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Epic Code LAB1230568 Procainamide and N-Acetylprocainamide, Serum

Additional Codes

Mayo Code: PA

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Useful For

Monitoring therapy with procainamide

 

Assessing compliance

 

Evaluating procainamide toxicity

Specimen Type

Serum


Specimen Required


Collection Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 0.5 mL

Collection Instructions:

1. Serum gel tubes should be centrifuged within 2 hours of collection.

2. Red-top tubes should be centrifuged and the serum aliquoted into a plastic vial within 2 hours of collection.


Laboratory Test Directory Note:

COLLECTION NOTE: Volumes listed are in serum or plasma, draw approximately 2 1/2 times the requested volume in whole blood.

Specimen Minimum Volume

0.25 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Frozen (preferred) 14 days
  Refrigerated  7 days
  Ambient  24 hours

Reject Due To

Gross hemolysis Reject

Day(s) Performed

Monday through Saturday

Reference Values

Procainamide

Therapeutic: 4.0-10.0 mcg/mL

Critical value: >12.0 mcg/mL

 

N-acetylprocainamide

Therapeutic: 12.0-18.0 mcg/mL

Critical value: ≥40.0 mcg/mL

Clinical 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.

Cautions

No significant cautionary statements

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.

Reporting Name

Procainamide and NAPA, S

Method Name

Homogeneous Enzyme Immunoassay

Method Description

These assays are based on a homogeneous enzyme immunoassay technique. The assay is a competition assay between the drug in the sample and drug labeled with the enzyme glucose-6-phosphate dehydrogenase (G6PD) for antibody binding sites. Enzyme activity decreases upon binding to the antibody, so the drug concentration in the sample can be measured in terms of enzyme activity. Active enzyme converts oxidized nicotinamide adenine dinucleotide (NAD) to NADH, resulting in an absorbance change that is measured spectrophotometrically. Endogenous serum G6PD does not interfere because the coenzyme functions only with the bacterial (Leuconostoc mesenteroides) enzyme employed in the assay.(Package inserts: Roche Procainamide and N-acetylprocainamide. Roche Diagnostics; 08/2015)

CPT Code Information

80192

LOINC Code Information

Test ID Test Order Name Order LOINC Value
PA Procainamide and NAPA, S Obsolete

 

Result ID Test Result Name Result LOINC Value
8683 Procainamide, S 3982-6
2461 N-acetylprocainamide, S 3834-9
2462 Procainamide + NAPA 3983-4

Report Available

Same day/1 to 2 days

Test Classification

This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

Clinical Reference

1. Milone MC, Shaw LM: Therapeutic drugs and their management. In: Rifai N, Horvath AR, Wittwer CT, eds. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics, Elsevier; 2018: 800-831

2. Brunton LL, Hilal-Dandan R, Knollmann BC, eds. Goodman and Gilman's: The Pharmacological Basis of Therapeutics. McGraw-Hill; 2018

Forms

If not ordering electronically, complete, print, and send a Therapeutics Test Request (T831) with the specimen.