Pharmacokinetics of a once-daily oral dose of moxifloxacin (Bay 12-8039), a new enantiomerically pure 8-methoxy quinolone

Evaluation of the Effect of Momelotinib on Cardiac Repolarization: A Thorough QT Study

A randomized, partially blinded, placebo-controlled, crossover study in 48 healthy adults assessed the effect of momelotinib on the heart rate-corrected QT interval (QTc) using the Fridericia formula (QTcF). QTc was evaluated for momelotinib 200 mg (therapeutic dose), momelotinib 800 mg (supratherapeutic dose), moxifloxacin 400 mg (positive control), and placebo. Pharmacokinetic profiles of momelotinib and its active metabolite M21 were evaluated. Momelotinib did not prolong QTcF, as the upper bounds of the 2-sided 90% confidence intervals (CIs) for the mean difference between doses of momelotinib and placebo were <10 milliseconds at all time points. The lower limit of the 2-sided 98% CI for the mean difference in QTcF between moxifloxacin versus placebo was >5 milliseconds at 2, 3, and 4 hours after dosing, demonstrating assay sensitivity. There was no positive relationship between momelotinib plasma concentrations and QTcF. Adverse events (AEs) were more frequent with the supratherapeutic dose of momelotinib, but none were considered severe. There were no deaths, serious AEs, or AEs leading to study discontinuation. Neither therapeutic nor supratherapeutic doses of momelotinib led to clinically significant effects on the QTc interval, supporting a negative finding for QTc prolongation from this thorough QT study.

Recent Biochemical Advances in Antitubercular Drugs: Challenges and Future

Tuberculosis (TB) is one of the leading causes of death world-wide after AIDS. It infects around one-third of global population and approximately two million people die annually from this disease because it is a very contagious disease spread by Mycobacterium tuberculosis. The increasing number of drug-resistant strains and the failure of conventional treatments against this strain are the challenges of the coming decades. New therapeutic techniques aim to confirm cure without deterioration, to reduce deaths, contagions and the formation of drug-resistant strains. A plethora of new diagnostic tests are available to diagnose the active tuberculosis, screen latent M. tuberculosis infection, and to identify drug-resistant strains of M. tuberculosis. When effective prevention strategies do not prevail, high rates of early case detection and successive cures to control TB emergence would not be possible. In this review, we discussed the structural features of M. tuberculosis, Multi drug resistance tuberculosis (MDR-TB), extremely drug-resistant tuberculosis (XDR-TB), the mechanism of M. tuberculosis infection, the mode of action of first and second-line antitubercular drugs, the mechanism of resistance to the existing drugs, compounds in preclinical and clinical trial and drugs presently available for the treatment of tuberculosis. Moreover, the new diagnostic techniques to detect M. tuberculosis are also discussed in this review.

Moxifloxacin monotherapy for treatment of uncomplicated pelvic inflammatory disease: A systematic review and meta-analysis with trial sequential analysis of randomized controlled trials

PURPOSE

The aim of this study was to evaluate the efficacy and safety of moxifloxacin monotherapy for the treatment of uncomplicated pelvic inflammatory disease (uPID).

METHODS

The literatures from PubMed, ScienceDirect, Google Scholar, Cochrane library and the http://clinicaltrials.gov/ were retrieved until February 2023. Only randomized controlled trials (RCTs) comparing the efficacy and safety of moxifloxacin with other antibiotics for treating uPID were included. The primary outcomes were clinical cure rate (CCR), bacteriological success rates (BSR) and risk of drug-related adverse events (AEs). We used random-effects modelled meta-analysis, trial sequential analysis, and the Grading of Recommendations Assessment, Development, and Evaluation. This study was registered in the International Prospective Register of Systematic Reviews (registration number: CRD42023428751).

