absorption of tablets may be different than adults

IV formulation contains sulfobutyl ether beta-cyclodextrin (SBECD) which may accumulate in renal insufficiency.

General Information

Common Usage

Aspergillosis

Drug Monitoring

Therapeutic drug monitoring may be helpful to ensure adequate concentrations and exclude toxicity (discuss with ID). Target trough 1-5 mg/L. Collect in heparinized tube 0-30 minutes prior to dose and send to Toronto Sick Kids for analysis: http://www.sickkids.ca/paediatriclabmedicinems/test-catalogue/TDM/56312.html

Steady state should be achieved after 4-7 days.

*Use IV voriconazole with caution if creatinine clearance <50 mL/min (IV vehicle; SBECD (sulfobutylether-β-cyclodextrin) may accumulate)
Monitor QTc interval in patients at elevated risk
Monitor liver enzymes and bilirubin once weekly for first month and then monthly thereafter.

Adverse Effects

  • QTc prolongation

  • Hepatic enzyme abnormalities

  • Rash - up to 20%

  • Photosensitivity and photoxicity

  • GI upset

  • Visual disturbances may occur

Major Interactions

Many via CYP450- suggest review interactions with pharmacist.
Risk when combining with other QTc prolonging agents

Oral Liquids

Concentration: 40 mg/mL

Not all strengths of oral liquids are listed nor are available on IWK formulary

Tablet/Capsule Strengths

50 mg tablet
200 mg tablet
Tablets and capsules are preferred especially over an unpleasant tasting liquid.
Not all strengths of oral tablets/capsules are listed and they are not all available on the IWK formulary.

Pharmacology

Antimicrobial class: Triazole antifungal, second generation

Average serum half life: Variable and dose dependent.

Route of Elimination: Urine (<2% as unchanged drug)