Tigecycline versus INR increase; more than expected?

Objectives: The aim of the study was to investigate the frequency of tigecycline-associated INR abnormality.Methods: Patients who were hospitalized between June and September 2016 and treated with tigecycline including therapy were extracted from hospital database and retrospectively reviewed. INR values at the beginning and end of treatment were compared.Results: A total of 79 patients who received tigecycline were identified by analyzing the hospital database. Nineteen patients were excluded from the study since INR was not measured at the beginning and/or end of treatment. In 55 of the 60 patients, INR levels were within normal limits (0.9-1.2) at the beginning of treatment while 19 of these 55 (34,5%) had prolonged INR after treatment. Prolongation was found to be mild (1.01-1.25 x ULN-upper limit of normal) in 12 of 19 patients, moderate (1.26-1.5 x ULN) in six and severe (1.51-3.0 x ULN) in one. In 10 of 19 patients, tigecycline was stopped, and the INR values normalized. There was no difference in INR abnormality rate between tigecycline monotherapy versus combination therapy receiving cases (19/27-33% vs. 10/33-30% p:1).Conclusion: These data show that INR prolongation may develop as common as 34.6% during tigecycline therapy. Regular INR follow-up may be beneficial in cases receiving tigecycline.