Posaconazole, Serum
Use
Posaconazole is a triazole antifungal agent used primarily for prophylaxis of invasive Aspergillus and Candida infections in severely immunocompromised patients, such as those with prolonged neutropenia or hematopoietic stem cell transplant recipients. It is also indicated for the treatment of oropharyngeal candidiasis, including cases refractory to other antifungals. Therapeutic drug monitoring of posaconazole helps in ensuring adherence to targeted serum concentrations essential for therapeutic efficacy and preventing subtherapeutic exposure, which could potentially lead to treatment failure.
Special Instructions
Therapeutic drug monitoring is recommended to document optimal absorption, particularly when posaconazole is used for prophylaxis or treatment of fungal infections. Consider rechecking posaconazole levels in patients with poor nutritional intake, receiving continuous tube feeding, or on proton pump inhibitors, as these conditions can affect drug absorption.
Limitations
Posaconazole absorption can be variable, and its bioavailability is influenced by food intake. Inadequate absorption can occur during fasting, leading to insufficient plasma concentrations. Additionally, conditions like mucositis or diarrhea can impact absorption. Drug interactions with proton pump inhibitors and continuous feeding can further complicate adequate drug monitoring. Despite these limitations, a toxic range for posaconazole serum levels has not been established, and therapeutic levels should be assessed considering clinical context.
New York Approved
Methodology
Mass Spectrometry (LC-MS/MS)
Biomarkers
LOINC Codes
- 53731-6
- 53731-6
Result Turnaround Time
2-5 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
2 mL
Minimum Volume
0.6 mL
Container
Plastic vial
Collection Instructions
Within 2 hours of collection, centrifuge and aliquot serum into a plastic vial.
Causes for Rejection
Only severe conditions like gross hemolysis, lipemia, and icterus are acceptable, but ideally minimized.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 28 days |
| Refrigerated | 28 days |
| Frozen | 28 days |