LAMOTRIGINE TOXICITY SECONDARY TO SERTRALINE

Blood level monitoring helps to determine the therapeutic and toxic ra nges for anticonvulsants and antidepressants. We investigated initial drug-drug interactions between lamotrigine and sertraline. We report o n case histories of two epileptic patients who were initially on lamot rigine and to whom sertraline was added to control psychiatric feature s. In case 1, a total daily dose of 25 mg sertraline, with nondetectab le sertraline and desmethylsertraline blood levels, resulted in a doub ling of the lamotrigine blood level with symptoms of toxicity. In case 2, a 25 mg reduction in the total daily dose of sertraline resulted i n halving of the lamotrigine blood level even though the lamotrigine d osage was increased by 33%. This shows that sertraline has potent inte ractions with lamotrigine metabolism. The authors hypothesize that inh ibition of glucuronidation is responsible. Clinicians are advised to o bserve for symptoms of toxicity and to do serial blood levels to monit or this interaction.