SETTING: Rifampicin (RMP) has been reported to reduce moxifloxacin (MFX) levels, which may interfere with the effectiveness of MFX in treating tuberculosis (TB).OBJECTIVE: To study the MFX-RMP interaction in patients receiving MFX with or without RMP as part of their anti-tuberculosis treatment regimen.DESIGN: Patients with pulmonary TB followed up by the Tuberculosis Out-patient Clinic of the Pulmonary Department, Aristotle University of Thessaloniki, Greece, who underwent treatment with MFX during the periods 1 May 2012-30 April 2014 and 1 January-31 March 2015, were included in the study. MFX levels were compared between 12 patients who were receiving RMP (Group 1) and 10 who were not (Group 2).RESULTS: The participants did not significantly differ in body mass index, days of MFX treatment or MFX dose/kg. Neither the peak concentration (Cmax) nor the 24 h area under the curve (AUC24) differed significantly between the two groups (Group 1, Cmax median 3.9 [range 1.9-4.5] mg/l; AUC24 29.1 [10-47.4] mg·h/l and Group 2, Cmax 4.1 [2-6.4] mg/l; AUC24 36.5 [14.6-54.2] mg·h/l).CONCLUSION: Although a decrease in MFX exposure was observed in the RMP-treated group, the effect was lower than previously reported in a real-life setting. The large variability observed in MFX pharmacokinetics in both groups may suggest the need for dose readjustment in some patients, regardless of RMP co-administration.