David C. Griffith

Pharmacokinetics and Safety of MP-376 (Levofloxacin Inhalation Solution) in Cystic Fibrosis Subjects

ABSTRACT The pharmacokinetics and tolerability of nebulized MP-376 (levofloxacin inhalation solution [Aeroquin]) were determined in cystic fibrosis (CF) subjects. Ten CF subjects received single 180-mg doses of two formulations of MP-376, followed by a multiple-dose phase of 240 mg once daily for 7 days. Serum and expectorated-sputum samples were assayed for levofloxacin content. Safety was evaluated following the single- and multiple-dose study phases. Nebulized MP-376 produced high concentrations of levofloxacin in sputum. The mean maximum plasma concentration (Cmax) ranged between 2,563 and 2,932 mg/liter for 180-mg doses of the 50- and 100-mg/ml formulations, respectively. After 7 days of dosing, the mean Cmax for the 240-mg dose was 4,691 mg/liter. The mean serum levofloxacin Cmax ranged between 0.95 and 1.28 for the 180-mg doses and was 1.71 for the 240-mg dose. MP-376 was well tolerated. Nebulized MP-376 produces high sputum and low serum levofloxacin concentrations. The pharmacokinetics, safety, and tolerability were similar for the two formulations. MP-376 240 mg (100 mg/ml) is being advanced into late-stage clinical development.

In Vitro Pharmacodynamics of Levofloxacin and Other Aerosolized Antibiotics under Multiple Conditions Relevant to Chronic Pulmonary Infection in Cystic Fibrosis

ABSTRACT The inhalational administration of antibiotics can provide high concentrations locally in the lungs of cystic fibrosis patients and, thus, can be useful for the treatment of chronic bacterial infections. The present study evaluated the in vitro activities of levofloxacin, ciprofloxacin, tobramycin, amikacin, and aztreonam against clinical isolates of Pseudomonas aeruginosa, Burkholderia cepacia complex, Stenotrophomonas maltophilia, Alcaligenes xylosoxidans, and Staphylococcus aureus from cystic fibrosis patients. Levofloxacin was the most potent antibiotic against all cystic fibrosis isolates tested, with MIC90s ranging from 8 to 32 μg/ml. Levofloxacin was more potent than the aminoglycosides and aztreonam against P. aeruginosa biofilms. Time-kill assays with drug concentrations achievable in sputum following aerosol administration showed that levofloxacin had the most rapid rate of killing among mucoid and nonmucoid isolates of P. aeruginosa. In contrast to tobramycin, the bactericidal activity of levofloxacin was not affected by sputum from cystic fibrosis patients. The results of the study show that the high concentrations of levofloxacin readily achievable in the lung following aerosol delivery may be useful for the management of pulmonary infections in patients with cystic fibrosis.

Effect of oxygen limitation on the in vitro activity of levofloxacin and other antibiotics administered by the aerosol route against Pseudomonas aeruginosa from cystic fibrosis patients

Studies have demonstrated that thickened mucous layers in the lungs of cystic fibrosis (CF) patients contain areas of low oxygen tension. These microaerophilic environments may reduce the activity of aerosol antibiotics used in the management of chronic infection in CF. The aim of this study was to compare the MICs of levofloxacin, tobramycin, amikacin, and aztreonam against Pseudomonas aeruginosa under reference and anaerobic conditions and evaluate the in vitro pharmacodynamics of levofloxacin under aerobic and hypoxic testing conditions. The MICs for 114 isolates of P. aeruginosa from CF patients were determined in cation-adjusted Mueller Hinton broth alone or supplemented with 1% potassium nitrate for anaerobic testing. Levofloxacin time-kill curves were performed under aerobic and hypoxic conditions using strains of P. aeruginosa with elevated efflux pump overexpression and/or target mutations. The MICs of nonmucoid or mucoid P. aeruginosa isolates to levofloxacin incubated under aerobic and anaerobic conditions were similar. In contrast, anaerobic incubation resulted in higher MICs for tobramycin, amikacin, and aztreonam among nonmucoid or mucoid isolates, with > or =4-fold increase in MICs for over 40% of the isolates. Time-kill curves performed in aerobic and hypoxic environments with levofloxacin concentrations attained in CF sputum demonstrated similar activity, approaching a maximum bactericidal effect within 10 min of exposure. Together, these results indicate that the activity of some antibiotics against P. aeruginosa is significantly reduced under conditions relevant to the CF lung environment. In contrast, levofloxacin maintains activity against P. aeruginosa under anaerobic or hypoxic conditions similar to those found in CF microaerophilic environments.

