Levofloxacin treatment of active tuberculosis and the risk of adverse events

Background: Fluoroquinolones are commonly used in the treatment of tuberculosis (TB) for drug-sensitive patients who are intolerant to first-line antituberculous agents or who are infected with drug-resistant organisms. Despite increasing use of these agents, there is little information on their tolerance outside of clinical trial settings. Objectives: To compare overall rate of major adverse events associated with levofloxacin-containing regimen to standard therapy. Methods: Cases (levofloxacin-containing regimen) were matched by age and sex to their control subjects (standard first-line TB drugs). Eligible patients were identified from the provincial TB database from 2001 to 2004. Drug safety was assessed by evaluation of the nature of the adverse event, the likelihood of association with the study medications, and severity. Only major side effects, that is, those who had a severe or moderate adverse event that was categorized to be definitely; probably, or possibly related to the TB medications, were considered for the analysis. Results: During the 3-year study period, 102 patients received levofloxacin, and 358 patients received first-line agents for treatment of active TB. There were no significant differences between the two groups except for indication (82% of patients in the levofloxacin group had an antecedent adverse event to first-line TB drugs, whereas 18% received levofloxacin because of resistance) and concurrent use of first-line drugs (majority of patients in the levofloxacin arm were not receiving concurrent isoniazid or rifampin). The rate of any, major adverse event was almost half among those using levofloxacin as among those on standard therapies (rate ratio, 0.60; 95% confidence interval [CI], 0.44 to 0.82). After adjustment for the differences in exposure of concomitant medications, the rate of any major adverse event was similar between the levofloxacin and control arms (adjusted rate ratio, 0.83; 95% CI, 0.66 to 1.03). Furthermore, there was no difference between the levofloxacin and control arms with respect to CNS (adjusted rate ratio, 0.94; 95% CI, 0.61 to 1.43), GI tract (adjusted rate ratio, 0.81; 95% CI, 0.58 to 1.13), skin (adjusted rate ratio, 0.65; 95% CI, 0.38 to 1.10), or musculoskeletal (MSK) [adjusted rate ratio, 0.87, 95% CI, 0.48 to 1.60] related adverse events when adjusted for concomitant drugs. The results of the secondary analysis for the rate of major adverse events within the first 100 days were similar to the primary analysis. The time to the first major adverse event was similar between the levofloxacin group and the control group (adjusted hazards ratio, 1.01; 95% CI, 0.76 to 1.34). Conclusions: Concomitant use of a levofloxacin-containing regimen resulted in a similar rate of adverse events compared with conventional first-line regimens when used for treatment of active TB, despite a history of adverse events.