Liquid chromatography tandem mass spectrometry for therapeutic drug monitoring of immunosuppressive drugs: Achievements, lessons and open issues

Currently therapeutic drug monitoring (TDM) of immunosuppressive drugs is one of the best established fields of application of TDM as a tool dedicated to therapy guidance and patient care improvement. LC-MS/MS techniques were introduced to this field about 20 years ago, and enabled a huge progress towards providing more adequate overall quality and turnaround time for TDM services. However, numerous LC-MS/MS difficulties have also been recognized and approaches to deal with them have been developed. Moreover, some further issues must be resolved to realize the full potential of this technique. This article aims to provide an update of the LC-MS/MS literature with a focus on new developments and applications that have been reported during the last five years. In addition, it summarizes important lessons and defines current needs in the context of TDM services, which must be addressed in the near future.