Zin en onzin van bloedspiegelbepalingen: Therapeutic drug monitoring bij ouderen

The goal of therapeutic drug monitoring (TDM) is to maximise the effect of drug therapy and to minimise toxicity. TDM is meaningful if on the one hand there is a relationship between the serum concentration of the drug and its effect and on the other hand there is no obvious relationship between dose and efficacy due to wide interindividual variability in pharmacokinetics. In case of digoxin, phenytoin, carbamazepine and valproic acid interindividual pharmacokinetics can vary to such an extent, that drug therapy should be guided by determination of serum drug levels.