Sulfamethoxazole, Serum
Use
Monitoring sulfamethoxazole therapy to ensure drug absorption, clearance, or compliance. Sulfamethoxazole is used in conjunction with trimethoprim to treat various infections, including methicillin-resistant Staphylococcus aureus, and for prophylaxis in immunosuppressed patients, such as those who are HIV positive.
Special Instructions
Serum for a peak level should be collected 60 minutes after dose. Within 2 hours of collection, centrifuge and aliquot serum into a plastic vial. If not ordering electronically, complete, print, and send a Therapeutics Test Request (T831) with the specimen.
Limitations
Specimens collected in serum gel tubes are not acceptable, as the drug can absorb on the gel and lead to falsely decreased concentrations. Therapeutic drug monitoring is indicated only when prolonged (>3 months) therapy is required. Toxicity includes crystalluria with resultant calculi and kidney disease due to high concentration of acetylated, relatively insoluble forms of the drug.
New York Approved
Methodology
Mass Spectrometry (LC-MS/MS)
Biomarkers
LOINC Codes
- 10342-4
- 10342-4
Result Turnaround Time
2-5 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1 mL
Minimum Volume
0.5 mL
Container
Red top (gel tubes/SST are not acceptable); Plastic vial
Collection Instructions
Serum for a peak level should be collected 60 minutes after dose. Within 2 hours of collection, centrifuge and aliquot serum into a plastic vial.
Causes for Rejection
Serum gel tubes; Gross hemolysis: OK; Gross lipemia: OK; Gross icterus: OK.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 28 days |
| Refrigerated | 28 days |
| Frozen | 28 days |