Since TKI are metabolized with cytochrome P450 system which is a common pathway for drug-drug interactions. However, these interactions might be overlooked by clinicians. The aim of this study is to evaluate the drug-drug interactions in patients receiving TKI.
Between May 2007 and March 2015, the data of 265 patients receiving TKI for any reason were evaluated retrospectively. All prescribed medications (PMs) received during TKI therapy for 6 months period were noted and drug-drug interactions with TKI were evaluated. Additionally the nature of interaction was described as ‘increase or decrease in TKI level or cautious use of TKI recommended’. The interaction between TKI and PMs was checked from Up-To-Date web site or ''medscape.com/drug-interaction checker''.
In the study, 265 patients who are taking TKI were noted. 251 patients (94.8%) have been taking PMs additional to TKI. The median age was 56 year (17-87), most common diagnosis was gastrointestinal stromal tumor (27.5%) followed by kidney tumor (26.3%). Most common TKI has been used was Imatinib (21.9%) and Lapatinib (21.9%). The most common PM groups during 6 months period was non-steroidal anti inflammatory and acetaminophen (50.2%), proton pomp inhibitors (41.4%), antibiotics (33.1%), cardiovascular system drugs (33.5%) and narcotic analgesics (21.1%). The interaction rate between TKI and PMs was 54.2%. The nature of interaction was; decrease in TKI level in 39.7% of patients and increase in TKI level in 30.1% of patients. 77.1% of patients have been warned as cautious use of TKI due to increase risk of side effect. The side effect was emphasized as QT prolongation.
TKI drug interaction is usually overlooked by clinicians. Our study revealed that more than 90% of patients who are taking TKI are also prescribed another medication. There is a drug-drug interaction between TKI and prescribed medications in more than half of these patients. TKI-prescribed drug interaction has been caused decrease effectiveness of treatment and increase the rate of side effects and medical cost. The TKI –drug interaction risk might be decreased by increasing the knowledge of the physicians from other specialties about recent molecular treatments.
Clinical trial identification
Legal entity responsible for the study
Ankara Numune Education and Research Hospital
All authors have declared no conflicts of interest.