Efficacy of Memantine as an adjuvant therapy in bipolar disorder; a double blind, randomized, clinical trial

Despite the use of different drugs in the treatment of bipolar disorder, about 50 percent of the patients are not completely cured. To strengthen the treatment effect, various medications including new antiepileptic drugs and serotonin-dopamine antagonists have been studied. Considering the potential role of NMDA receptor antagonists on the mood changes, this study was conducted to investigate the effects of memantine on acute mania as an adjunctive therapy to lithium and risperidone.
Material and Our study was a double-blind randomized clinical trial which included 40 patients with bipolar disorder in the acute phase of mania. Patients in both groups were treated with the same drug regimen (including risperidone and lithium). In the intervention group, an oral dose of memantine, 5 mg/day was started and increased to 20 mg / day after 96 hours. Patients in the control group received placebo. Severity of the symptoms before starting treatment and at the 1st, 2nd, 4th and 6th weeks after treatment was measured based on the Young Mania Rating Scale. We estimated clinical side effects of memantine by using a clinical check list.
At the end of the study, severity of manic symptoms decreased in both groups, but speed and rate of reduction of the symptoms of mania were not significantly different in the memantine group compared with the placebo group (p=0.784). The most common side effects in both groups included; restlessness (p=1.000), tremor (p=0.501), and dizziness (p=0.605), which were not significantly different in both groups.
Considering the limitations such as small sample size and short period of the study, addition of memantine 20 mg /day to the treatment regimen of the patients with bipolar disorder in the manic phase, for six weeks, had no effect on the rate and extent of symptoms of mania.