BMA Concise Guide to Medicine & Drugs

Lamotrigine

Brand name Lamictal

Used in the following combined preparations None

QUICK REFERENCE

Drug group Anticonvulsant drug

Overdose danger rating Medium

Dependence rating Low

Prescription needed Yes

Available as generic Yes

GENERAL INFORMATION

Lamotrigine, introduced in 1993, is an anticonvulsant drug that is prescribed, either alone or in combination with other anticonvulsants, for the treatment of epilepsy. The drug acts by restoring the balance between excitatory and inhibitory neurotransmitters in the brain. Lamotrigine may be less sedating than older anticonvulsants, and there is no need for blood tests to determine the level of the drug in the blood.

Lamotrigine may cause a number of minor adverse effects, most of which will respond to an adjustment in dosage. Lamotrigine is also occasionally used in specialist centres to treat bipolar affective disorder (manic depression).

INFORMATION FOR USERS

Your drug prescription is tailored for you. Do not alter dosage without checking with your doctor.

How taken/used Tablets, chewable tablets, dispersible tablets.

Frequency and timing of doses 1–2 x daily.

Adult dosage range 100–500mg daily (maintenance) (100–200mg with sodium valproate). Smaller doses are used at start of treatment. Dose may vary if other anticonvulsant drugs are being taken.

Onset of effect Approximately 5 days at a constant dose.

Duration of action Up to 24 hours.

Diet advice None.

Storage Keep in original container at room temperature out of the reach of children.

Missed dose Take as soon as you remember. If your next dose is due within 2 hours, take a single dose now and skip the next.

Stopping the drug Do not stop taking the drug without consulting your doctor, who will supervise a gradual reduction in dosage. Abrupt cessation increases the risk of rebound seizures.

Exceeding the dose An occasional unintentional extra dose is unlikely to be a cause for concern. Large overdoses may cause sedation, double vision, loss of muscular coordination, nausea, and vomiting. Contact your doctor immediately.

POSSIBLE ADVERSE EFFECTS

Serious adverse effects are rare with lamotrigine. the most common side effects are headache, tiredness, nausea, insomnia, blurred or double vision, and poor muscle coordination; discuss with your doctor if headache or tiredness are severe or if any of these other symptoms occur. A rash is also a common adverse effect and may indicate a serious hypersensitivity reaction, especially when accompanied by mouth ulcers; if you develop a rash, call your doctor immediately. More rarely, lamotrigine may cause flu-like symptoms, sore throat, unusual bruising, or facial swelling; call your doctor at once if any of these symptoms occur.

INTERACTIONS

Sodium valproate increases and prolongs the effectiveness of lamotrigine. A reduced dose of lamotrigine will be used.

Antidepressants, antipsychotics, rifampicin, mefloquine, and chloroquine may counteract the anticonvulsant effect of lamotrigine.

Carbamazepine may reduce lamotrigine blood levels, but lamotrigine may increase the side effects of carbamazepine.

Phenytoin and phenobarbital may decrease blood levels of lamotrigine so a higher dose of lamotrigine may be needed.

SPECIAL PRECAUTIONS

Be sure to tell your doctor if:

· You have long-term liver or kidney problems.

· You have any blood disorder.

· You are taking other medicines.

Pregnancy Safety in pregnancy not established. Discuss with your doctor.

Breast-feeding The drug passes into the breast milk and may affect the baby. Discuss with your doctor.

Infants and children Not recommended under 2 years. Not recommended as a single therapy under 12 years. Doses may be relatively higher than adult doses due to increased metabolism.

Over 60 No special problems.

Driving and hazardous work Your underlying condition, in addition to the possibility of sedation, dizziness, and vision disturbances while taking lamotrigine, may make such activities inadvisable. Discuss with your doctor.

Alcohol Alcohol may increase the adverse effects of this drug.

PROLONGED USE

No special problems.