2 - 5 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Serum or plasma
0.3 mL (Note: This volume does not allow for repeat testing.)
Red-top tube, lavender-top (EDTA) tube, or green-top (heparin) tube. Do not use a gel-barrier tube. The use of gel-barrier tubes is not recommended due to slow absorption of the drug by the gel. Depending on the specimen volume and storage time, the decrease in drug level due to absorption may be clinically significant.
Transfer separated serum or plasma to a plastic transport tube.
Maintain specimen at room temperature.
Gel-barrier tube; whole blood samples; unspun samples that are not separated from cells
Therapeutic: trough: 2.0−20.0 μg/mL
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 that 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 predominantly to an inactive 2-N-glucuronide conjugate. Peak plasma concentration occurs at 1.4 to 4.8 hours following oral administration.1 The elimination half-life varies from 12 to 70 hours. The longer half-lives are observed in patients on concomitant valproic acid therapy. Accordingly, if lamotrigine is coadministered with 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 include dizziness, diplopia, ataxia, blurred vision, nausea and vomiting, somnolence, headache, and rash. The anticonvulsants phenytoin, phenobarbital, primidone, and carbamazepine can reduce lamotrigine levels when coadministered.2 Conversely, lamotrigine can reduce levels of levetiracetam when coadministered.3 In children, investigators4 have found large differences in lamotrigine plasma levels in patients with improvement in seizure frequency, but patients who were seizure-free had higher lamotrigine levels than other patients in the study.
|Order Code||Order Code Name||Order Loinc||Result Code||Result Code Name||UofM||Result LOINC|
|716944||Lamotrigine (Lamictal), Serum||6948-4||716945||Lamotrigine, Serum||ug/mL||6948-4|
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