Test ID: PBPR
Primidone and Phenobarbital, Serum
Secondary ID 
A test code used for billing and in test definitions created prior to November 2011
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Useful For Suggests clinical disorders or settings where the test may be helpful
Assessing compliance
Monitoring for appropriate therapeutic level
Assessing toxicity
Method Name A short description of the method used to perform the test
Immunoassay
Includes phenobarbital determination.
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Aliases Lists additional common names for a test, as an aid in searching
Luminal (Phenobarbital)
Mysoline (Primidone)
Phenobarbital
Primidone (Mysoline)
Primidone w/Phenobarb Metabolite, Serum
Solfoton (Phenobarbital)
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Container/Tube: Red top
Specimen Volume: 1 mL
Additional Information: Phenobarbital (metabolite) determination is required for proper interpretation.
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | Mild OK; Gross reject |
| Lipemia | Mild OK; Gross reject |
| Icterus | Mild OK; Gross reject |
| Other | NA |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum Red | Refrigerated (preferred) | 14 days |
| Ambient | 14 days | |
| Frozen | 14 days |
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
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 t.i.d. 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.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
PRIMIDONE
Therapeutic concentration
Children (<5 years): 7.0-10.0 mcg/mL
Adults: 9.0-12.5 mcg/mL
Toxic concentration: > or =15.0 mcg/mL
PHENOBARBITAL
Therapeutic concentration
Infants and children: 15.0-30.0 mcg/mL
Adults: 20.0-40.0 mcg/mL
Toxic concentration: > or =60.0 mcg/mL
Interpretation Provides information to assist in interpretation of the test results
At steady-state, which is achieved approximately 2 weeks after therapy is initiated, blood levels of primidone that correlate with optimal response to the drug range from 9.0 to 12.5 mcg/mL for adults and 7.0 to 10.0 mcg/mL for children <5 years of age.
The corresponding levels for phenobarbital are 20 to 40 mcg/mL for adults and 15 to 30 mcg/mL for children <5 years of age.
Dosage adjustment based on blood level information is the best way to obtain optimal response to the drug.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
At the same time that the primidone level is monitored, one should also monitor the phenobarbital level, as phenobarbital is a metabolite of primidone.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
Rall TW, Schleifer LS: Drugs effective in the therapy of the epilepsies: primidone. In Goodman and Gilman's The Pharmacological Basis of Therapeutics. 8th edition. Edited by AG Gilman, TW Rall, AS Nies, P Taylor. New York, Pergamon Press, 1990, pp 446-447
Method Description Describes how the test is performed and provides a method-specific reference
Primidone is measured by the enzyme-multiplied immunoassay technique. (Palmer SM, Kaufman RA, Salamone SJ, et al: Cobas Integra: clinical laboratory instrument with continuous and random-access capabilities. Clin Chem 1995;41:1751-1760)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Sunday; Varies
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
80184-Phenobarbital
80188-Primidone
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
| Result ID | Reporting Name | LOINC Code |
|---|---|---|
| 31153 | Primidone, S | 3978-4 |
| 31154 | Phenobarbital, S | 3948-7 |
External
link
PDF
document
Excel
document
Word
document