Clinical experience using gabapentin adjunctively in patients with a history of mania or hypomania

Gabapentin is an anticonvulsant proposed to have mood-stabilizing properties. It has been effective in the add-on treatment of refractory partial seizures and secondary generalized tonic-clonic seizures. It has the advantage of a favorable side effect profile and lack of drug interactions.

Twelve consecutive outpatients with persistent, treatment-resistant bipolar spectrum disorders were treated with gabapentin in combination with other medications. Patients were started at 300 mg/day, which was titrated according to clinical response. Response was assessed every 3-4 weeks with a Clinical Global Improvement Scale. Dosage and side effects were noted. The median peak dose was 2400 mg/day.

One patient had a marked response to gabapentin; seven, a moderate response; two, mild; and two, no response to treatment. Six patients discontinued treatment due to somatic complaints (i.e., sedation or fatigue). The most frequently reported adverse effect was sedation.

Gabapentin was added openly, and rating was nonblind in this case series. The use of concomitant medications could have increased the amount of sedation experienced with gabapentin.

Overall, gabapentin was associated with moderate improvement of mood symptoms. Given the severity and chronicity of these patients' illness, a moderate response must be considered a relative success. Controlled studies of gabapentin are needed to clarify its role in the treatment of bipolar disorder.