Ordering Recommendation

Optimize drug therapy and monitor patient adherence; the active metabolite of primidone is phenobarbital.

Mnemonic

PRIM

Methodology

Immunoassay

Performed

Sun-Sat

Reported

Within 24 hours

New York DOH Approval Status

This test is New York DOH approved.

Specimen Required

Patient Preparation
Collect

Plain red. Also acceptable: Green (sodium heparin).

Specimen Preparation

Allow specimen to clot completely at room temperature. Separate serum from cells within 2 hours of collection. Transfer 1 mL serum or plasma to an ARUP Standard Transport Tube. (Min: 0.8 mL)

Storage/Transport Temperature

Refrigerated.

Unacceptable Conditions

Separator tubes.

Remarks
Stability

After separation from cells: Ambient: 1 week; Refrigerated: 1 week; Frozen: 1 month

Reference Interval

Test Number
Components
Reference Interval
  Phenobarbital
Age
Reference Interval (µg/mL)
0-2 months 15.0-30.0
3 months and older 15.0-40.0

  Primidone (Mysoline) 5.0-12 µg/mL

Interpretive Data

Primidone concentrations greater than 15 µg/mL in conjunction with therapeutic levels of phenobarbital may be associated with toxicity.


Component Age Interpretive Data (µg/mL)
Phenobarbital 0-2 months Toxic: 40.1 or greater
Phenobarbital 3 months and older Toxic: 50.1 or greater

Compliance Category

FDA

Note

Hotline History

N/A

CPT Codes

80188; 80184

Components

Component Test Code* Component Chart Name LOINC
0090230 Phenobarbital 3948-7
0090240 Primidone (Mysoline) 3978-4
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.

Aliases

  • Luminal
  • Mysoline
  • Mysoline Primidon)
  • Phenobarbital
  • Primidone
Primidone and Metabolite