Background
Imatinib, a tyrosine kinase inhibitor (TKI), is a substrate and inhibitor of cytochrome P450, therefore imatinib can be affected by concomitant drugs or a change in the concentration of other drugs. The absorption of imatinib can also be modified due to interactions. Haouala et al. (2011) reviewed available evidence about it.
Purpose
To investigate the incidence of, and potential interactions between, imatinib and other drugs the patients were on.
Materials and methods
This cross-sectional study was done in June 2013. Patients diagnosed with chronic myeloid leukaemia (CML) and treated with imatinib were selected. A database of drug interactions was made. The information was obtained from Micromedex and Lexicomp databases and from several scientific papers. Patients’ other medicines were obtained from the digital treatment histories. Interactions were analysed according to the drug, effects on concentrations, mechanism and severity.
Results
41 patients were selected, 56% female. The median age was 59 years (range: 24–91). A total of 73 potential interactions were detected in 33 patients: median of 1.8 interactions per patient (0–7). 45% of the interactions affected the concentration of imatinib: 77% of them could increase its concentration and 23% decrease it. 70% of the interactions affected the metabolism of the TKI and 30% modified its absorption. 55% of the interactions could change the concentration of the other drug (88% in terms of increasing it and 12% decreasing it). Interacting drugs were omeprazole (13%), simvastatin (10%) and ibuprofen (8%). Regarding the severity, 95% were classified as ‘moderate’, 5% as ‘mild’ and none as ‘major’.
Conclusions
We found a high incidence of potential interactions between imatinib and other medicines. Almost half of the interactions affected imatinib. These findings led us to establish regular communication with physicians to avoid possible adverse effects or lack of efficacy.
No conflict of interest.
Background
Tyrosine kinase inhibitors (TKIs) have revolutionised the treatment of Chronic Myeloid Leukaemia (CML). Adherence to this chronic treatment is essential to attain the therapeutic objectives expected.
Purpose
To identify patients on TKIs with adherence problems.
Materials and methods
Patients diagnosed with CML and treated with a TKI were selected. Adherence was determined by the Simplified Medication Adherence Questionnaire (SMAQ), a Visual Analogue Scale (VAS) and the medicines dispensing records. Patients were considered non-adherent (NA) if they had a response indicating non adherence in the SMAQ, a score below 9 on the VAS or fewer than 90% of the days with enough medicines at home.
Results
48 patients were selected: 50% male and a median age of 59 years (range: 24–91). 40 patients were treated with imatinib, 6 with nilotinib and 2 with dasatinib. According to SMAQ, 12 patients were NA, 31 adherent (A) and 5 did not answer (n/a). According to VAS, 2 patients were NA, 42 A and 4 n/a. Dispensing records revealed 6 patients NA and 42 A. The combination of these three methods identified 16 patients as NA (33%) and 32 as A (67%). Looking at the TKI prescribed, the percentage of NA was 28% of patients with imatinib, 50% of patients with nilotinib and 100% of those with dasatinib.
Conclusions
We found that a high percentage of patients (33%) were non-adherent. It is important to identify these patients in order to strength pharmaceutical care. This can be essential for their successful treatment.
No conflict of interest.
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