Sample type: Serum

Test name: Voriconazole

Condition / Indication: Voriconazole assay is useful, at least initially, in most patients as it has unpredictable pharmacokinetics based on the presence and activity of metabolic enzymes which vary according to the individual. On switching from the IV to oral formulations assay may be helpful to confirm therapeutic levels are maintained. Assay is indicated in patients failing to respond to therapy and may be helpful in patients with gastrointestinal dysfunction receiving therapy with proton pump inhibitors to confirm optimal oral absorption.

Advance warning: Not normally required during our core working hours (Mon – Fri 09:00 – 17:15). Please contact laboratory to discuss the possibility of this assay being performed on Saturdays, Sundays and Bank Holidays.

Sample required: Approx. 1-2mL of separated serum (the minimum acceptable is 100µL). It is best to use a plain clotted blood tube (red top) for collection but if a gel tube (gold top) is used it is important for the requesting laboratory to separate off the serum from this primary gel tube into a secondary tube as soon as possible. This is because the gel may bind the analyte which may result in an artificially lower result being obtained, interpreted and reported.
Samples may be sent by post. Transport time must be <4 weeks. Samples should be kept at 4°c if there is a delay in sending. Please contact laboratory if in doubt as sample integrity may be affected. Samples must be sealed and packed to conform to current regulations. Leaking samples may not be processed.

Timing of samples: We recommend a pre dose sample taken immediately before administration

Test information required: • Patient name, sex and age
• Laboratory number
• Dosage, frequency and timing of samples
• Clinical Summary
• Other medications (essential)
• Address for report
• Phone (fax if preferred) number for report or email address for an electronic copy
• Contact name
• Appropriate hazard warnings

Results: Results will be telephoned/faxed or emailed on the day of receipt for samples received between 9 am and 3 pm Monday to Friday. A written confirmation report will be sent by post.

Reference range: Prophylaxis and therapy – Pre dose 1.0-5.5mg/L or 2.0-5.5 mg/L for bulky or disseminated infections.

Container: Serum Red top tube

Alternative container: Serum Gold top tube, however ensure the serum is separated off into a primary tube as soon as possible (see Sample Required section).

Referred outside NBT for analysis? No

Discipline: Antimicrobial Reference Laboratory

Turnaround time: <3 days

Re-assay interval: 4-8 Days – Assuming initial results are within expected range.