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Test Update Information Effective June 22, 2016, posaconazole testing will be performed in-house at China Basin Chemistry using a LC-MS/MS method. The therapeutic trough concentration remains the same.

The results of this method are approximately 26% higher than the results from Focus Diagnostics (via Quest).
Approval req'd? No
Available Stat? No
Test code PSCA
Performed by China Basin Chemistry
In House Availability Tuesday and Friday AM (excluding holidays)
Method LC-MS/MS
Collection Instructions In most cases, a single trough level of posaconazole should be adequate. This level should be drawn after at least seven days of posaconazole (steady state is 7-10 days) have been administered.

Posaconazole should be administered with food or nutritional supplement. The level should be drawn from 11-12 hours after the previous dose and less than one hour prior to the next dose. Peak levels should only be drawn in special circumstances.
Container type Red top (Gold top NOT acceptable)
Amount to Collect 2 mL blood
Sample type Serum
Preferred volume 1 mL serum
Min. Volume 0.3 mL serum
UCSF Rejection Criteria Collected in Gold top tube.
Processing notes Refrigerate serum.
Units µg/mL (mcg/mL)
Normal range Therapeutic trough > 0.7 µg/mL

Patient nutritional status (fat intake) at the time of dosing may affect peak serum concentrations.
Synonyms Posanol, Noxafil
Stability Refrigerated: 1 week
Frozen: 6 months
Turn around times 3-4 days.
Additional information Background
Posaconazole is a triazole antifungal agent with potent activity against yeasts and molds. It is considered an alternative treatment for zygomyces, invasive Aspergillus infections, Candida and other infections caused by pathogenic yeasts. Data is insufficient to recommend routine monitoring of posaconazole concentrations in clinical practice but may be considered in certain circumstances.

Indications for Posaconazole TDM
At this time there is insufficient data to recommend routine monitoring of posaconazole levels. Thus, posaconazole TDM should be restricted to use in patients with proven or highly suspected invasive fungal infections, who are anticipated to need the drug for > 14 days, who are currently receiving appropriate doses, and who:

1) have known or suspected gastrointestinal absorption abnormalities and are receiving oral posaconazole

2) are receiving other drugs that would likely have a significant interaction with posaconazole (e.g. phenytoin, rifabutin, carbamezapine) and cannot be discontinued without an adverse effect on patient care

3) are experiencing treatment failure of their fungal infection despite maximal therapy, and where a change to a non-posaconazole-based regimen is not feasible

4) are experiencing substantial hepatic toxicity (AST/ALT > 5 times upper limit of normal or total bilirubin > 3 mg/dl) while on posaconazole, with other potential causes ruled out.
CPT coding 80299
LOINC code 53731-6
LDT or Mod FDA? Yes
Last Updated 6/22/2016 11:34:51 AM
Entry Number 1143
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