Efficacy of Aerosol MP-376, a Levofloxacin Inhalation Solution, in Models of Mouse Lung Infection Due to Pseudomonas aeruginosa

ABSTRACT Progressive respiratory failure due to Pseudomonas aeruginosa is the leading cause of morbidity and mortality in patients with cystic fibrosis. The pulmonary delivery of antimicrobial agents provides high concentrations of drug directly to the site of infection and attains pharmacokinetic-pharmacodynamic indices exceeding those which can be achieved with systemic dosing. MP-376 is a new formulation of levofloxacin that enables the safe aerosol delivery of high concentrations of drug to pulmonary tissues. In vivo studies were conducted to demonstrate the efficacy of MP-376 in models of mouse pulmonary infection. The superiority of aerosol dosing over systemic dosing was demonstrated in models of both acute and chronic lung infection. In a model of acute lung infection, aerosol treatment with MP-376 once or twice daily reduced the lung bacterial load to a greater extent than aerosol tobramycin or aztreonam did when they were administered at similar or higher doses. The bacterial killing by aerosol MP-376 observed in the lung in the model of acute pulmonary infection translated to improved survival (P < 0.05). In a model of chronic pulmonary infection, aerosol MP-376 had antimicrobial effects superior to those of aztreonam (P < 0.05) and effects similar to those of tobramycin (P > 0.05). In summary, these data show that aerosol MP-376 has in vivo activity when it is used to treat acute and chronic lung infections caused by P. aeruginosa.

Meropenem-RPX7009 Concentrations in Plasma, Epithelial Lining Fluid, and Alveolar Macrophages of Healthy Adult Subjects

ABSTRACT The steady-state concentrations of meropenem and the β-lactamase inhibitor RPX7009 in plasma, epithelial lining fluid (ELF), and alveolar macrophage (AM) concentrations were obtained in 25 healthy, nonsmoking adult subjects. Subjects received a fixed combination of meropenem (2 g) and RPX7009 (2 g) administered every 8 h, as a 3-h intravenous infusion, for a total of three doses. A bronchoscopy and bronchoalveolar lavage were performed once in each subject at 1.5, 3.25, 4, 6, or 8 h after the start of the last infusion. Meropenem and RPX7009 achieved a similar time course and magnitude of concentrations in plasma and ELF. The mean pharmacokinetic parameters ± the standard deviations of meropenem and RPX7009 determined from serial plasma concentrations were as follows: Cmax = 58.2 ± 10.8 and 59.0 ± 8.4 μg/ml, Vss = 16.3 ± 2.6 and 17.6 ± 2.6 liters; CL = 11.1 ± 2.1 and 10.1 ± 1.9 liters/h, and t1/2 = 1.03 ± 0.15 and 1.27 ± 0.21 h, respectively. The intrapulmonary penetrations of meropenem and RPX7009 were ca. 63 and 53%, respectively, based on the area under the concentration-time curve from 0 to 8 h (AUC0–8) values of ELF and total plasma concentrations. When unbound plasma concentrations were considered, ELF penetrations were 65 and 79% for meropenem and RPX7009, respectively. Meropenem concentrations in AMs were below the quantitative limit of detection, whereas median concentrations of RPX7009 in AMs ranged from 2.35 to 6.94 μg/ml. The results from the present study lend support to exploring a fixed combination of meropenem (2 g) and RPX7009 (2 g) for the treatment of lower respiratory tract infections caused by meropenem-resistant Gram-negative pathogens susceptible to the combination of meropenem-RPX7009.

Aerosol antibiotics: considerations in pharmacological and clinical evaluation

Increasing antibiotic resistance and lack of R&D productivity of new classes of antimicrobial agents directed against Gram-negative bacteria necessitate new approaches to maximize the efficacy of existing classes of drugs. Direct administration of drugs to the lung via the inhalational route provides for high concentrations at the target site of action in patients with pulmonary infections. The efficacy of aerosol antibiotic administration has been best demonstrated with aerosolized tobramycin in the management of chronic infections because of Pseudomonas aeruginosa in cystic fibrosis (CF) patients. Unfortunately, inconvenient regimens leading to poor patient adherence to therapy, and the increasing frequency of multidrug-resistant strains have necessitated the search for additional agents. Integration of aerosol science, PK-PD and clinical trial designs are important for the development and evaluation of these new aerosol agents in both chronic infections (e.g. CF and chronic obstructive pulmonary disease (COPD)) as well as acute infections (e.g. bacterial pneumonias). This review outlines important considerations and recent progress in this emerging area.

