Lamotrigine is an anti-convulsant used in the treatment of a broad range of seizures and in conditions such as bipolar disorder. Lamotrigine is rapidly absorbed from the gastrointestinal tract and undergoes extensive metabolism. Steady state plasma concentrations are usually achieved at around five days however lamotrigine exhibits autoinduction within the first two weeks of commencing therapy which may prolong time to steady state. The metabolism of lamotrigine is affected by the use of concomitant enzyme inducers (e.g. carbamazepine, phenytoin) and inhibitors (e.g. sodium valproate) altering its half-life in adults from a mean of 24 to 35 hours to between a mean of approximately 14 and approximately 70 hours respectively. Plasma concentrations appear to overlap between responders and non-responders and between those patients experiencing or not experiencing side effects. Toxicity occurs more frequently where plasma concentrations exceed 15 mg/L.
Tube
04 (EP) – EDTA Plasma
ID
Tests&Tubes0208
Additional Information
Clinical indication for requesting lamotrigine measurement: therapeutic drug monitoring, assessing compliance.
Turn around
Turnaround time stated by Cardiff: 7 days
Send to
Blood Sciences LGI
(Test referred to: Cardiff toxicology lab)
Contact
For further details please contact Leeds Pathology customer services: l[email protected].
Advice
Full information on all referred tests can be found on the referred tests information database, EQMS reference BSF2REC17003.
Collection Con
Trough sample required.
Instructions to lab: centrifuge sample, separate and freeze plasma.
Minimum volume: 1mL plasma.
Sample REQ
Blood
Ref. Range Notes
Therapeutic range: 3-15 mg/L
Units
mg/L