Clinicians use the test for lamotrigine for monitoring serum concentration of lamotrigine, and for testing compliance. Serum concentration can be used to adjust lamotrigine doses in patients receiving other anticonvulsant drugs which interact pharmacokinetically with lamotrigine.
Levetiracetam is used treatment of partial, myoclonic, and tonic-clonic seizures, and can be used for manic states and migraine prophylaxis. Levetiracetam has very favourable pharmacokinetics with good bioavailability and rapid achievement of steady state. Its hepatic metabolism is minimal and non-oxidative, making it safe for use with hepatic enzyme inducers or inhibitors. The major metabolite is a carboxylic acid derivate, which is inactive and accounts for roughly one quarter of the administered dose. Levetiracetam is excreted renally, with a mean half-life of 7 hours in adults and slightly less than that in children.
Renal dysfunction may warrant therapeutic monitoring and/or dose adjustment. Given the lack of drug interactions and favourably pharmacokinetics, the primary uses for therapeutic drug monitoring of levetiracetam are compliance assurance and management of physiological changes such as puberty, pregnancy and aging.
Toxicities associated with levetiracetam use include decreased hematocrit and red blood cell count, decreased neutrophil count, somnolence, asthenia and dizziness. These toxicities may be associated with blood concentrations in the therapeutic range.
45 – 118 µmol/L
Serum, SST. Spin & separate serum, alternatively send the primary sample tube via first class post.
Therapeutic Drug Monitoring Unit