Evaluation of moxifloxacin for the treatment of tuberculosis: 3 years of experience

Rapid drug tolerance and dramatic sterilizing effect of moxifloxacin monotherapy in a novel hollow-fiber model of intracellular Mycobacterium kansasii disease

Mycobacterium kansasii is the second most common mycobacterial cause of lung disease. Standard treatment consists of rifampin, isoniazid, and ethambutol for at least 12 months after negative sputum. Thus, shorter-duration therapies are needed. Moxifloxacin has good MICs for M. kansasii. However, good preclinical models to identify optimal doses currently are lacking. We developed a novel hollow fiber system model of intracellular M. kansasii infection. We indexed the efficacy of the standard combination regimen, which was a kill rate of -0.08 ± 0.05 log10 CFU/ml/day (r(2) = 0.99). We next performed moxifloxacin dose-effect and dose-scheduling studies at a half-life of 11.1 ± 6.47 h. Some systems also were treated with the efflux pump inhibitor reserpine. The highest moxifloxacin exposure, as well as lower exposures plus reserpine, sterilized the cultures by day 7. This suggests that efflux pump-mediated tolerance at low ratios of the area under the concentration-time curve from 0 to 24 h (AUC0 - 24) to MICs is an early bacterial defense mechanism but is overcome by higher exposures. The highest rate of moxifloxacin monotherapy sterilization was -0.82 ± 0.15 log10 CFU/ml/day (r(2) = 0.97). The moxifloxacin exposure associated with 80% of maximal kill (EC80) was an AUC0-24/MIC of 317 (the non-protein-bound moxifloxacin AUC0-24/MIC was 158.5). We performed Monte Carlo simulations of 10,000 patients in order to identify the moxifloxacin dose that would achieve or exceed the EC80. The simulations revealed an optimal moxifloxacin dose of 800 mg a day. The MIC susceptibility breakpoint at this dose was 0.25 mg/liter. Thus, moxifloxacin, at high enough doses, is suitable to study in patients for the potential to add rapid sterilization to the standard regimen.

Super-compact treatment with a high dose of moxifloxacin in patients with drug-resistant tuberculosis and its resistance mechanisms

The aim of this study was to investigate the curative effect and resistance mechanisms of high-dose moxifloxacin in the short-term treatment of multidrug-resistant tuberculosis. A total of 92 patients with multidrug-resistant tuberculosis were randomly selected and divided into groups A and B (n=46 per group). The two groups received moxifloxacin treatment with the same dose in total. Group A received a short course of treatment with moxifloxacin (0.6 g/day for 6 months), whereas group B received normal moxifloxacin treatment (0.4 g/day for 9 months). Sputum negative conversion, foci absorption, cavity closure and adverse reactions in the two groups were observed, and the drug resistance mechanism of tuberculosis to moxifloxacin treatment was investigated. Following the treatment, the curative rate of group A was 82.61%, and the curative rate of group B was 84.78%; there was no statistically significant difference between the two groups (P>0.05). The rates of sputum negative conversion, foci absorption and cavity closure were not significantly different between the two groups (P>0.05). However, the rates of reduction in peripheral white blood cell counts, liver function damage and adverse reactions, including symptoms affecting the gastrointestinal and nervous systems, were significantly lower in group A than in group B (P<0.05). The expression levels of the antigen-presenting functional molecules CD80 and CD40 on the surfaces of mononuclear cells were higher in group A than in group B (P<0.05), whereas the difference in HLA-DR expression between groups A and B was not significant (P>0.05). In conclusion, short-term treatment with a high dose of moxifloxacin is effective for multidrug-resistant tuberculosis, and its advantages are a reduction in the incidence of drug-associated adverse reactions and a lack of drug resistance.

