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22973 Procainamide and NAPA (PA)

Procainamide and NAPA (PA)
Test Code: PROCSO
Synonyms/Keywords
NAPA (N-Acetyl Procainamide), Pronestyl (Procainamide), N-Acetyl Procainamide
Useful For
Monitoring therapy with procainamide, assessing compliance, evaluating procainamide toxicity
Specimen Requirements
Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)
Serum​ ​Serum Separator Tube (SST) ​Red Top Tube (RTT) ​0.5 mL ​0.25 mL
Collection Processing Instructions
​Serum separator tubes should be centrifuged within 2 hours of collection.  Red top tubes should be centrifuged and aliquoted within 2 hours of collection.
Specimen Stability Information
Specimen Type Temperature Time
​Serum ​ ​ ​Refrigerated ​7 days
​Ambient ​24 hours
​Frozen (preferred) ​14 days
Rejection Criteria
​Gross Hemolysis
Performing Laboratory Information
Performing Location Day(s) Test Performed Report Available
Methodology/Instrumentation
​Mayo Clinic Laboratories Monday through Saturday​ 1-2 days
Homogeneous Enzyme Immunoassay
Reference Lab
Test Information

Procainamide (PA) is indicated in the treatment of life-threatening ventricular arrhythmias.

PA is metabolized to an active metabolite, N-acetylprocainamide (NAPA), with metabolism controlled by genetically determined enzymes. In patients with normal renal function, fast metabolizers will have a PA:NAPA ratio less than 1 at 3 hours after the dose is administered. Slow acetylators (PA:NAPA ratio >2 after 3 hours) are more likely to present with systemic lupus erythematosus-like symptoms and may test positive for antinuclear antibodies.

Patients who have prolonged exposure to procainamide levels above 12 mcg/mL or a NAPA concentration of 40.0 mcg/mL or higher are very likely to exhibit symptoms of toxicity, which are characterized by hypotension, ventricular fibrillation, widened QRS complex, junctional tachycardia, oliguria, confusion, nausea, and vomiting.

Renal disease, hepatic disease, cardiac failure, and states of low cardiac output reduce the metabolism and clearance of PA and NAPA.

Coadministration of histamine H2 receptor antagonists, such as cimetidine and ranitidine reduce renal clearance of PA and NAPA resulting in higher plasma concentrations of each.

Reference Range Information
PROCAINAMIDE
Therapeutic concentration: 4.0-10.0 mcg/mL
Critical value: >12.0 mcg/mL
 
N-ACETYLPROCAINAMIDE
Therapeutic concentration: 12.0-18.0 mcg/mL
Critical value: > or =40.0 mcg/mL
Interpretation
​Administration of a dose of 50 mg/kg will usually yield the optimal trough concentration in the range of 4.0 to 10.0 mcg/mL for procainamide and 12.0 to 18.0 mcg/mL for N-acetylprocainamide. 
Outreach CPTs
CPT Modifier
(if needed)
Quantity Description Comments
​80192 ​1
Synonyms/Keywords
NAPA (N-Acetyl Procainamide), Pronestyl (Procainamide), N-Acetyl Procainamide
Ordering Applications
Ordering Application Description
​COM
​Procainamide and NAPA (PA)
​Cerner ​Procainamide and NAPA (PA)​
If the ordering application you are looking for is not listed, contact your local laboratory for assistance.
Specimen Requirements
Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)
Pediatric Minimum Volume
(no repeat)
Serum​ ​Serum Separator Tube (SST) ​Red Top Tube (RTT) ​0.5 mL ​0.25 mL
Collection Processing
​Serum separator tubes should be centrifuged within 2 hours of collection.  Red top tubes should be centrifuged and aliquoted within 2 hours of collection.
Specimen Stability Information
Specimen Type Temperature Time
​Serum ​ ​ ​Refrigerated ​7 days
​Ambient ​24 hours
​Frozen (preferred) ​14 days
Rejection Criteria
​Gross Hemolysis
Useful For
Monitoring therapy with procainamide, assessing compliance, evaluating procainamide toxicity
Reference Range Information
PROCAINAMIDE
Therapeutic concentration: 4.0-10.0 mcg/mL
Critical value: >12.0 mcg/mL
 
N-ACETYLPROCAINAMIDE
Therapeutic concentration: 12.0-18.0 mcg/mL
Critical value: > or =40.0 mcg/mL
Interpretation
​Administration of a dose of 50 mg/kg will usually yield the optimal trough concentration in the range of 4.0 to 10.0 mcg/mL for procainamide and 12.0 to 18.0 mcg/mL for N-acetylprocainamide. 
For more information visit:
Performing Laboratory Information
Performing Location Day(s) Test Performed Report Available
Methodology/Instrumentation
​Mayo Clinic Laboratories Monday through Saturday​ 1-2 days
Homogeneous Enzyme Immunoassay
Reference Lab
For billing questions, see Contacts
Outreach CPTs
CPT Modifier
(if needed)
Quantity Description Comments
​80192 ​1
For most current information refer to the Marshfield Laboratory online reference manual.