Background: Tiagabine (Gabitril) is a GABA uptake inhibitor recently introduced in the United States as an adjunctive treatment for partial complex seizures. Three published studies have addressed the use of tiagabine for bipolar disorder (BPD); two described positive results and one negative results. We assessed the efficacy of add-on tiagabine in a larger sample of adult BPD outpatients.
Methods: Twenty-two adult outpatients with DSM-IV diagnosed BPD of some type who were considered unsatisfactory responders to standard medications for BPD were treated in an open fashion with adjunctive tiagabine in a low-dose range. After baseline demographic data and mood state at the time of entry were documented, each patient was monitored clinically for at least 6 months while the dose of tiagabine was adjusted according to the patient's clinical status. The subjects were rated using the clinical global impression-bipolar version scale (CGI-BP).
Results: After 6 months, eight (36%) of the patients were responders to tiagabine by CGI-BP rating. The dose range of tiagabine for responders was 1-8 mg per day. All 14 nonresponders had to discontinue tiagabine because of unacceptable but reversible side effects; one nonresponder experienced breakthrough absence seizures.
Limitations: This study was performed in a nonrandom, open naturalistic clinical setting. The sample size was small.
Conclusions: Low-dose tiagabine appears to have mood-stabilizing and antimanic properties as an add-on medication for some adult outpatients who have BPD refractory to standard medications. Tiagabine appears to be safe for most adult BPD outpatients. The results of this preliminary open study await confirmation by double-blind controlled studies.