RESULTS

A total of four RCTs that enrolled 3201 women patients with uPID were included. In the per-protocol populations, no significant difference was observed between patients given moxifloxacin and those given other antibiotics with regard to CCR at test-of-cure (TOC) (2485 patients, odds ratio [OR] = 0.84, 95% confidence interval [CI] 0.68-1.04, p = 0.12). Similarly, there was no statistically significant difference between patients given moxifloxacin and those given other antibiotics in terms of BSR at TOC (471 patients, OR = 1.17, 95% CI 0.70-1.96, p = 0.56) in the microbiologically valid population. However, drug-related AEs occurred less frequently with moxifloxacin than with other antibiotics (2973 patients, OR = 0.74, 95% CI 0.64-0.86, p < 0.0001), especially gastrointestinal AEs (2973 patients, OR = 0.59, 95% CI 0.47-0.74, p < 0.00001).

CONCLUSIONS

In the treatment of uPID, moxifloxacin monotherapy can achieve similar efficacy as other combination therapy regimens. Moreover, moxifloxacin had a better safety profile than that of comparators. Based on its additional advantages (i.e., better safety profile, no dosage adjustment and better compliance), moxifloxacin may be a more fascinating option compared with the currently used regimens.

Key Factors in Effective Patient-Tailored Dosing of Fluoroquinolones in Urological Infections: Interindividual Pharmacokinetic and Pharmacodynamic Variability

Fluoroquinolones (FQs) are a critical group of antimicrobials prescribed in urological infections as they have a broad antimicrobial spectrum of activity and a favorable tissue penetration at the site of infection. However, their clinical practice is not problem-free of treatment failure, risk of emergence of resistance, and rare but important adverse effects. Due to their critical role in clinical improvement, understanding the dose-response relation is necessary to optimize the effectiveness of FQs therapy, as it is essential to select the right antibiotic at the right dose for the right duration in urological infections. The aim of this study was to review the published literature about inter-individual variability in pharmacological processes that can be responsible for the clinical response after empiric dose for the most commonly prescribed urological FQs: ciprofloxacin, levofloxacin, and moxifloxacin. Interindividual pharmacokinetic (PK) variability, particularly in elimination, may contribute to treatment failure. Clearance related to creatinine clearance should be specifically considered for ciprofloxacin and levofloxacin. Likewise, today, undesired interregional variability in FQs antimicrobial activity against certain microorganisms exists. FQs pharmacology, patient-specific characteristics, and the identity of the local infecting organism are key factors in determining clinical outcomes in FQs use.

Activity of Moxifloxacin Against Biofilms Formed by Clinical Isolates of Staphylococcus aureus Differing by Their Resistant or Persister Character to Fluoroquinolones

Staphylococcus aureus biofilms are poorly responsive to antibiotics. Underlying reasons include a matrix effect preventing drug access to embedded bacteria, or the presence of dormant bacteria with reduced growth rate. Using 18 clinical isolates previously characterized for their moxifloxacin-resistant and moxifloxacin-persister character in stationary-phase culture, we studied their biofilm production and matrix composition and the anti-biofilm activity of moxifloxacin. Biofilms were grown in microtiter plates and their abundance quantified by crystal violet staining and colony counting; their content in polysaccharides, extracellular DNA and proteins was measured. Moxifloxacin activity was assessed after 24 h of incubation with a broad range of concentrations to establish full concentration-response curves. All clinical isolates produced more biofilm biomass than the reference strain ATCC 25923, the difference being more important for those with high relative persister fractions to moxifloxacin, most of which being also resistant. High biofilm producers expressed icaA to higher levels, enriching the matrix in polysaccharides. Moxifloxacin was less potent against biofilms from clinical isolates than from ATCC 25923, especially against moxifloxacin-resistant isolates with high persister fractions, which was ascribed to a lower concentration of moxifloxacin in these biofilms. Time-kill curves in biofilms revealed the presence of a moxifloxacin-tolerant subpopulation, with low multiplication capacity, whatever the persister character of the isolate. Thus, moxifloxacin activity depends on its local concentration in biofilm, which is reduced in most isolates with high-relative persister fractions due to matrix effects, and insufficient to kill resistant isolates due to their high MIC.

