Effectiveness of adjunctive therapy with tiagabine in mentally disabled patients with epilepsy.

Previous reports justified positive impact of tiagabine, a new-generation antiepileptic drug on neuropsychological functioning as well as minimal risk of psychiatric exacerbations. In this prospective, open, observational, non-comparative, short-term--6 months' study we evaluated efficacy and tolerability of tiagabine as add-on in polytherapy in 30 young adults with both refractory epilepsy and mild or moderate mental retardation. About 40% of patients experienced improvement in seizure frequency of 50% or more and none complained of seizure deterioration. Overall seizure frequency fell down from a mean 9.9 at the baseline to 6.3 seizure days per month. The seizure rate was reduced from 14.9 to 9.2 per month after 24 weeks of add-on phase. Adjunctive tiagabine therapy appeared to be associated with reduction in overall seizure severity characteristics expressed as enhancement of mild seizures from 30 to 50% of patients and reduction in severe seizures from 30 to 16%. Responders reported an improvement in most health-related quality of life domains but mostly cognition, medication effects and social functioning. The majority (90%) of patients did not report additional adverse effects with tiagabine; the most common complains associated with central nervous system (vertigo, weakness, nervousness) were transient and did not cause discontinuation. Blood counts and liver functional tests did not show any clinically relevant changes. In this short-term observation tiagabine seemed to be a beneficial antiepileptic drug for mentally retarded patients with epilepsy as it decreased seizure frequency and severity, improved the patients' sense of the quality of life without enhancement of the risk of adverse effects in polytherapy.