Lamotrigine as Adjunct to Paroxetine in Acute Depression: A Placebo-Controlled, Double-Blind Study

Background: Mood stabilizers appear to be more potent in treating mania than depression. The anticonvulsant lamotrigine has been shown to be effective for bipolar depression. This study examines putative antidepressive properties of lamotrigine in a mainly unipolar routine clinical patient population.

Method: Forty patients with a depressive episode (DSM-IV criteria) requiring psychiatric intervention received lamotrigine or placebo using a fixed dose escalation scheme with a target dose of 200 mg/day for 9 weeks. Additionally, all patients were treated with paroxetine. Hamilton Rating Scale for Depression (HAM-D) and Clinical Global Impressions scale (CGI) ratings were used to monitor therapeutic efficacy.

Results: Adjunctive treatment with lamotrigine did not result in a significant difference in HAM-D total score at the endpoint of the study when compared with paroxetine alone. However, lamotrigine demonstrated significant efficacy on core depressive symptoms as reflected by HAM-D items 1 (depressed mood; p=.0019), 2 (guilt feelings; p=.0011), and 7 (work and interest; p=.049) and the CGI-Severity of Illness scale (p<.0001). Patients receiving lamotrigine had fewer days on treatment with benzodiazepines and fewer withdrawals for treatment failure. Lamotrigine appeared to accelerate the onset of action of the antidepressant. Two patients on lamotrigine treatment developed neutropenia, and 1 developed a benign rash. There was no detectable pharmacokinetic interaction between lamotrigine and paroxetine.

Conclusion: Lamotrigine might have antidepressive properties in unipolar patients and may accelerate onset of action when given in combination with typical antidepressants.