Lamotrigine monitoring

The mainstay of therapy, a mood stabilizer, should be continued at the same dose that was used to achieve remission during acute phase therapy. Ongoing use of the mood stabilizer requires periodic monitoring of medication levels to ensure compliance. In addition to other laboratory evaluations such as complete blood counts, liver, kidney, and thyroid studies are needed to ensure that the mood stabilizer is being well tolerated. Lamotrigine is the only mood stabilizer that does not require periodic laboratory monitoring. 

LAMOTRIGINE 1. ANTIBIOTICS -rifampicin 2. OESTROGENS 3. PROGESTOGENS 1 lamotrigine levels t metabolism Monitor levels... 

RIFAMPICIN LAMOTRIGINE l lamotrigine levels t metabolism Monitor levels... 

The effects of overdosage of lamotrigine include sedation, ataxia, diplopia, nausea, vomiting, hypertonia, nystagmus, and prolongation of the QRS complex (SEDA-18, 66). Cardiac rhythm should be monitored. Multiple oral dosing with activated charcoal enhances lamotrigine elimination, but its value in overdose is unknown. 

Froscher W, Keller F, Kraemer G, Vogt H. Serum level monitoring in assessing lamotrigine efficacy and toxicity. Epilepsia 1999 40(Suppl 2) 252. 

Wong IC, Mawer GE, Sander JW. Adverse event monitoring in lamotrigine patients a pharmacoepidemiologic study in the United Kingdom. Epilepsia 2001 42(2) 237-44. 

George S, Wood AJ, Braithwaite, RA. Routine therapeutic monitoring of lamotrigine in epileptic patients using a simple and rapid high performance liquid chromatographic technique. Ann Chn Biochem 1995 32 584-8. 

Anticonvulsants Phenytoin, lamotrigine Therapeutic drug monitoring recommended may require anticonvulsant dose increase. 

B. Other useful laboratory studies include electrolytes, glucose, creatinine (gabapentin, topiramate), CBC (felbamate), liver transaminases, bilirubin (fel-bamate), and ECG monitoring (lamotrigine). 

Monitor asymptomatic patients for a minimum of 4-6 hours. Admit symptomatic patients for at least 24 hours after lamotrigine, felbamate, topiramate, or zonisamide ingestions. 

The authors suggest that sertraline may competitively inhibit the glu-curonidation of lamotrigine. Evidence so far appears limited to this case report. In view of the increased risk of rash with increased lamotrigine levels (see also Lamotrigine + Valproate , below), it may be prudent to monitor the combination. Further study is needed. 

Information about these interactions is limited. Nevertheless, concurrent use should be monitored. Anticipate the need to reduce the dose of phenytoin, phenobarbital or primidone if mesuximide is given. The dose of lamotrigine may need to be increased if mesuximide is given. There is also some evidence that the dose of valproate may need to be increased. 

Information is limited, but the interactions of remaeemide with carbamazepine, phenobarbital and phenytoin appear to be established, but so far only the carbamazepine interaction seems to have been shown to be of clinical importance. Even so, until more experience has been gained, monitor the effeets of eoneurrent use with phenytoin or phenobarbital. No interaction occurs between remaeemide and valproate or lamotrigine. 

The pharmacokinetic interaction would appear to be established however, since the relationship between lamotrigine levels and efficacy is not clear, the clinical relevance of the decrease is uncertain. Lamotrigine efficacy should be monitored in patients taking lopinavir/ritonavir, and probably any ritonavir-boosted regimen. Anticipate the need to increase the lamotrigine dose. 

A method for the analysis of the basic antiepileptic compounds felbamate, lamotrigine, carbamazepine, carbamazepine-10,11-epoxide, gabapentin, pregabalin, levetiracetam, and oxcarbazepine monohydroxy derivative (oxcarb MHD) in human plasma is described. This protocol incorporates a simplified sample preparation step followed by quantitative high performance chromatography-tandem mass spectrometry detection of commonly prescribed and monitored anticonvulsant drugs. Since polytherapy is common in epilepsy patients, use of a multiconstituent assay can improve laboratory efficiency and reduce required analytical time. 

Commercial immunoassays have long been available for the classic anticonvulsants such as phenytoin, carbamazepine, valproic acid, primidone, and ethosuximide and generally provide useful results under normal TDM conditions. Kits for the newer anticonvulsants such as lamotrigine, gabapentin, zonisamide, and levetiracetam have become available only recently so their effectiveness in monitoring in a broad population cannot yet be evaluated. While targeted immunoassay can be a very efficient and cost-effective way... 

A 1-ml portion of plasma was extracted twice (pH 7.4 and 12] using a 1 1 mbcture of diethyl ether and ethyl acetate after addition of methaqualone as internal standard. The extract was analyzed by GC-MS in the selective-ion monitoring (SIM) mode (m/z 185, 187, 255, 257 for lamotrigine and 235, 250 for methaqualone). A five-point calibration graph was established using spiked plasma samples [65]. The procedure was linear from 0.5 to 20 mg/L (r = 0.991) with coefficients of variation of less than 15%. The LOD was 0.1 mg/L. As we have seen, therapeutic concentrations ranged from 1 to 6 mg/L. The presented method has proved to be suitable for TDM as well as for clinical toxicology. 

---