Clinical Relevance of TDM of SSRIs

Automated Interlaboratory Comparison of Therapeutic Drug Monitoring Data and Its Use for Evaluation of Published Therapeutic Reference Ranges

Therapeutic drug monitoring is a tool for optimising the pharmacological treatment of diseases where the therapeutic effect is difficult to measure or monitor. Therapeutic reference ranges and dose-effect relation are the main requirements for this drug titration tool. Defining and updating therapeutic reference ranges are difficult, and there is no standardised method for the calculation and clinical qualification of these. The study presents a basic model for validating and selecting routine laboratory data. The programmed algorithm was applied on data sets of antidepressants and antipsychotics from three public hospitals in Denmark. Therapeutic analytical ranges were compared with the published therapeutic reference ranges by the Arbeitsgemeinschaft für Neuropsychopharmakologie und Pharmakopsychiatrie (AGNP) and in additional literature. For most of the drugs, the calculated therapeutic analytical ranges showed good concordance between the laboratories and to published therapeutic reference ranges. The exceptions were flupentixol, haloperidol, paroxetine, perphenazine, and venlafaxine + o-desmethyl-venlafaxine (total plasma concentration), where the range was considerably higher for the laboratory data, while the calculated range of desipramine, sertraline, ziprasidone, and zuclopenthixol was considerably lower. In most cases, we identified additional literature supporting our data, highlighting the need of a critical re-examination of current therapeutic reference ranges in Denmark. An automated approach can aid in the evaluation of current and future therapeutic reference ranges by providing additional information based on big data from multiple laboratories.

Pharmacogenomics and adverse drug reactions in diagnostic and clinical practice

Pharmacogenetics and pharmacogenomics deal with genetically determined variations in how individuals respond to drugs. They hold the potential to revolutionize drug therapy. The clinical need for novel approaches to improve pharmacotherapy stems from the high rate of adverse reactions to drugs and their lack of effectiveness in many individuals. Despite the accumulation of research findings showing the potential for clinical benefit for several drug-metabolizing enzymes and some receptors that constitute drug targets, the translation of these findings into tangible clinical applications occurs very slowly. The main steps for clinical implementation of pharmacogenomics include: a) education of clinicians and all other parties involved in the use and benefits of pharmacogenomics; b) execution of large prospective clinical and pharmacoeconomic studies showing the benefit of pharmacogenomic genotyping; c) provision of incentives to develop tests; d) development of specific clinical guidelines; and e) creation of a solid regulatory and ethical framework. Furthermore, the potential should be explored to use existing therapeutic drug monitoring laboratories to introduce pharmacogenomic testing into hospitals. Overall, our thesis is that pharmacogenomics is already a reality in clinical practice and is bound to continue gaining acceptance by clinicians in the coming years.

Clin Chem Lab Med 2007;45:801–14.