Abstracts

Rationale: Lamotrigine (LTG) was finally approved by the Japan Ministry of Health, Labor and Welfare (JMHLW) in December 2008 as add-on treatment with older anti-epileptic drugs (AEDs) far behind the times when LTG established its status of AEDs in Europe and USA. Therefore drug lag is still one of the serious issues in our medical society. We have four newer AEDs at present in Japan, namely, gabapentin, topiramate, levetiracetam, and LTG. Although the paradigm shift from older AEDs to newer AEDs has progressed in some parts of our country, older AEDs still ensure its strong share in the market. There is no report up to the present with a large volume of Japanese patients regarding experience of add-on treatment by LTG. Then we investigated effectiveness of LTG, especially seizure reduction, the number of preceding AEDs, the continuation rate, and adverse reactions.Methods: Patients treated by LTG from 2008 when the drug came onto the market in Japan through the end of 2012 were reviewed retrospectively using medical charts.Results: Two hundred ninety-four patients with epilepsy were treated by LTG at our institute. Children treated at the pediatric section of the epilepsy center were excluded from this study. The average number of preceding AEDs was 1.42. Classification of epilepsy revealed 174 cases (59%) of symptomatic localization-related epilepsy, 70 cases (24%) of idiopathic generalized epilepsy, and 19 cases (6%) of symptomatic generalized epilepsy. Thirty-one cases were identified as miscellaneous or unclassified. Ninety-nine patients with localization-related epilepsy were followed up in our epilepsy center, and demonstrated 48% of them got seizure freedom by LTG. Patients with more than 50% seizure reduction were 20%. Forty-six cases with generalized epilepsy showed higher rate of seizure freedom (67%). The continuation rate was 78%. Sixty-six cases dropped out of LTG treatment. Reasons of withdrawal were insufficiency for seizure reduction or worsening in frequency (26 cases), skin rash (14 cases), agitation and irritability (2 cases), sleepiness (3 cases), and miscellaneous (21 cases). The occurrence of skin rash was 4.8% among the total of cases. The first add-on to the preceding AEDs was carried out in 41%. The doses of LTG when seizure freedom was accomplished distributed mainly below 200mg daily.Conclusions: Since LTG needs strict slow titration to prevent skin rash, and JMHLW still keeps add-on treatment as other newer AEDs, it is not easy to see effectiveness for seizure reduction by LTG, However, this study demonstrated satisfactory results in terms of its seizure reduction and high continuation rate. Treatment of the first add-on by LTG especially showed excellent consequences. Therefore LTG will keep its major role in the treatment of epilepsy in Japan as well.