ABSTRACT
The terms “serum concentration” and “plasma concentration” are often used interchangeably in therapeutic drug monitoring (TDM). In recent years some research works have studied the correlation between “serum” and “plasma” concentration when monitoring some particular drugs and the influence of the collection tube on concentration. We decided to study vancomycin, due to its wide use in our hospital and the increasing interest of some physicians in the clinical importance of monitoring this drug. The purposes of this chapter are the following: to determine whether there are differences between serum and plasma concentration of vancomycin; to propose a regression formula in order to predict serum concentrations when measuring plasma levels of vancomycin; and to establish the influence of freezing plasma and serum samples on the results. From a statistical standpoint, serum and plasma vancomycin samples cannot be used interchangeably. Therefore it is necessary to establish whether serum or plasma samples are to be used in both routine and research work.