Phase 1 Study of the Safety, Tolerability, and Pharmacokinetics of the β-Lactamase Inhibitor Vaborbactam (RPX7009) in Healthy Adult Subjects

ABSTRACT Vaborbactam (formerly RPX7009) is a member of a new class of β-lactamase inhibitor with pharmacokinetic properties similar to those of many β-lactams, including carbapenems. The pharmacokinetics and safety of vaborbactam were evaluated in 80 healthy adult subjects in a first-in-human randomized, placebo-controlled, double-blind, sequential single- and multiple-ascending-dose study. A total of 10 dose cohorts were enrolled in the study, with 6 subjects randomized to receive 250 to 2,000 mg of vaborbactam and 2 subjects randomized to receive placebo in each cohort. Maximum concentrations for vaborbactam were achieved at the end of the 3-h infusion. Vaborbactam exposure (Cmax and area under the concentration-time curve [AUC]) increased in a dose-proportional manner following multiple doses. There was no evidence of accumulation with multiple doses, consistent with the terminal half-life of ∼2 h. Both the volume of distribution (Vss) and plasma clearance were independent of dose. For the 2,000-mg dose, the plasma clearance was 0.17 ± 0.03 liters/h, the AUC from 0 h to infinity (AUC0–∞) was 144.00 ± 13.90 mg · h/liter, and the Vss was 21.80 ± 2.26 mg · h/liter. Urinary recovery was 80% or greater over 48 h across all dose groups. No subjects discontinued the study due to adverse events (AEs), and no serious AEs (SAEs) were observed. All AEs were mild to moderate and similar among the vaborbactam- and placebo-treated subjects, with mild lethargy as the only unique AE reported with the high dose of vaborbactam. Overall, this study revealed the safety, tolerability, and pharmacokinetic profile of vaborbactam and formed the basis for advancement into patient studies in combination with meropenem, including treatment of patients with carbapenem-resistant Enterobacteriaceae (CRE) infections. (This study is registered at ClinicalTrials.gov under identifier NCT01751269.)

Levofloxacin reduces inflammatory cytokine levels in human bronchial epithelia cells: implications for aerosol MP-376 (levofloxacin solution for inhalation) treatment of chronic pulmonary infections

Inflammation resulting from chronic bacterial infection in the lung contributes to long-term pulmonary complications in chronic pulmonary infections such as cystic fibrosis. Aerosol administration of levofloxacin as in the form of the investigational formulation MP-376 results in higher concentrations in lung tissues that are higher than those that can be attained with oral or intravenous dosing of levofloxacin. The objective of this study was to evaluate the effect of high concentrations of levofloxacin achieved with aerosol administration of MP-376 on proinflammatory cytokine secretion by immortalized human bronchial epithelia cells in vitro. Additionally, we investigated the potential mechanisms of the immunomodulatory effect of levofloxacin. In vitro studies in human lung epithelial cell lines showed that levofloxacin led to a dose-related reduction in IL-6 and IL-8 concentrations, with 300 μg mL(-1) resulting in the reduction of levels of IL-6 by fourfold and IL-8 by twofold (P<0.05); in contrast, tobramycin increased IL-6 levels by 50%, but had no effect on IL-8. Levofloxacin treatment did not affect the cytokine mRNA level and nuclear factor-κB-dependent promoter activity. These findings suggest that high concentrations of levofloxacin obtained in pulmonary tissues following the administration of aerosol MP-376 may provide additional benefits in patients with chronic pulmonary infections that are independent of its antibacterial properties.

