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.