Specimen Collection

Tubes containing gel (SST and PST) are NOT acceptable

Please state dose, dose interval and time of last dose on request form.

0.5 mL Paediatric Plain Blood (Always Required)

Red top plain tubes are the only acceptable paediatric tubes.

4 mL Adult Plain Blood (Preferred)

4 mL Heparin Blood

Please note only DARK GREEN tubes are acceptable, LIGHT GREEN tubes with gel (PST) is NOT acceptable.

Reference Intervals

VORICONAZOLE

Trough >1.0 - 2.0 mg/L for established disease

Trough <5 mg/L to avoid to minimise risk of neurotoxicity

UoM: 7%

Turnaround Time: Between 1 day and 4 days
Assay Method

Platform: HPLC with photodiode aray detection

Diagnostic Use and Interpretation

Voriconazole is a triazole antifungal agent for use in treating invasive aspergillosis, severe candidiasis and some other fungal infections. It is a restricted medication and approval is required for use.

The oral bioavailability is high at about 96%. Absorption is affected by food, particularly a fatty meal, but not by changes in gastric pH.

Voriconazole is metabolised by the hepatic cytochrome P450 isoenzymes, CYP2C19, CYP2C9 and CYP3A4.

The inter-individual variability of voriconazole pharmacokinetics is high due to polymorphisms in the cytochrome CYP2CIP-encoding gene which alter clearance rates.

Clearance is saturable and voriconazole levels may not follow dosage adjustments.

Steady state is achieved in less than 7 days

Voriconazole levels are less predictable in children and for this reason therapeutic drug monitoring is recommended.

Reference

Therapeutic drug monitoring (TDM) of antifungal agents: guidelines from British Society for Medical Mycology. J Microbial Chemotherapy 2014; 69: 1162-1176

Chau MM, Kong DCM, van Hak SJ et al. Consensus guidelines for optimisong antifungal drug delivery and monitoring to avoid toxicity and improve outcomes in patients with haematological malignancy. Int Med J. 2014; 44: 1364-88.

Contact Information

Dr Sally Roberts, Clinical Microbiologist: ext 22705 mobile: 021 674 140

Specimen Transport Instructions for Referring Laboratories

Instructions for Referral to Labplus
Specimen collection	Do NOT use gel tubes
Specimen	Adult: 4mL Red top plain/ Lith Hep with no gel Paed: 0.5mL Red top plain
Aliquot Instructions	Centrifuge and aliquot 1 mL (refrigerate)
Aliquot Transport to Labplus	Refrigerate and transport at 4 o C

Last updated at 16:20:06 08/12/2023