Clinical use: Clinicians use the test for Primidone to assess compliance for the drug and to monitor appropriate therapeutic level, and assess toxicity.
Background: Primidone is used for control of grand mal seizures that are refractory to other antiepileptics and seizures of psychomotor or focal origin.Primidone exhibits a volume of distribution of 0.6 L/kg and a half-life of 8 hours.

Primidone is an anticonvulsant of the pyrimidinedione[4] class, the active metabolites of which, phenobarbital (major) and phenylethylmalonamide (PEMA) (minor), are also anticonvulsants. It is used mainly to treat complex partial, simple partials, generalized tonic-clonic seizures, myoclonic, akinetic seizures. Primidone has been occasionally used to treat long QT syndrome, cerebral palsy, and athetosis.

Primidone works via interactions with voltage-gated sodium channels which inhibit high-frequency repetitive firing of action potentials. It is much less toxic in overdose than phenobarbital. Along with carbamazepine, phenobarbital, and phenytoin, primidone is an inducer of metabolic enzymes in the liver, which means that it accelerates the metabolism of many other pharmaceuticals. Like other anticonvulsants, primidone has been associated with hyperhomocysteinemia, folate deficiency and its various symptoms (birth defects, depression, and megaloblastic anemia), reduced calcium absorption, and various bone diseases. It also shares with most other anticonvulsants the tendency to cause sedation.

Reference ranges: 5-10ng/L
Associated diseases:
Patient Preparation: None required
Specimen requirements: Serum (SST) sample
Turnaround time: 1 week
Additional information:
Referred test: Referred test
Location: Therapeutic Drug Monitoring Unit