In Vivo Antibacterial Activity of RWJ-54428, a New Cephalosporin with Activity against Gram-Positive Bacteria

ABSTRACT RWJ-54428 (MC-02,479) is a new cephalosporin with activity against resistant gram-positive organisms, including methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, and penicillin-resistant Streptococcus pneumoniae. The in vivo efficacy of RWJ-54428 was evaluated against gram-positive bacteria in four mouse models of infection. RWJ-54428 was effective in vivo against methicillin-susceptible and -resistant S. aureus in a mouse model of sepsis, with 50% effective doses being similar to those of vancomycin. In a single-dose neutropenic mouse thigh model of infection, RWJ-54428 at 30 mg/kg of body weight showed activity similar to that of vancomycin at 30 mg/kg against a strain of methicillin-resistant S. aureus. RWJ-54428 also showed a prolonged in vivo postantibiotic effect in this model. In a mouse model of pneumonia due to a penicillin-susceptible strain of Streptococcus pneumoniae, RWJ-54428 displayed efficacy and potency superior to those of penicillin G and cefotaxime. In a mouse model of pyelonephritis due to Enterococcus faecalis, RWJ-54428 had bactericidal effects similar to those of vancomycin and ampicillin, but at two- to threefold lower total daily doses. These studies show that RWJ-54428 is active in experimental mouse models of infection against gram-positive organisms, including strains resistant to earlier cephalosporins and penicillin G.

Effect of Meropenem-Vaborbactam vs Piperacillin-Tazobactam on Clinical Cure or Improvement and Microbial Eradication in Complicated Urinary Tract Infection: The TANGO I Randomized Clinical Trial

Importance Meropenem-vaborbactam is a combination carbapenem/beta-lactamase inhibitor and a potential treatment for severe drug-resistant gram-negative infections. Objective To evaluate efficacy and adverse events of meropenem-vaborbactam in complicated urinary tract infection (UTI), including acute pyelonephritis. Design, Setting, and Participants Phase 3, multicenter, multinational, randomized clinical trial (TANGO I) conducted November 2014 to April 2016 and enrolling patients (≥18 years) with complicated UTI, stratified by infection type and geographic region. Interventions Eligible patients were randomized 1:1 to receive meropenem-vaborbactam (2g/2g over 3 hours; nu2009=u2009274) or piperacillin-tazobactam (4g/0.5g over 30 minutes; nu2009=u2009276) every 8 hours. After 15 or more doses, patients could be switched to oral levofloxacin if they met prespecified criteria for improvement, to complete 10 days of total treatment. Main Outcomes and Measures Primary end point for FDA criteria was overall success (clinical cure or improvement and microbial eradication composite) at end of intravenous treatment in the microbiologic modified intent-to-treat (ITT) population. Primary end point for European Medicines Agency (EMA) criteria was microbial eradication at test-of-cure visit in the microbiologic modified ITT and microbiologic evaluable populations. Prespecified noninferiority margin was −15%. Because the protocol prespecified superiority testing in the event of noninferiority, 2-sided 95% CIs were calculated. Results Among 550 patients randomized, 545 received study drug (mean age, 52.8 years; 361 [66.2%] women; 374 [68.6%] in the microbiologic modified ITT population; 347 [63.7%] in the microbiologic evaluable population; 508 [93.2%] completed the trial). For the FDA primary end point, overall success occurred in 189 of 192 (98.4%) with meropenem-vaborbactam vs 171 of 182 (94.0%) with piperacillin-tazobactam (difference, 4.5% [95% CI, 0.7% to 9.1%]; Pu2009<u2009.001 for noninferiority). For the EMA primary end point, microbial eradication in the microbiologic modified ITT population occurred in 128 of 192 (66.7%) with meropenem-vaborbactam vs 105 of 182 (57.7%) with piperacillin-tazobactam (difference, 9.0% [95% CI, −0.9% to 18.7%]; Pu2009<u2009.001 for noninferiority); microbial eradication in the microbiologic evaluable population occurred in 118 of 178 (66.3%) vs 102 of 169 (60.4%) (difference, 5.9% [95% CI, −4.2% to 16.0%]; Pu2009<u2009.001 for noninferiority). Adverse events were reported in 106 of 272 (39.0%) with meropenem-vaborbactam vs 97 of 273 (35.5%) with piperacillin-tazobactam. Conclusions and Relevance Among patients with complicated UTI, including acute pyelonephritis and growth of a baseline pathogen, meropenem-vaborbactam vs piperacillin-tazobactam resulted in a composite outcome of complete resolution or improvement of symptoms along with microbial eradication that met the noninferiority criterion. Further research is needed to understand the spectrum of patients in whom meropenem-vaborbactam offers a clinical advantage. Trial Registration clinicaltrials.gov Identifier: NCT02166476