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 Field Name  Data Description
Test Name  Lamotrigine (Lamictal), Serum
Code  Lamotrigine Level., Lamictal.
CPT Code  80175
Last Modified  
Test Name  Lamotrigin.
Patient Preparation  
Spec. Requirements  Blood
Tube  Red, Drk Green, or Lavender(EDTA) Top
Collection Volume  4.0 mL Red, 2.0 mL Lavender, or 4.0 Drk Green Top
Storage  Ambient, Refrigerate, or Freeze 14 days
Routine TAT  
Days Test Performed  
Performed by BHS  None
See Availability  
Reference Lab  LabCorp of America
Reference Lab Code  716944 Lamotrigine (Lamictal), Serum
Clinical Use  Lamotrigine is an antiepileptic drug (AED) of the phenyltriazine class that is chemically unrelated to existing AEDs. The precise mechanism of action is unknown although it has been postulated lamotrigine inhibits voltage-sensitive sodium channels thereby stabilizing neuronal membranes and consequently modulating presynaptic transmitter release of excitatory amino acids (eg, glutamate, aspartate). Lamotrigine is 55% bound to plasma proteins and is metabolized predominately to an inactive 2-N-glucuronide conjugate. Peak plasma concentration occurs at 1.4-4.8 hours following oral administration.[1] The elimination half-life varies from 12 to 70 hours. The longerhalf-lives are observed in patients on concomitant valproic acid therapy. Accordingly, if lamotrigine is co-administeredwith valproic acid, the dose of lamotrigine must be reduced to less than half the normal dosage. The most common adverse reactions are associated with the use of lamotrigine in combination with other anticonvulsants, and includes dizziness, diplopia, ataxia, blurred vision, nausea and vomiting, somnolence, headache, and rash. The anticonvulsants phenytoin, phenobarbital, primidone, andcarbamazepine can reduce lamotrigine levels when co- administered.[2] Conversely, lamotrigine can reduce levels of levetiracetam when co-administered.[3] In children, investigators[4] have found large differences in lamotrigineplasma levels in patients with improvement in seizure frequency, but patients who were seizure-free had higher lamotrigine levels than other patients in the study.
Reference Range  
Critical Value  
Testing Sample Type  Serum or Plasma
Min Lab Testing Volume  0.5 mL
Special Handling  
Lab Notes  
Methodology  LC/MS-MS - Liquid Chromatography/Tandem Mass Spectrometry
Limitations  Causes for Rejection: Gel-barrier tube

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