Itraconazole Drug Level
Label Mnemonic: ICZ
Epic Lab Code: LAB3453
Downtime Form: A-1a Therapeutic Drug Assay Requisition
Commercial Mail-out Laboratory
5231 RCP
356-8593
Specimen(s):
Serum
Specimen Instructions:
The "Absolute Minimum" listed above, allows for the assay to be performed once. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected; we suggest a full red top for this test to be completed.
Collection Medium:
Red top tube 5 mL (Clot Activator)
Minimum:
Preferred Minimum: 1 mL serum
Absolute Minimum: 0.2 mL serum
Rejection Criteria:
Serum gel tube is not acceptable.
Turn Around Time:
3 days upon receipt at reference laboratory
Reference Range:
Itraconazole (trough): >0.5 mcg/mL (localized infection) >1 mcg/mL (systemic infection) Hydroxyitraconazole: No therapeutic range established; activity and serum concentration are similar to parent drug.
Interpretive Data:
A lower cutoff concentration has not been defined that applies in all cases. The serum concentration must be interpreted in association with other variables, such as the nature of the infection, the specific microorganism, and minimal inhibitory concentration (MIC) results, if available. Localized infections are more likely to respond when serum itraconazole is >0.5 mcg/mL (by HPLC); systemic infections generally require drug concentrations >1.0 mcg/mL.
Comments:
Enteropathy, H2-histamine receptor blockers, hepatic enzyme inducers, and other variables can result in low to nondetectable serum levels with concomitant high risk of therapeutic failure. AIDS patients and organ transplant patients receiving immunosuppressive therapy tend to have lower serum itraconazole levels on standard doses and are thus at high risk of therapeutic failure.
Methodology:
Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
CPT Code:
82542