Lamotrigine plus quetiapine combination therapy in treatment-resistant bipolar depression

Lamotrigine and quetiapine are commonly used in bipolar disorder, but there are no published systematic studies of their use in combination for treatment-resistant bipolar depression.

We studied 39 trials in outpatients (15 with bipolar I disorder, 22 with bipolar II disorder, and 1 with bipolar disorder not otherwise specified; 1 patient had 2 trials) with depression resistant to quetiapine or lamotrigine who were taking a mean of 1.7 other prescription psychotropic medications. Patients were given either open-label lamotrigine or quetiapine naturalistically, for up to 12 weeks of combination therapy.

Lamotrigine (mean dose, 204.2 mg/d) plus quetiapine (mean dose, 188.5 mg/d) increased the euthymia rate (0.0% to 46.2%), decreased syndromal (79.5% to 30.8%) and subsyndromal (20.5% to 15.4%) depression rates, and improved Clinical Global Impression-Severity (mean change, -1.0) and Global Assessment of Functioning (mean change, +5.9) scores. Approximately one-fifth of patients discontinued therapy (20.5%) or required subsequent additional pharmacotherapy (20.5%). Only 10.3% discontinued due to adverse effects, and there was no significant change in mean body weight.

The findings of this uncontrolled open pilot study must be viewed with caution. However, randomized, double-blind, placebo-controlled studies are warranted to confirm the possibility that combination therapy with lamotrigine and quetiapine is effective and well tolerated in patients with treatment-resistant bipolar depression.