What are drugs doing in our body?

Determination of the drug level

Determination of drug levels, also known as therapeutic drug monitoring (TDM), is an important part of modern drug therapy. We measure the concentration of drugs in the blood or in blood compartments such as blood serum or plasma.

These studies are important because of the widely varying individual pharmacokinetics. The term pharmacokinetics describes the uptake, transport, distribution and breakdown of drugs in the body - fundamental things for the effectiveness of an administered drug. In addition to the body's own individual characteristics, some of which are hereditary, environmental factors such as diet, smoking, other drugs administered at the same time, etc. determine how high the concentration of the drugs in the blood is.

This examination is also very important for patients who have to take drugs that have a narrow therapeutic range or whose overdose could lead to severe symptoms of intoxication. This also applies to drugs that can easily be over- or underdosed, or those whose blood concentration is influenced by other drugs. In the case of reduced kidney or liver function due to diseases, the drugs with TDM can be adjusted more safely.

The aim of the examination is to dose the prescribed medication individually so that they are in the so-called reference range. This means that they are dosed high enough to achieve the desired effect and at the same time dosed low enough to avoid undesirable side effects.

These investigations are carried out with liquid chromatography and subsequent mass spectrometry. This method is highly specific for the drug under investigation and its breakdown products and provides very precise results.

The results are technically and medically validated and advice is available on the areas of action and drug interaction.

For the assessment of the brain penetration of drugs, see Molecular Biological Diagnostics and for further drug safety, see Clinical Chemistry.