Voriconazole

Restricted
C. diff Risk

Low

Oral Bioavailability

Excellent

Approximate Cost

IV-$300 PO-$100

Spectrum Of Activity

Dosing

Dosing in infants and children younger than 2 years of age is not well established. Small pharmacokinetic studies show that the same mg/kg dosing may be used if there is no alternative treatment9 mg/kg/dose IV/PO q12h
Maximum : 350 mg/dose
Note: Optimal doses are unknown, but studies have demonstrated children require higher mg/kg doses compared with adults to achieve similar voriconazole exposure.

IV Route PO Route, 0 to 39 kgPO Route, Greater than or equal to 40 kgLoading dose: 6 mg/kg/dose IV q12h X 2 doses then,
Maintenance dose: 4 mg/kg/dose IV q12h(Optional) loading dose: 200 mg PO BID X 2 doses then,
Maintenance dose: 100 mg PO BID(Optional) loading dose: 400 mg PO BID X 2 doses then,
Maintenance dose: 200 mg PO BID

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

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

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)