Procainamide, Serum or Plasma
Also known as: Pronestyl®
Use
The test is used to monitor the levels of procainamide and its active metabolite N-acetyl procainamide (NAPA) in patients' blood. Procainamide is used in the treatment of various cardiac arrhythmias. Monitoring is essential as the drug exhibits significant interindividual variability in metabolism, especially influenced by genetic factors. Impaired renal function can significantly alter drug disposition, particularly for NAPA, and prolonged half-life can be observed in geriatric patients.
Special Instructions
Patients should note that the optimal plasma sampling time after oral dosage is one to two hours and after I.V. administration, it is 30 minutes. The drug is rapidly absorbed with peak blood levels generally occurring within an hour of administration. It is crucial not to use a gel-barrier tube for collection, as it may significantly affect drug level measurement due to slow absorption by the gel.
Limitations
The rate of metabolism for procainamide is genetically determined, differentiating patients into slow and fast acetylator types. As such, the test cannot account for all variations due to genetic differences. Furthermore, patients with severe renal dysfunction may experience a prolonged and highly variable half-life of the drug, which the test cannot fully account for. Additionally, the use of gel-barrier tubes can result in incorrect measurement due to absorption, which represents another limitation of the testing process.
Methodology
Immunoassay
Biomarkers
LOINC Codes
- 88699-4
- 3982-6
- 3834-9
- 3983-4
Result Turnaround Time
1 day
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1 mL
Minimum Volume
0.3 mL
Container
Red-top tube or green-top (heparin) tube. Do not use a gel-barrier tube.
Collection Instructions
Transfer separated serum or plasma to a plastic transport tube. Oral treatment: peak: 75 minutes after dose; trough: immediately before next dose. I.V. treatment: immediately after loading dose; 2, 6, 12, and 24 hours after starting I.V. maintenance.
Storage Instructions
Refrigerate
Causes for Rejection
Gel-barrier tube; severe hemolysis; lipemia; icteric specimen
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 2 days |
| Refrigerated | 14 days |
| Frozen | 14 days |