gms | German Medical Science

Introduction: For the statutory health insurance (SHI) AOK PLUS a good co-operation with oncologists is of great importance to improve the quality of care as well as the drug safety. Therefore, a contract between AOK Plus, Kassenärztlicher Vereinigung Sachsen and German associations of physicians (BNGO e.V., NIO Sachsen e.V., BDU e.V.) exists. One part consists of the conduction of quality circles, in which the AOK Plus points out relevant risks in drug therapy. Tyrosine kinase inhibitors (TKI) especially are known for many interactions, as they are metabolized by CYP-enzymes and transported by P-Glycoproteins. Therefore, we analysed the prescriptions of a combination of TKIs and its interacting drugs per patient.

Methods: The basis for the analysis was prescription-data of Saxon AOK Plus-insurants in 2009. The analysis was conducted with the software PharmPRO, a database application for prescription analysis. Selected drugs known for their interaction with TKIs (e.g. Proton-pump-inhibitors, Ciprofloxacin, Simvastatin) were analysed by ATC-Code in search for combination with TKIs. The prescription dates were taken into analysis to assure simultaneous prescription and subsequent intake of interacting drugs.

Results: Our analysis shows that the prescription of TKIs in combination with drugs that might cause an interaction is common in practice. The combination of potential interacting drugs was made by the same as well as by different physicians.

Discussion and conclusion: As it is a retrospective study based on prescription data, it is not proven (but likely) that the combination of the prescribed drugs was taken simultaneously. It is unknown if the drug-dose was adjusted when a combination was given and if the combination caused a clinical relevant interaction. Moreover we did neither analyse the OTC-drugs, nor the diet, that is also known to interact with drugs. However, the evaluation points out a possible risk of interactions for TKIs with other drugs in practice. Neither increased side effects of TKI’s (in case of combining with CYP3A4-Inhibitors) nor wasting money due to lack of efficacy (in case of combining with CYP3A4-Inducers) are tolerable in this therapeutic area. We suggest that more information about relevant drug interactions should be given to all physicians prescribing for the same patient. In the same way, there is still a need for an increased co-operation with physicians, pharmacists and the SHI.