Prediction of Moxifloxacin Concentrations in Tuberculosis Patient Populations by Physiologically Based Pharmacokinetic Modeling

Moxifloxacin has an important role in the treatment of tuberculosis (TB). Unfortunately, coadministration with the cornerstone TB drug rifampicin results in suboptimal plasma exposure. We aimed to gain insight into the moxifloxacin pharmacokinetics and the interaction with rifampicin. Moreover, we provided a mechanistic framework to understand moxifloxacin pharmacokinetics. We developed a physiologically based pharmacokinetic model in Simcyp version 19, with available and newly generated in vitro and in vivo data, to estimate pharmacokinetic parameters of moxifloxacin alone and when administered with rifampicin. By combining these strategies, we illustrate that the role of P-glycoprotein in moxifloxacin transport is limited and implicate MRP2 as transporter of moxifloxacin-glucuronide followed by rapid hydrolysis in the gut. Simulations of multiple dose area under the plasma concentration-time curve (AUC) of moxifloxacin (400 mg once daily) with and without rifampicin (600 mg once daily) were in accordance with clinically observed data (predicted/observed [P/O] ratio of 0.87 and 0.80, respectively). Importantly, increasing the moxifloxacin dose to 600 mg restored the plasma exposure both in actual patients with TB as well as in our simulations. Furthermore, we extrapolated the single dose model to pediatric populations (P/O AUC ratios, 1.04-1.52) and the multiple dose model to children with TB (P/O AUC ratio, 1.51). In conclusion, our combined approach resulted in new insights into moxifloxacin pharmacokinetics and accurate simulations of moxifloxacin exposure with and without rifampicin. Finally, various knowledge gaps were identified, which may be considered as avenues for further physiologically based pharmacokinetic refinement.

Determination of fluoroquinolones in dried plasma spots by using microwave-assisted extraction coupled to ultra-high performance liquid chromatography-tandem mass spectrometry for therapeutic drug monitoring

Therapeutic drug monitoring is important for achieving desirable outcomes in tuberculosis treatment. In this study, microwave-assisted extraction was used to extract levofloxacin, ciprofloxacin, and moxifloxacin from dried plasma spots for subsequent detection and quantification with ultra-high performance liquid chromatography-tandem mass spectrometry. Dried plasma spotting was performed by dropping 15 μL of plasma on a protein saver card. Analyte extraction was performed with microwave-assisted extraction at 400 W for 40 s in 90 % methanol. Samples were analyzed with a core-shell C18 column (100 mm × 2.1 mm, 2.6 μm, 100 Å). Multiple reaction monitoring was used and the ion source was operated in positive electrospray ionization mode. The correlation coefficients of the calibration curves were > 0.999 for all three drugs over a range of 0.2-20 μg/mL. The intraday precision (n = 5) of the peak area ratios of the analyte to the internal standard was between 1.3 and 4.0 % relative standard deviation (RSD). The intraday accuracy ranged from 93.6-106.9%. The interday (n = 3) precision of the peak area ratios ranged from 1.9 to 8.8 % RSD, and the accuracy ranged from 94.9-107.1%. Regarding clinical application, the quantification results for moxifloxacin from dried plasma spots (DPSs) were strongly similar to the results from the plasma samples, which showed that Pearson's rho > 0.949. The validation and application results showed that the developed method can be used as an efficient analytical technique for therapeutic drug monitoring of fluoroquinolones for patients with tuberculosis.

Pharmacokinetics, Safety, and Tolerability of Single-Dose Intravenous Moxifloxacin in Pediatric Patients: Dose Optimization in a Phase 1 Study

