Evaluation of efficacy and the pharmacokinetic interactions between valproic acid and lamotrigine as a combination theraphy in bipolar disorder treatment.

The aims of the study are: (1) to investigate the pharmacokinetic interactions between valproic acid and lamotrigine drugs that are used as a new generation antiepileptics used in the treatment of bipolar disorder, (2) to examine the possible relationships between plasma concentrations of valproic acid/lamotrigine and the incidence of clinical response/adverse effects.In this study 12 bipolar disorder patients have been studied. Plasma concentrations of lamotrigine were measured by HPLC and plasma concentrations of valproic acid were measured by FPIA technology in patients. Clinical response to lamotrigine and valproic acid were determined by MADRS, BECH- Rafaelson, CGI and IGD; adverse effects were determined by UKU side effect scale.After adding lamotrigine in bipolar disorder patients who are treated with valproic acid, there was no statistically significant difference between the plasma valproic acid concentrations in 0-14, 0-28 and 14-28.days. There was no statistically significant difference in plasma valproic acid concentrations between the patients who did and did not use quetiapine in addition to combination treatment.Our findings showed that there is no statistically significant difference among the patients responding and non-responding to drug theraphy and patients in which adverse reactions were and were not observed with respect to plasma drug concentrations.We think that valproic acid and lamotrigine combination is effective and safe in the treatment of bipolar disorder.Key words: Bipolar disorder, lamotrigine, valproic acid.