Lamotrigine

Lamotrigine (Lamictal) is one of the new anti-epileptic drugs approved inÿAustralia for add-on therapy in severe partial epilepsy. It has been available in the UK and several European countries for the past few years.

What are its applications?

Since its introduction, Lamotrigine has proved most effective when used in conjunction with other anti-epileptic drugs to treat adults with previously uncontrollable partial seizures (complex and simple), which may also include secondary generalised tonic-clonic seizures.

Of those participating in clinical trials in Britain and Europe, approximately one third experienced a marked improvement in the frequency and severity of their seizures while taking Lamotrigine in addition to existing medication.

Lamotrigine has also shown good results in preliminary studies involving its use as a single drug therapy. Of 69 participants in a 1992 study, for example, 50 maintained good seizure control after stopping other medications.

Others who may benefit from the use of this drug include people with Lennox-Gastaut syndrome (LGS). Indications in Australia now include partial generalised epilepsy in adults and in children in cases refractory to other therapy.

Benefits for people with epilepsy

Lamotrigine is readily absorbed and metabolised within one to three hours of ingestion, without being affected by the presence of food. It has little apparent influence on the effectiveness of other anti-epileptic drugs being taken concurrently. Other medications, including oral contraceptives, appear to be unaffected by the presence of Lamotrigine. Indeed, unlike several other anti-epileptic drugs, Lamotrigine can be taken in conjunction with the pill without risking contraceptive failure.

Clinical studies have shown fewer effects on psychomotor function than other comparable anti-epileptic drugs and Lamotrigine does not appear to impair cognitive function. For people experiencing unmanageable partial seizures, Lamotrigine offers improved seizure control with reductions in both the frequency and severity of seizures.

In Australia several thousand patients have been studied and the results conform to the overseas pattern of results. It seems that the benefits exceed side effects very significantly.

In patients taking more than one drug, if Lamotrigine is found to be more effective, then the other drugs can be withdrawn.

In the presence of sodium valproate (Epilim) Lamotrigine is generally given in smaller doses. The two drugs may interact and control some seizures better than either drug alone.

Possible side effects

In overseas studies, the development of a severe skin rash was the most common reason for people discontinuing Lamotrigine. This side effect occurred in 2.3 per cent of those participating in a 1992 U.K. study with one per cent discontinuing the drug. From preliminary evidence of further tests, however, it appears that slowly introducing Lamotrigine, with gradual increases in dosage until the required dose has been reached, may assist in preventing the rash. The rash may be very severe and may be associated with fever and other signs of illness. It is relatively rare but appears to be more common in children. Very slow introduction of the drug is recommended.

Slow introduction means using the smallest tablet size and using only 12.5-25mgm for 2 weeks before a slow increase up to 200mgm - 400mgm per day. This slow method of introduction and gradual increase has resulted in a marked drop in the incidence of skin rashes. This is important because the rash may occasionally cause severe complications involving the mucus membranes such as mouth, throat eyes etc.

Other reported side effects are those commonly experienced with many of the current range of anti-epileptic drugs and include dizziness, blurred vision, impaired coordination, headache, nausea and drowsiness. Lamotrigine, however, appears to cause fewer side effects than other comparable medications, and may have a favourable effect on alertness.