Synonyms: LAMICTAL
Clinical significance
Lamotrigine is a broad-spectrum anticonvulsant that is well tolerated. It appears to work by blocking voltage-dependent sodium channels. It is well absorbed from the gut and is metabolised in the liver by glucuronidation. Side effects and toxic effects include ataxia, double vision, dizziness, weakness, nausea and vomiting. It can cause skin reactions, which may be severe.
Clinical indications
Monitoring of treatment.
Sample type
The patient must have a blood sample taken.
Preparation
You must fast for at least 8 hours; a small amount of water is allowed. You must have been standing or sitting upright for at least 30 minutes. For periodic monitoring of the blood concentration of the medicine, so that results can be compared over time, the blood sample should always be taken the same number of hours after taking the medicine.
Notes
Valproate increases its blood concentration; phenytoin, phenobarbital and carbamazepine can reduce it.
Monitoring blood levels is indicated especially when the dose is being adjusted and when the medicine is used together with other anticonvulsants.
When taken by mouth, bowel disturbances (diarrhoea) can reduce absorption of the medicine and therefore its blood concentration.