5PSQ-056 Safety between the use of commercial and generic imatinib: is the excipient relevant?

Background Imatinib (IM) is a tirosin kinase inhibitor approved to treat chronic myeloid leukaemia (CML) and other diseases. This drug can be administrated in commercial and generic formulations. Not all generic formulations are exactly designed as the commercial drug because the excipient is not always the same. In our hospital, we changed imatinib from commercial to generic in June 2016. Purpose The aim of our study was to analyse if there were significant differences in terms of safety between the use of commercial and generic formulations of imatinib from June 2016 to September 2018 in our hospital, and to compare tolerance changes when the excipient was changed. Material and methods We performed a retrospective, observational and descriptive study to evaluate patients treated with commercial imatinib (CI) and generic imatinib (GI) in a second-level hospital. With this purpose we analysed the next variables: demographic data, diagnosis, changes between commercial and generic treatment, adverse events (AEs) with both presentations and dose. Results We included 24 CML patients (58.3% males); average age 67.5±9.13 years. Of all the patients who were on treatment with IM, 66.7% switched from CI to GI, 25% started with GI, 4.16% did not switch and remained with CI and 4.16% changed to nilotinib. Of the 22 patients treated with GI, 45.5% stopped therapy and restarted CI and 4.5% changed to bosutinib because of serious AEs. In 63.6% of the patients treated with GI, significant AEs were found in 50% (haematological, cutaneous, gastrointestinal, ocular, muscular, systemic, respiratory side effects). Patients treated with CI experienced AE in 81% (>Grade III–IV in 5.9%). Significant differences between both presentations were found with the excipients: GI contained hydroxypropylmethylcellulose and CI had microcrystalline cellulose. Conclusion Patients treated with GI experienced more serious AEs than with CI. This difference could be explained because of the difference in excipients between both presentations. In conclusion, we think that inclusion of new generic drugs in hospital guidelines should include a comparison of excipients’ profile before their admission, in order to evaluate tolerance. References and/or acknowledgements Haematology department. No conflict of interest.