Efficacy of Moxifloxacin against Mycobacterium abscessus in Zebrafish Model in vivo.

OBJECTIVE: Moxifloxacin (MFX) shows good in vitro activity against Mycobacterium abscessus and can be a possible antibiotic therapy to treat M. abscessus infection; however, other studies have shown a lower or no activity. We aimed to evaluate MFX activity against M. abscessus using zebrafish (ZF) model in vivo. METHODS: A formulation of M. abscessus labeled with CM-Dil was micro-injected into ZF. Survival curves were determined by recording dead ZF every day. ZF were lysed, and colony-forming units (CFUs) were enumerated. Bacteria dissemination and fluorescence intensity in ZF were analyzed. Inhibition rates of MFX and azithromycin (AZM, positive control) were determined and compared. RESULTS: Significantly increased survival rate was observed with different AZM concentrations. However, increasing MFX concentration did not result in a significant decrease in ZF survival curve. No significant differences in bacterial burdens by CFU loads were observed between AZM and MFX groups at various concentrations. Bacterial fluorescence intensity in ZF was significantly correlated with AZM concentration. However, with increasing MFX concentration, fluorescence intensity decreased slightly when observed under fluorescence microscope. Transferring rates at various concentrations were comparable between the MFX and AZM groups, with no significant difference. CONCLUSION: MFX showed limited efficacy against M . abscessus in vivo using ZF model. Its activity in vivo needs to be confirmed.

Relative bioavailability of rifampicin in four Chinese fixed-dose combinations compared with rifampicin in free combinations.

BACKGROUND: Decreases in the bioavailability of rifampicin (RFP) can lead to the development of drug resistance and treatment failure. Therefore, we investigated the relative bioavailability of RFP from one four-drug fixed-dose combination (FDC; formulation A) and three two-drug FDCs (formulations B, C, and D) used in China, compared with RFP in free combinations of these drugs (reference), in healthy volunteers. METHODS: Eighteen and twenty healthy Chinese male volunteers participated in two open-label, randomized two-period crossover (formulations A and C) or one three-period crossover (formulations B and D) study, respectively. The washout period between treatments was 7 days. Bioequivalence was assessed based on 90% confidence intervals, according to two one-sided t-tests. All analyses were done with DAS 3.1.5 (Mathematical Pharmacology Professional Committee of China, Shanghai, China). RESULTS: Mean pharmacokinetic parameter values of RFP obtained for formulations A, B, C, and D products were 11.42 ± 3.41 µg/ml, 7.86 ± 5.78 µg/ml, 13.05 ± 6.80 µg/ml, and 16.18 ± 3.87 µg/ml, respectively, for peak plasma concentration (C max ), 91.43 ± 30.82 µg·h-1·ml-1 , 55.49 ± 37.58 µg·h-1·ml-1 , 96.50 ± 47.24 µg·h-1·ml-1 , 101.47 ± 33.07 µg·h-1·ml-1 , respectively, for area under the concentration-time curve (AUC 0-24 h ). CONCLUSIONS: Although the concentrations of RFP for formulations A, C, and D were within the reported acceptable therapeutic range, only formulation A was bioequivalent to the reference product. The three two-drug FDCs (formulations B, C and D) displayed inferior RFP bioavailability compared with the reference (Chinese Clinical Trials registration number: ChiCTR-TTRCC-12002451).