Products
Lamotrigine is commercially available as tablets and dispersible or chewable tablets (Lamictal, generics). It has been approved in many countries since 1994. Vanillin is typically added to the tablets as a flavoring agent and saccharin as a sweetener.
Structure and properties
Lamotrigine (C9H7Cl2N5, Mr = 256.1 g/mol) is a chlorinated phenyltriazine derivative that was originally developed as a folic acid antagonist and is also effective as a weak dihydrofolate reductase inhibitor. It exists as a white powder that is very sparingly soluble in water. Because of structural similarities to phencyclidine (PCP, “angel dust”), a drug test may yield false positive results.
Effects
Lamotrigine (ATC N03AX09) has antiepileptic (anticonvulsant) and mood-stabilizing properties. The effects are primarily attributed to the blockade of voltage-gated sodium channels in neurons. This stabilizes the neuronal membrane and inhibits the release of excitatory neurotransmitters such as glutamate and aspartate from the presynapse. The result is reduced excitation of the central nervous system and a reduced risk of seizures. In addition, other pharmacological actions are involved in the effects, for example, binding to voltage-gated calcium channels (see pregabalin). Lamotrigine has a long half-life between 24 and 35 hours.
Indications
- For the treatment of epilepsy.
- For the prevention of depressive episodes in patients with bipolar disorder.
Dosage
According to the professional information. The tablets are administered once or twice daily and independently of meals. Depending on the dosage form, they can usually be swallowed, suspended in water, chewed, or divided. Treatment is started gradually and the dose is adjusted individually. Discontinuation should be gradual.
Contraindications
- Hypersensitivity
- Severe renal insufficiency
Full precautions can be found in the drug label.
Interactions
Lamotrigine is conjugated by UDP-glucuronosyltransferases (glucuronidation). Corresponding and other drug-drug interactions are possible. In contrast, the drug does not interact with CYP450. Caution: hormonal contraceptives decrease plasma concentrations of lamotrigine. Appropriate concomitant use guidelines must be considered.
Adverse Effects
The most common possible adverse effects include visual disturbances (double vision, blurred vision), a skin rash, fatigue, dizziness, headache, gait disturbances, drowsiness, nausea, and diarrhea. Lamotrigine may, in rare cases, cause severe skin reactions such as Stevens-Johnson syndrome and toxic epidermal necrolysis. Therefore, if a skin rash develops, patients should contact their prescribed physician.