The novel antiepileptic drugs that include lamotrigine, gabapentin and topiramate have expanded the pharmacotherapeutic options for the treatment of bipolar disorder. These drugs have successfully been used as mood stabilizers. Their improved pharmacokinetic and tolerability profiles contribute to improved safety, efficacy and compliance.

Dr. Hussain presented a clinically based, single center, open-label study that was conducted to evaluate the long-term safety and efficacy of topiramate. Topiramate was used as adjunctive therapy for 135 patients with bipolar I (62 patients) or bipolar II (73 patients) disorder. The duration of treatment was 36 months. The patient population consisted of 46 males and 89 females with a mean age of 34 years. The mean age of onset of bipolar disorder was 21 years. The mean duration of the current episode was 11 weeks. All participants were previously treated with mood stabilizers and antidepressants but failed to respond adequately. This study rated all participants on the Hamilton Depression Rating Scale; all participants were clinically depressed. Participants were followed for 1, 2, 3, 6, 12, 18, 24, 30 and 36 months. Topiramate was administered at an initial dose of 25 mg/hs, rising every two days to 200 mg/hs, and later up to a maximum of 600 mg/day.

The results show that topiramate was well-tolerated. Clinically significant responses were observed within two to four weeks of treatment. A decrease in the use of concomitant medications with topiramate adjunctive therapy was reported over the 36 months of treatment. Patients using topiramate used less antidepressants, benzodiazepines and mood stabilizers. The use of novel antipsychotics was not affected by topiramate.

Regarding the side effect of body weight, topiramate resulted in a decrease in body weight of all participants. This weight loss averaged 8 to 9 kg for each participant. The data provide evidence that topiramate is an effective mood stabilizer. Dr. Hussain noted that the reduced need for concomitant medications suggests the possibility of decreased side effects and increased efficacy with the use of a fewer medications. Dr. Hussain concluded that topiramate has a beneficial use as a mood stabilizer with antidepressant properties for the treatment of bipolar disorder.

(abstract Session 14 No. 41)