1 Introduction
Clinical pharmacology could be defined as a translational discipline between basic
pharmacology and applied pharmacology and how they are used in drug discovery
and development and in solving practical therapeutic problems in individuals and
populations.^1 One of the basic principles of clinical pharmacology and pharmaco-
therapy in general could be synthetized in the phrase “the right drug for the right
patient.” This phrase aligns with thebroader definitionof personalized medicine,
e.g., tailoring of medical treatment to the individual characteristics of each patient.^2
This individual patient’s characteristics include interindividual variability in drug
response as a consequence of multiple factors, such as gender, age, and/or concom-
itant illness and medication, genomics, epigenomics, and the environment.^3
This chapter therefore includes three different areas of clinical pharmacology that
are important in the individualization of the therapy such as therapeutic drug mon-
itoring, individualization in patients with renal and liver dysfunction, and
pharmacogenetics/pharmacogenomics. In the broader definition of personalized med-
icine, we have to take into account the specifics of drug therapy in the elderly,
pregnancy, lactation, and children as special populations, but it would exceed the
extent of this chapter.
2 Therapeutic Drug Monitoring
Therapeutic drug monitoring (TDM) is a branch of clinical chemistry and clinical
pharmacology that specializes in the measurement of medication concentrations in
blood.^4 To ensure that best practice in TDM is achieved, accurate and clinically
meaningful drug concentrations can only be obtained by close collaboration
between the prescribing physician, the laboratory specialist, the clinical pharma-
cologist, and the patient. TDM has been often identified with a simple drug
measuring.However, it is only one part of TDM that provides expert clinical
interpretation, as well as the concentration to ensure full clinical benefit. Its main
focus is on drugs with a narrow therapeutic range, i.e., drugs that can easily be
under- or overdosed. TDM can be based ona prioripharmacogenetic, demo-
graphic, and clinical information and/or on thea posteriorimeasurement of blood
concentrations of drugs (pharmacokinetic monitoring) or biological surrogate or
end-point markers of effect (pharmacodynamic monitoring).^5
There are numerous variables that influence the interpretation of drug concen-
tration data: time, route and dose of drug given, time of blood sampling, handling
(^1) Aronson ( 2010 ).
(^2) Bates ( 2010 ).
(^3) Schwab and Schaeffeler ( 2012 ).
(^4) Marshall and Bangert ( 2008 ).
(^5) IATDMCT Executive Committee ( 2011 ).
266 D. Vitezic ́et al.