Objective: The purpose of this study is that determine whether or not the efficacy of lamotrigine, which is an anticonvulsant with a stabilizer quality in neuronal membranes and has inhibitor activity in sodium and calcium channels and presynaptic neurons, is related to blood levels in bipolar disorder. We compared the period before and after lamotrigine use in bipolar cases and studied if there was any relationship between lamotrigine blood levels and clinical progress.
Method: Forty cases, diagnosed with bipolar disorder type I according to the DSM-IV, and taking lamotrigine for at least two years together with any mood stabilizer (lithium, anticonvulsants or atypical antipsychotics), were evaluated consecutively. For evaluation, being in remission period was set as a criterion for these cases. Patient interviews were carried out with the SCID-I in bipolar cases. Before or after protective treatment, the SCIP-TURK Mood Disorders Diagnosis and Patient Registration Form were filled in by the patients and their relatives. Later blood samples were taken from the bipolar cases in order to analyze lamotrigine blood levels.
Results: In the bipolar cases, when comparing before and after long term maintenance of lamotrigine, it was determined that after using lamotrigine, total episode and depressive episode frequency decreased, episode severity was less (p< 0.001, 0.039, and 0.04, respectively) and the fast onset and termination ratio decreased (p= 0.027). When evaluated according to these variables, in long term maintenance, the ratio of good treatment response to lamotrigine among bipolar cases was 77.5%. In cases with good treatment response to lamotrigine, while lamotrigine doses were found to be similar to the others (135.5±52.7/155.6±69.7 mg/day), lamotrigine blood levels were found to be higher (3.8±1.9/2.0±1.1 µg /ml) (p= 0.005). No correlation was shown between lamotrigine dose and lamotrigine blood levels (r= 0.185, p= 0.254).
Conclusion: As a result, lamotrigine is an efficient choice in long term maintenance treatment of bipolar disorder. The relationship of this efficacy to lamotrigine blood levels must be explored in future studies.