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HelpTEST ID PRMB Primidone and Phenobarbital, Serum
Reporting Name
Primidone and Phenobarbital, SSpecimen Type
SerumSpecimen Required
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.
Specimen Minimum Volume
0.25 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum | Refrigerated (preferred) | 7 days |
| Frozen | 28 days | |
| Ambient | 72 hours |
Testing Algorithm
Includes phenobarbital determination.
Method Name
PRIMD: Immunoassay
PBR: Kinetic Interaction of Microparticles in a Solution (KIMS)
Reject Due To
| Gross hemolysis | Reject |
Reference Values
Primidone
Therapeutic: 5.0-12.0 mcg/mL
Critical value: ≥15.0 mcg/mL
Phenobarbital
Therapeutic: 10.0-40.0 mcg/mL
Critical value: ≥60.0 mcg/mL
Day(s) Performed
Monday through Sunday
Report Available
Same day/1 daySpecimen Retention Time
1 weekPerforming Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
PRIMD-80188
PBR-80184
Forms
If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:
-Neurology Specialty Testing Client Test Request (T732)
-Therapeutics Test Request (T831)
Useful For
Assessing compliance
Monitoring for appropriate therapeutic levels of primidone and phenobarbital
Assessing toxicity
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| PRIMD | Primidone, S | No | Yes |
| PBR | Phenobarbital, S | Yes | Yes |
Clinical Information
Primidone is used for control of grand mal seizures that are refractory to other antiepileptics and seizures of psychomotor or focal origin.
Primidone is initially dosed in progressively increasing amounts starting with 100 mg at bedtime to 250 mg 3 times a day after 10 days of therapy in adults.
Primidone exhibits a volume of distribution of 0.6 L/kg and a half-life of 8 hours.
When monitoring primidone and phenobarbital levels simultaneously, the specimen should be drawn just before the next dose is administered.
Primidone is not highly protein bound, approximately 10%. Phenobarbital is a metabolite of primidone. Like phenobarbital, there are no known major drug-drug interactions that affect the pharmacology of primidone. Toxicity associated with primidone is primarily due to the accumulation of phenobarbital. Diagnosis and treatment are as described for PBAR / Phenobarbital, Serum.