The pharmacokinetics, safety, and tolerability of a single dose of moxifloxacin were characterized in 31 pediatric patients already receiving antibiotics for a suspected or proven infection in an open-label phase 1 study. A dosing strategy for each age cohort (Cohort 1: ≥6 years to ≤14 years; Cohort 2: ≥2 years to <6 years; Cohort 3: >3 month to <2 years) was developed using physiology-based pharmacokinetic modeling combined with a stepwise dosing scheme to obtain a similar exposure to adults receiving 400 mg of moxifloxacin. Doses, adjusted to body weight and age, were gradually escalated from 5 mg/kg in Cohort 1 to 10 mg/kg in Cohort 3 based on interim analysis of the pharmacokinetic and safety data. Plasma and urine samples before and after the 60-minute infusion were collected for the analysis of moxifloxacin and its metabolites using a validated high-pressure liquid chromatography assay with tandem mass spectrometry. Moxifloxacin and metabolite concentrations in plasma were within the ranges observed in adults; however, clearance of all analytes was lower in pediatric patients compared with adults. Population pharmacokinetic analyses using the achieved exposure levels in the 3 age cohorts (with known body weight and clearance) predicted similar efficacy and safety profiles to adults. Moxifloxacin was well tolerated in all pediatric age cohorts. Adverse events related to moxifloxacin were mild or moderate in intensity and showed no correlation with increased weight-adjusted doses. Our findings guided the selection of age-appropriate clinical doses for a subsequent phase 3 clinical trial in pediatric patients with complicated intra-abdominal infections.

Nanoparticle Formulation of Moxifloxacin and Intramuscular Route of Delivery Improve Antibiotic Pharmacokinetics and Treatment of Pneumonic Tularemia in a Mouse Model

Francisella tularensis causes a serious and often fatal infection, tularemia. We compared the efficacy of moxifloxacin formulated as free drug vs disulfide snap-top mesoporous silica nanoparticles (MSNs) in a mouse model of pneumonic tularemia. We found that MSN-formulated moxifloxacin was more effective than free drug and that the intramuscular and subcutaneous routes were markedly more effective than the intravenous route. Measurement of tissue silica levels and fluorescent flow cytometry assessment of colocalization of MSNs with infected cells revealed that the enhanced efficacy of MSNs and the intramuscular route of delivery was not due to better delivery of MSNs to infected tissues or cells. However, moxifloxacin blood levels demonstrated that the nanoparticle formulation and intramuscular route provided the longest half-life and longest time above the minimal inhibitory concentration. Thus, improved pharmacokinetics are responsible for the greater efficacy of nanoparticle formulation and intramuscular delivery compared with free drug and intravenous delivery.

Liquid chromatography-tandem mass spectrometry for the quantification of moxifloxacin, ciprofloxacin, daptomycin, caspofungin, and isavuconazole in human plasma

A simple and precise ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed for the simultaneous analysis of five anti-infective agents used to treat severe infections [three antibiotics (daptomycin, moxifloxacin, ciprofloxacin) and two antifungals (isavuconazole, caspofungin)] in human plasma. Sample preparation was based on protein precipitation with ice cold methanol. All five agents were analyzed with the corresponding isotopically labeled internal standards. All analytes were detected in multiple reactions monitoring (MRM) using API 4000 triple-quadrupole mass spectrometer with electrospray (ESI) source operating in positive mode. The calibration curves were linear over the selected ranges (r > 0.99). The method is precise and accurate with a total run time of 5.5 min. Accuracy of all target analytes ranged between 95.9-116.6%, measured with an imprecision of less than 10.8%. The lower limit of quantification was 1.25 mg/L for caspofungin, 0.3125 mg/L for isavuconazole, 3.125 mg/L for daptomycin, 0.075 mg/L for ciprofloxacin, and 0.1875 mg/L for moxifloxacin. The successful application of the method in patient samples proved its suitability for the medical surveillance of antimicrobial therapy in intensive care units as well as to other pharmacokinetic studies.

