Long-term safety of tiagabine

Tiagabine (TGB) is now registered in > 20 countries and the total number of treated patients approaches 90,000. Short-term safety data were derived ma inly from five placebo-controlled, add-on studies in adults with therapy-re sistant partial epilepsy, and two conversion to TGB monotherapy studies. Ce ntral nervous system (CNS)-related adverse effects, most frequently dizzine ss, were common with TGB treatment during the titration period; the risk be came similar to placebo rates during fixed-dose periods. Other adverse even ts that were more frequent in TGB- than in placebo-treated patients were as thenia, nervousness, tremor, concentration difficulties, depressive mood, a nd language problems. TGB doses should be titrated slowly and taken with fo od to avoid rapid increases in plasma concentrations, thus minimizing the r isks of adverse events. Overall, >2,500 patients have been exposed to TGB d uring clinical trials, with 1,274 patients treated > 12 months, the majorit y of whom received TGB 24-60 mg/day. No idiosyncratic reactions have been l inked to the use of TGB, and no abnormalities in hematology or common chemi stry values were reported. In all the epilepsy studies combined, 21% of pat ients discontinued treatment because of adverse events, usually during the first 6 months of treatment. No adverse effects on cognitive abilities were detected when the neuropsychological effects of TGB add-on therapy and mon otherapy were evaluated. TGB does not appear to cause an excess risk of psy chosis or increase the incidence of status epilepticus or spike/wave discha rges. No evidence of a relationship between visual field constriction and T GB treatment was found in a study of 15 patients converted to TGB monothera py (mean dose, 22 mg/day; mean duration, 2.5 years) who had a full ophthalm ologic evaluation. In conclusion, the characteristics of TGB in the managem ent of partial epilepsy are enhanced by its favorable side-effect profile i n the cognitive area.