The quantification and pharmacological interpretation of drug concentrations in blood (serum or plasma) is widely known as therapeutic drug monitoring (TDM). In clinical practice, TDM is an established precision tool that provides the fundamental prerequisites for personalized treatment. Specifically, in neurology and psychiatry, TDM can be used as part of the process of prescription of medications in specific patient subgroups, including children and adolescents, pregnant women, elderly patients, patients with intellectual disabilities, patients with substance abuse
disorders, individuals with pharmacokinetic idiosyncrasies and forensic patients. Clinicians may consider TDM in the case of lack of clinical response to therapeutic doses of medication, assessment of drug adherence, tolerability and drug-drug interactions. This is the Greek translation of a short summary of the updated consensus guidelines compiled by the TDM task force of the Arbeitsgemeinschaft für Neuropsychopharmakologie und Pharmakopsychiatrie
(AGNP). It includes therapeutic reference ranges, laboratory alert levels, recommendation levels for prescribing TDM for dosage optimization without specific indications, conversion factors, factors for calculation of dosage-related drug concentrations and metabolite-to-parent ratios.