Population pharmacokinetics of moxifloxacin and its concentration-QT interval relationship modeling in Chinese healthy volunteers

Moxifloxacin (MX) is an 8-methoxyquinolone antimicrobial drug, which is often used as a positive control in thorough QT (TQT) studies. In the present study we established the population pharmacokinetics model of MX and the relationship of MX concentrations with the QT and various corrected QT (QTc) intervals, and compared the results with other ethnicities. The MX data used for modeling were obtained from a published TQT interval prolongation study of antofloxacin with MX as the positive control. In this four-period crossover study, 24 adult Chinese healthy volunteers received either 200 or 400 mg of oral antofloxacin once daily, 400 mg of MX, or a placebo. Population concentration-effect models were used to investigate the relationship between MX concentrations and QT interval prolongation, baseline-adjusted QTc (ΔQTc), or ΔQTc adjusted with time-matched placebo corrections (ΔΔQTc). The influencing factors of MX PK and the concentration-QTc relationship were determined through covariate screening. Simulation studies were conducted in R2.30 by using the final model with the estimated population mean and intra-individual and inter-individual variability. The estimated pharmacokinetic parameters and the estimated slope of the MX concentration-QT/ΔQTc/ΔΔQTc relationship were described using models and were compared to results for other ethnicities from the literature. We showed that the population pharmacokinetic parameter estimates for total plasma clearance (CL/F), the volume of distribution of central compartment (Vc/F), the distributional clearance in plasma (Q), the volume of distribution of peripheral compartment (Vp/F), and the absorption rate constant (Ka) were 8.22 L/h, 104 L, 3.98 L/h, 37.7 L, and 1.81 1/h, respectively. There was no significant covariate included in the final model. QT interval prolongation of MX estimates ranging from 9.77 to 12.91 ms at the mean average maximum concentration of MX (4.36 μg/mL) and a mean slope ranging from 2.33 to 2.96 ms per μg/mL. In conclusion, no ethnic differences were observed for the MX pharmacokinetic parameters and QT interval prolongation.

A Review of Moxifloxacin for the Treatment of Drug-Susceptible Tuberculosis

Moxifloxacin, an 8-methoxy quinolone, is an important drug in the treatment of multidrug-resistant tuberculosis and is being investigated in novel drug regimens with pretomanid, bedaquiline, and pyrazinamide, or rifapentine, for the treatment of drug-susceptible tuberculosis. Early results of these studies are promising. Although current evidence does not support the use of moxifloxacin in treatment-shortening regimens for drug-susceptible tuberculosis, it may be recommended in patients unable to tolerate standard first-line drug regimens or for isoniazid monoresistance. Evidence suggests that the standard 400-mg dose of moxifloxacin used in the treatment of tuberculosis may be suboptimal in some patients, leading to worse tuberculosis treatment outcomes and emergence of drug resistance. Furthermore, a drug interaction with the rifamycins results in up to 31% reduced plasma concentrations of moxifloxacin when these are combined for treatment of drug-susceptible tuberculosis, although the clinical relevance of this interaction is unclear. Moxifloxacin exhibits extensive interindividual pharmacokinetic variability. Higher doses of moxifloxacin may be needed to achieve drug exposures required for improved clinical outcomes. Further study is, however, needed to determine the safety of proposed higher doses and clinically validated targets for drug exposure to moxifloxacin associated with improved tuberculosis treatment outcomes. We discuss in this review the evidence for the use of moxifloxacin in drug-susceptible tuberculosis and explore the role of moxifloxacin pharmacokinetics, pharmacodynamics, and drug interactions with rifamycins, on tuberculosis treatment outcomes when used in first-line tuberculosis drug regimens.

Moxifloxacin Concentration and Proteomic Analysis of Aqueous Humor in Human Uveitis Associated with Oral Moxifloxacin Therapy

PURPOSE

The aim was to report the aqueous humor moxifloxacin concentration and proteome profile of an individual with bilateral uveitis-like syndrome with pigment dispersion.

METHODS

Multiple reactions monitoring mass spectrometry quantified the aqueous concentration of moxifloxacin in the affected individual. Shotgun proteomic analysis performed via liquid chromatography tandem mass spectrometry (LC-MS/MS) defined the protein profile in the affected individual and unaffected control samples.

RESULTS

Moxifloxacin was present at higher than expected levels in aqueous humor 18 days following oral administration. One-third of the proteins were identified by significantly lower spectral counts in the aqueous of the individual with moxifloxacin associated uveitis compared to the unaffected control.

