PGx and/or TDM? How could they interact in daily practice?

Functional differences for the metabolising enzymes can have a direct influence on the pharmacokinetics of the psychotropic drugs and thus affect the plasma levels.

Under the standard dose, it is possible that a slow metabolic rate may result in overdosing effects with the corresponding tolerability problems or pharmacokinetically induced loss of effect if the metabolic rate is too high.

An additional complication arises from the fact that psychotropic drugs act as a mixture of parent substance and various metabolites. If individual components have their own spectrum of effects and side-effects, patient-specific differences regarding metabolism may lead to different tolerability and efficacy/effectiveness outcomes related to themedication.

These metabolic differences can be related to interactions with other drugs, food, smoking, etc., or can be pharmacogenetically determined as "innate interactions" in patients (phenoconversion).

Pharmacogenetic differences in treatment with psychotropic drugs can now be assessed and therefore drug therapy be better adapted in individual patients. Dose guidelines from international specialist groups are available for this purpose.

Therapeutic drug monitoring allows level deviations potentially underlying unsatisfactory treatment outcomes to be directly detected.

Since the effects of pharmacogenetic variants and other interactions have an essential impact on drug metabolism, assessing for pharmacogenetic abnormalities is just as useful as the assessment of other interactions and patient adherence.

Publication History

Article published online:
12 March 2024