[Serum concentration of anticonvulsants. Practical guidelines for measuring and useful interpretation. Therapy Committee of the German Section of the International Epilepsy League].

The clinical relevance of being informed on the serum concentration of antiepileptic drugs has been judged very differently during the last decades. Therefore the Commission on the treatment of epilepsy (German section of the International League against Epilepsy) had the task to outline the importance of therapeutic monitoring of anticonvulsant serum concentrations. The possibility of determining the serum concentration of anticonvulsants induced the elaboration of "therapeutic drug level ranges". The usefulness of determining serum concentrations of antiepileptic drugs in clinical management of patients with epilepsy depends decisively on the following questions: Can the efficacy of antiepileptic drug treatment be increased by serum concentration monitoring? Can the rate of adverse effects of antiepileptic drugs be reduced by serum concentration monitoring? Clinical experience suggests numerous indications of therapeutic drug monitoring, scientific studies however, supporting these empirical guidelines are not available. Therefore, therapeutic drug monitoring may be restricted for some special situations which have to be justified in every single case. Tailored determinations with specific purposes are e.g.: resistance to therapy, including suspected irregular intake; suspected intoxication, particularly during combined therapy; the possibility of significant changes in the dosage-serum concentration relationship (interactions with other drugs, unusual pharmacokinetics in childhood, in pregnancy etc.).