CONCLUSION

Moxifloxacin was detected in aqueous humor 18 days following the completion of oral administration. These results suggest that moxifloxacin toxicity may be responsible for the uveitis-like syndrome with pigment dispersion syndrome induced by moxifloxacin therapy.

New tuberculosis drug leads from naturally occurring compounds

Tuberculosis (TB) continues to be a significant cause of mortality and morbidity worldwide. An estimated 2 billion individuals are infected with Mycobacterium tuberculosis and annually there are approximately 10 million new cases of clinical TB and 1.5 million deaths. Currently available drugs and vaccines have had no significant impact on TB control. In addition, the emergence of drug resistant TB is considered a public health crisis, with some strains now resistant to all available drugs. Unfortunately, the growing burden of antibiotic resistance is coupled with decreased effort in the development of new antibiotics. Natural sources are attractive starting points in the search for anti-tubercular drugs because they are extremely rich in chemical diversity and have privileged antimicrobial activity. This review will discuss recent advances in the development of TB drug leads from natural products, with a particular focus on anti-mycobacterial compounds in late-stage preclinical and clinical development.

The role of moxifloxacin in tuberculosis therapy

Tuberculosis (TB) remains a global threat with more than 9 million new infections. Treatment remains difficult and there has been no change in the duration of the standard regimen since the early 1980s. Moreover, many patients are unable to tolerate this treatment and discontinue therapy, increasing the risk of resistance. There is a growing tide of multidrug resistance and few effective antibiotics to tackle the problem. Since the turn of the millennium there has been a surge in interest in developing new therapies for TB and a number of new drugs have been developed. In this review the repurposing of moxifloxacin, an 8-methoxy-fluoroquinolone, for TB treatment is discussed. The evidence that underpins the development of this agent is reviewed. The results of the recently completed phase III trials are summarised and the reasons for the unexpected outcome are explored. Finally, the design of new trials that incorporate moxifloxacin, and that address both susceptible disease and multidrug resistance, is described.

Pharmacokinetics and Pharmacodynamics of the New Quinolones

In this review, the authors describe the pharmacokinetic (PK) and pharmacodynamic (PD) characteristics of the new quinolones (levofloxacin, gatifloxacin, moxifloxacin, gemifloxacin, and garenoxacin) and discuss their implications on adequate therapy of patients with respiratory infections. The newer quinolones display excellent bioavailability and have longer serum half-lives than ciprofloxacin. In addition, they have the ability to concentrate in respiratory tract tissues and fluids at levels that exceed serum-drug concentrations. Also, the newer quinolones exhibit broad-spectrum activity against both susceptible and resistant organisms. Those favorable PK/PD properties make the new quinolones an attractive therapeutic alternative to traditional agents for common respiratory infections. Understanding the PK/PD of quinolone antibiotics can facilitate selection of optimal regimens to hasten response, prevent treatment failures, and minimize the development of resistance.

Focus on JNJ-Q2, a novel fluoroquinolone, for the management of community-acquired bacterial pneumonia and acute bacterial skin and skin structure infections

JNJ-Q2 is a novel, fifth-generation fluoroquinolone that has excellent in vitro and in vivo activity against a variety of Gram-positive and Gram-negative organisms. In vitro studies indicate that JNJ-Q2 has potent activity against pathogens responsible for acute bacterial skin and skin structure infections (ABSSSI) and community-acquired bacterial pneumonia (CABP), such as Staphylococcus aureus and Streptococcus pneumoniae. JNJ-Q2 also has been shown to have a higher barrier to resistance compared to other agents in the class and it remains highly active against drug-resistant organisms, including methicillin-resistant S. aureus, ciprofloxacin-resistant methicillin-resistant S. aureus, and drug-resistant S. pneumoniae. In two Phase II studies, the efficacy of JNJ-Q2 was comparable to linezolid for ABSSSI and moxifloxacin for CABP. Furthermore, JNJ-Q2 was well tolerated, with adverse event rates similar to or less than other fluoroquinolones. With an expanded spectrum of activity and low potential for resistance, JNJ-Q2 shows promise as an effective treatment option for ABSSSI and CABP. Considering its early stage of development, the definitive role of JNJ-Q2 against these infections and its safety profile will be determined in future Phase III studies.