Pharmacokinetics and safety of moxifloxacin in children with multidrug-resistant tuberculosis

BACKGROUND

Moxifloxacin is currently recommended at a dose of 7.5-10 mg/kg for children with multidrug-resistant (MDR) tuberculosis, but pharmacokinetic and long-term safety data of moxifloxacin in children with tuberculosis are lacking. An area under the curve (AUC) of 40-60 µg × h/mL following an oral moxifloxacin dose of 400 mg has been reported in adults.

METHODS

In a prospective pharmacokinetic and safety study, children 7-15 years of age routinely receiving moxifloxacin 10 mg/kg daily as part of multidrug treatment for MDR tuberculosis in Cape Town, South Africa, for at least 2 weeks, underwent intensive pharmacokinetic sampling (predose and 1, 2, 4, 8, and either 6 or 11 hours) and were followed for safety. Assays were performed using liquid chromatography-tandem mass spectrometry, and pharmacokinetic measures calculated using noncompartmental analysis.

RESULTS

Twenty-three children were included (median age, 11.1 years; interquartile range [IQR], 9.2-12.0 years); 6 of 23 (26.1%) were human immunodeficiency virus (HIV)-infected. The median maximum serum concentration (Cmax), area under the curve from 0-8 hours (AUC0-8), time until Cmax (Tmax), and half-life for moxifloxacin were 3.08 (IQR, 2.85-3.82) µg/mL, 17.24 (IQR, 14.47-21.99) µg × h/mL, 2.0 (IQR, 1.0-8.0) h, and 4.14 (IQR, 3.45-6.11), respectively. Three children, all HIV-infected, were underweight for age. AUC0-8 was reduced by 6.85 µg × h/mL (95% confidence interval, -11.15 to -2.56) in HIV-infected children. Tmax was shorter with crushed vs whole tablets (P = .047). Except in 1 child with hepatotoxicity, all adverse effects were mild and nonpersistent. Mean corrected QT interval was 403 (standard deviation, 30) ms, and no prolongation >450 ms occurred.

CONCLUSIONS

Children 7-15 years of age receiving moxifloxacin 10 mg/kg/day as part of MDR tuberculosis treatment have low serum concentrations compared with adults receiving 400 mg moxifloxacin daily. Higher moxifloxacin dosages may be required in children. Moxifloxacin was well tolerated in children treated for MDR tuberculosis.

Management of patients with multidrug-resistant/extensively drug-resistant tuberculosis in Europe: a TBNET consensus statement

The emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis (TB) substantially challenges TB control, especially in the European Region of the World Health Organization, where the highest prevalence of MDR/XDR cases is reported. The current management of patients with MDR/XDR-TB is extremely complex for medical, social and public health systems. The treatment with currently available anti-TB therapies to achieve relapse-free cure is long and undermined by a high frequency of adverse drug events, suboptimal treatment adherence, high costs and low treatment success rates. Availability of optimal management for patients with MDR/XDR-TB is limited even in the European Region. In the absence of a preventive vaccine, more effective diagnostic tools and novel therapeutic interventions the control of MDR/XDR-TB will be extremely difficult. Despite recent scientific advances in MDR/XDR-TB care, decisions for the management of patients with MDR/XDR-TB and their contacts often rely on expert opinions, rather than on clinical evidence.

This document summarises the current knowledge on the prevention, diagnosis and treatment of adults and children with MDR/XDR-TB and their contacts, and provides expert consensus recommendations on questions where scientific evidence is still lacking.

TBNET consensus statement on the management of patients with MDR/XDR-TB has been released in theEur Respir Jhttp://ow.ly/uizRD

Targeting multidrug-resistant tuberculosis (MDR-TB) by therapeutic vaccines

Tuberculosis (TB) has scourged humankind for millennia, and latent infection affects nearly one-third of today's world population. The emergence of multidrug-resistant (MDR)-TB is a major global threat and reflects treatment failure of drug-sensitive disease. MDR-TB management is a burden for patients and society; success rates are unacceptably low with prolonged treatment duration. Mycobacterium tuberculosis (Mtb) possesses the ability to transform into a dormant state in which it can persist in the face of antimicrobial treatment and host defense. This sub-population of persisters is largely responsible for lengthy and difficult treatment. Targeting persistent bacilli could eventually improve the treatment success rate (currently 50-65 %) and shorten duration of treatment. A subset of therapies in the pipeline, termed therapeutic vaccines, use the host immune response to attack Mtb. The historical occurrence of an exacerbated host response has resulted in a negative perception of therapeutic vaccines. Thus, a renewed concept of immunotherapy is needed. We review current perspectives of immunotherapy in MDR-TB based on the knowledge of TB immunology and briefly discuss the profiles of several therapeutic vaccine products.

