Pioglitazone adjunctive therapy for depressive episode of bipolar disorder: a randomized, double-blind, placebo-controlled trial


Background: The antidepressive effect of pioglitazone has been noted in patients with major depressive disorder in absence of metabolic syndrome. This study was conducted to evaluate the safety and efficacy of pioglitazone in patients with bipolar depression without concomitant metabolic syndrome or diabetes.

Method: Forty-eight outpatients with the diagnosis of bipolar I disorder and a major depressive episode participated in a parallel, randomized, double-blind, placebo-controlled trial, and 44 patients underwent 6-week treatment with either pioglitazone (30 mg/day) or placebo as an adjunctive treatment to lithium. Therapeutic serum lithium levels of 0.6-0.8 mEq/L were required for two or more consecutive weeks immediately before starting pioglitazone and during the 6-week study. Patients were evaluated using Hamilton Depression Rating Scale (HDRS) and Young Mania Rating Scale (YMRS) at baseline and weeks 1, 2, 4, and 6. The primary outcome was to evaluate the efficacy of pioglitazone in improving the depressive symptoms.

Result: General linear model repeated measures showed significant effect for time × treatment interaction on the HDRS scores [F(2.78, 116.65) = 4.77, P = .005]. Significantly greater reduction was observed in HDRS scores in the pioglitazone group than the placebo group from baseline HDRS score at weeks 2, 4, and 6, P = .003, .006, and .006, respectively. No serious adverse event was observed.

Conclusion: This study showed that pioglitazone could be a tolerable and effective adjunctive therapy for improving depressive symptoms in bipolar disorder without type 2 diabetes or metabolic syndrome.

Keywords: PPAR-gamma; bipolar disorder; depression; pioglitazone; randomized controlled trial; thiazolidinedione.