Absence of ethnic differences in the pharmacokinetics of moxifloxacin, simvastatin, and meloxicam among three East Asian populations and Caucasians

Aim

To examine whether strict control of clinical trial conditions could reduce apparent differences of pharmacokinetic (PK) parameters among ethnic groups.

Methods

Open‐label, single dose PK studies of moxifloxacin, simvastatin and meloxicam were conducted in healthy male subjects from three East Asian populations (Japanese, Chinese and Koreans) and one Caucasian population as a control. These three drugs were selected because differences in PK parameters have been reported, even though the backgrounds of these East Asian populations are similar. Moxifloxacin (400 mg) was administered orally to 20 subjects, and plasma and urine levels of moxifloxacin and its metabolite (M2) were measured. Simvastatin (20 mg) was given to 40 subjects, and plasma levels of simvastatin and simvastatin acid were measured. Meloxicam (7.5 mg) was given to 30 subjects and its plasma concentration was determined. Intrinsic factors (polymorphism of UGT1A1 for moxifloxacin, SLCO1B1 for simvastatin, and CYP2C9 for meloxicam) were also examined.

Results

AUC_inf values for moxifloxacin, simvastatin and meloxicam showed no significant differences among the East Asian groups. C_max values of moxifloxacin and simvastatin, but not meloxicam, showed significant differences. There were no significant differences of data for M2 or simvastatin acid. Genetic analysis identified significant differences in the frequencies of relevant polymorphisms, but these differences did not affect the PK parameters observed.

Conclusions

Although there were some differences in PK parameters among the three East Asian groups, the present study performed under strictly controlled conditions did not reproduce the major ethnic differences observed in previous studies.

Effect of Retosiban on Cardiac Repolarization in a Randomized, Placebo- and Positive-controlled, Crossover Thorough QT/QTc Study in Healthy Men and Women

PURPOSE

Retosiban is a small molecule oxytocin receptor antagonist that is under evaluation in clinical studies for treatment of spontaneous preterm labor. A Thorough QT/QTc study was conducted to evaluate the effect of retosiban on cardiac repolarization according to International Conference on Harmonization E14 guidance. This was a randomized, placebo- and positive-controlled, single-dose, crossover study of healthy men and women.

METHODS

All study participants received a 100 mg dose of retosiban (therapeutic target exposure), a 800 mg dose of retosiban (supratherapeutic target exposure), a 400 mg dose of moxifloxacin (positive control), and placebo with an appropriate washout. Holter monitoring data at baseline (predose) and at 13 subsequent time points during the next 24 hours were extracted and manually read by a central ECG reader who was blinded to the treatment assignment and corrected for heart rate by using the Fridericia formula (QTcF). A linear exposure-QTc response model was developed: ΔΔQTcF=RI+Cp,R⋅RS+MI+Cp,M⋅MS, where RI and MI are intercept terms for retosiban and moxifloxacin, respectively, RS and MS are slope terms for retosiban and moxifloxacin, respectively, and Cp,R and Cp,M are plasma concentrations for retosiban and moxifloxacin, respectively.

FINDINGS

A total of 52 healthy men (n = 27) and women (n = 25), with a mean age of 32 years, were enrolled in the study, and 43 (83%) completed all treatment periods and assessments. Mean placebo-corrected change from baseline QT (ΔΔQTcF) for the 2 retosiban dose groups revealed statistically significant decreases in ΔΔQTcF between 2 and 3 hours after administration, reaching a value of -2.5 msec for both retosiban dose groups. The 400 mg moxifloxacin group had a statistically significant increase in the ΔΔQTcF value at 0.75 hours after administration, reaching a maximal increase of 11.10 msec at 4 hours after administration. Results of the exposure-QTc response modeling revealed that there was no significant effect of retosiban on the ΔΔQTcF at therapeutic exposures. For the supratherapeutic exposure of retosiban, there was a slight negative effect, with a mean decrease of -3.05 msec. The moxifloxacin arm had a mean increase in ΔΔQTcF of 10.7 msec.