Treatment of refractory Mycobacterium avium complex lung disease with a moxifloxacin-containing regimen

Moxifloxacin (MXF) has in vitro and in vivo activity against Mycobacterium avium complex (MAC) in experimental models. However, no data are available concerning its treatment effect in patients with MAC lung disease. The aim of this study was to evaluate the clinical efficacy of an MXF-containing regimen for the treatment of refractory MAC lung disease. Patients with MAC lung disease who were diagnosed between January 2002 and December 2011 were identified from our hospital database. We identified 41 patients who received MXF for ≥ 4 weeks for the treatment of refractory MAC lung disease. A total of 41 patients were treated with an MXF-containing regimen because of a persistent positive culture after at least 6 months of clarithromycin-based standardized antibiotic therapy. The median duration of antibiotic therapy before MXF administration was 410 days (interquartile range [IQR], 324 to 683 days). All patients had culture-positive sputum when MXF treatment was initiated. The median duration of MXF administration was 332 days (IQR, 146 to 547 days). The overall treatment success rate was 29% (12/41), and the median time to sputum conversion was 91 days (IQR, 45 to 190 days). A positive sputum acid-fast-bacillus smear at the start of treatment with MXF-containing regimens was an independent predictor of an unfavorable microbiological response. Our results indicate that MXF may improve treatment outcomes in about one-third of patients with persistently culture-positive MAC lung disease who fail to respond to clarithromycin-based standardized antibiotic treatment. Prospective studies are required to assess the clinical efficacy of MXF treatment for refractory MAC lung disease.

Moxifloxacin as an Alternative or Additive Therapy for Treatment of Pulmonary Tuberculosis

Objective:

To evaluate clinical studies on the role of moxifloxacin in the treatment of pulmonary tuberculosis (TB).

Data Sources:

A literature search was conducted using MEDLINE (1960-July 2011). Key search terms were moxifloxacin, BAY 12-8039, fluoroquinolones, and TB. References of review articles and of a Cochrane Review were also evaluated.

Study Selection and Data Extraction:

All articles published in English were evaluated. Prospective studies that evaluated the use of moxifloxacin in addition to or in substitution for first-line TB therapies were reviewed and included. Case series and retrospective studies were excluded.

Data Synthesis:

Four 8-week clinical trials were included. All had comparator regimens containing standard doses of rifampin, isoniazid, ethambutol, and pyrazinamide. Two evaluated the substitution of moxifloxacin for ethambutol, 1 evaluated the substitution of moxifloxacin for isoniazid, and 1 studied the addition of moxifloxacin to a standard regimen. The dose of moxifloxacin was 400 mg daily in all studies, but dosing frequency differed from 3 to 7 days per week. All used culture conversion at 8 weeks as the primary end point, although they coliected cultures at different times. Only 1 study found a significant difference in time to culture conversion at 8 weeks. One study found no significant difference at any point during the study. The other 2 studies found a significant difference in time to culture conversion at 4 and 6 weeks. In all trials, moxifloxacin was well tolerated, with nausea being the only significant adverse effect reported compared to the other arms of the studies.

Conclusions:

Although it cannot be stated definitively, available evidence suggests that moxifloxacin appears to be as effective as ethambutol and is possibly as effective as isoniazid In the treatment of pulmonary TB. Given the generally poor second-line options for the treatment of TB, moxifloxacin Is an attractive option as an alternative drug in TB treatment.