The use of primidone in the treatment of refractory bipolar disorder

Four anticonvulsant medications (carbamazepine, valproate, gabapentin and lamotrigine) have received attention in the psychiatric literature as efficacious treatment for bipolar disorder, either as monotherapy or as adjunctive agents. Although two earlier reports in 1993 suggested that primidone may also be helpful for bipolar disorder, this older anticonvulsant has not been evaluated in any subsequent studies to confirm these earlier findings. In the present prospective open study, 26 patients with refractory bipolar disorder were treated with primidone as an adjunctive therapy. Eight (31%) patients experienced a persistent positive therapeutic effect. Five (19%) patients were considered partial or temporary responders to primidone. The remaining 13 patients (50%) were considered treatment failures. Although a 31% response rate is considered modest in most psychotropic medication studies, the authors believe that this success rate is significant in this refractory patient population and should provide impetus for future more scientific studies to confirm the preliminary findings of this open trial.