engleski

The effects of lamotrigine versus paroxetine on platelet biochemical markers in patients with bipolar disorders in a depressive episode

The role of serotonin (5-hydroxytryptamine, 5-HT) system in the etiology of bipolar disorders (BD) is not clear, although drugs affecting 5-HT system are used as an add-on treatment of bipolar disorder. Lamotrigine is an epileptic, a mood stabilizer, with an efficacy in bipolar depression, while paroxetine is selective serotonin reuptake inhibitor. Preclinical data suggest that lamotrigine inhibits 5-HT reuptake into platelets and neurons, and inhibits the activity of monoamine oxidase (MAO) in vitro. Aim of the study was to elucidate the effects of lamotrigine on platelet biochemical markers in vivo. In an open, comparative study, we determined spectrofluorimetrically platelet 5-HT concentration and platelet MAO activity in patients with BD in a depressive episode and in major depressed patients (Structured Clinical Interview for DSM-IV), before and after 6 weeks of treatment with lamotrigine (25-100 mg/day), or paroxetine (20 mg/day). The results showed that both drugs significantly decreased depressive symptoms and platelet 5-HT concentration, but the effects of paroxetine was significantly stronger than the effect of lamotrigine. Both drugs decreased platelet 5-HT concentration when compared to values before treatment, and to values in healthy subjects. Lamotrigine treatment significantly reduced platelet MAO activity compared to values before treatment. Paroxetine treatment did not affect platelet MAO activity. These preliminary findings suggest that short term treatment with lamotrigine affected significantly platelet biochemical markers in bipolar patients, suggesting that its beneficial antidepressant action is presumably achieved by the effects mediated by the 5-HT system.

serotonin; bipolar disorders; depression; lamotrigine; paroxetine

DOI: 10.1111/j.1399-5618.2007.00569.x