An open trial of pregabalin as an acute and maintenance adjunctive treatment for outpatients with treatment resistant bipolar disorder

Background: Pregabalin is a structural analog of GABA, similar to gabapentin. It does not have a FDA indication for any psychiatric disorder in the USA. There has been one case report of the successful use of pregabalin as an augmenting agent in a patient with Bipolar Disorder (BD). In the present open label study, not subsidized by the manufacturer, the investigators prospectively evaluated the acute and maintenance efficacy of pregabalin as an adjunctive medication for a group of treatment refractory outpatients with BD. Methods: Older adolescent and adult outpatients with any type of DSM-IV diagnosed BD, who were considered treatment nonresponders to multiple standard medications for BD, were treated with adjunctive pregabalin. The baseline mood state before initiation of pregabalin was compared to the mood state after an acute trial of pregabalin using the Clinical Global Impression-Bipolar Version Scale (CGI-BP). All acute responders were treated for a minimum of two months. Follow-up maintenance treatment data was obtained for the acute pregabalin responders for three years after the 18 month acute phase of the study. Results: Fifty-eight total patients were treated adjunctively with pregabalin. Twenty-four (41%) were rated as acute responders. For the acute responders, pregabalin produced either a mood stabilizing effect, antidepressant effect or antimanic effect. Intolerable side-effects were the most common reason (79%) for a failed acute trial of pregabalin. None of the side effects resulted in serious medical complications. No patient abused pregabalin, and there were no adverse drug-drug interactions despite an average of 3.3 concurrent other psychiatric medications. The maintenance data revealed that 10 (42%) of the original 24 acute pregabalin responders were still taking pregabalin as an add-on medicine for an average of 45.2 months (range 42-48, SD: 2.35). Limitations: This study has an open label observation design. Conclusions: The results of this preliminary open study suggest that pregabalin is a safe and effective acute and maintenance adjunctive treatment for a significant number of treatment-resistant outpatients with any type of BPD. It appears to have mood stabilizing and antidepressant properties in addition to antimanic effects. Similar studies using a double-blind, randomly controlled design would be useful to confirm the reliability and validity of the results of this study.