Procainamide and N-Acetylprocainamide, Serum
Use
The test is useful for monitoring therapy with procainamide, assessing patient compliance, and evaluating procainamide toxicity. Procainamide is used in the treatment of life-threatening ventricular arrhythmias and is metabolized to N-acetylprocainamide (NAPA). The metabolism is affected by genetic variations in enzymes, and understanding the PA:NAPA ratio is critical, especially in detecting lupus-like symptoms in slow acetylators. Monitoring for procainamide levels above 12.0 mcg/mL and NAPA concentrations of 40.0 mcg/mL or higher is crucial as these levels may lead to toxicity, evidenced by symptoms like hypotension and ventricular fibrillation.
Special Instructions
If not ordering electronically, the following forms should be completed and sent with the specimen: Cardiovascular Test Request (T724) or Therapeutics Test Request (T831).
Limitations
The test has not been cleared or approved by the US Food and Drug Administration and has been modified from the manufacturer's instructions. Prolonged exposure to high levels of procainamide and NAPA can lead to various toxicological effects, particularly in individuals with kidney, liver, or cardiac dysfunction that impair drug clearance.
New York Approved
Methodology
Immunoassay (Homogeneous Enzyme Immunoassay)
Biomarkers
LOINC Codes
- 3983-4
- 3982-6
- 3834-9
- 3983-4
Result Turnaround Time
1-2 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
0.5 mL
Minimum Volume
0.25 mL
Container
Plastic vial
Collection Instructions
Serum gel tubes should be centrifuged within 2 hours of collection; red-top tubes should be centrifuged and serum aliquoted into a plastic vial within 2 hours of collection.
Causes for Rejection
Gross hemolysis
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 24 hours |
| Refrigerated | 7 days |
| Frozen | 14 days |