IMPLICATIONS

At therapeutic and supratherapeutic exposures, retosiban had no significant effect on cardiac repolarization, as estimated by the ΔΔQTcF. However, both doses of retosiban had a minor shortening effect. This is not considered to be clinically significant. CLINICALTRIALS.

GOV IDENTIFIER

NCT01702376.

Four-month moxifloxacin-based regimens for drug-sensitive tuberculosis

BACKGROUND

Early-phase and preclinical studies suggest that moxifloxacin-containing regimens could allow for effective 4-month treatment of uncomplicated, smear-positive pulmonary tuberculosis.

METHODS

We conducted a randomized, double-blind, placebo-controlled, phase 3 trial to test the noninferiority of two moxifloxacin-containing regimens as compared with a control regimen. One group of patients received isoniazid, rifampin, pyrazinamide, and ethambutol for 8 weeks, followed by 18 weeks of isoniazid and rifampin (control group). In the second group, we replaced ethambutol with moxifloxacin for 17 weeks, followed by 9 weeks of placebo (isoniazid group), and in the third group, we replaced isoniazid with moxifloxacin for 17 weeks, followed by 9 weeks of placebo (ethambutol group). The primary end point was treatment failure or relapse within 18 months after randomization.

RESULTS

Of the 1931 patients who underwent randomization, in the per-protocol analysis, a favorable outcome was reported in fewer patients in the isoniazid group (85%) and the ethambutol group (80%) than in the control group (92%), for a difference favoring the control group of 6.1 percentage points (97.5% confidence interval [CI], 1.7 to 10.5) versus the isoniazid group and 11.4 percentage points (97.5% CI, 6.7 to 16.1) versus the ethambutol group. Results were consistent in the modified intention-to-treat analysis and all sensitivity analyses. The hazard ratios for the time to culture negativity in both solid and liquid mediums for the isoniazid and ethambutol groups, as compared with the control group, ranged from 1.17 to 1.25, indicating a shorter duration, with the lower bounds of the 95% confidence intervals exceeding 1.00 in all cases. There was no significant difference in the incidence of grade 3 or 4 adverse events, with events reported in 127 patients (19%) in the isoniazid group, 111 (17%) in the ethambutol group, and 123 (19%) in the control group.

CONCLUSIONS

The two moxifloxacin-containing regimens produced a more rapid initial decline in bacterial load, as compared with the control group. However, noninferiority for these regimens was not shown, which indicates that shortening treatment to 4 months was not effective in this setting. (Funded by the Global Alliance for TB Drug Development and others; REMoxTB ClinicalTrials.gov number, NCT00864383.).

Effects of Subcutaneous Pasireotide on Cardiac Repolarization in Healthy Volunteers: a Single‐Center, Phase I, Randomized, Four‐Way Crossover Study

The aim of this study was to evaluate the effects of subcutaneous pasireotide on cardiac repolarization in healthy volunteers. Healthy volunteers were randomized to one of four treatment sequences (n = 112) involving four successive treatments in different order: pasireotide 600 µg (therapeutic dose) or 1,950 µg (maximum tolerated dose) bid by subcutaneous injection (sc), placebo injection and oral moxifloxacin. Maximum ΔΔQTcI occurred 2 hours post-dose for both doses of pasireotide. Mean ΔΔQTcI was 13.2 milliseconds (90% CI: 11.4, 15.0) and 16.1 milliseconds (90% CI: 14.3, 17.9) for the 600 and 1,950 µg bid doses, respectively. Maximal placebo-subtracted change in QTcI from baseline for moxifloxacin was 11.1 (90% CI: 9.3, 12.9) milliseconds. Both pasireotide doses caused a reduction in heart rate: maximal heart rate change compared with placebo occurred at 1 hour for pasireotide 600 µg bid and at 0.5 hours for pasireotide 1,950 µg bid, with heart rate reductions of 10.4 and 14.9 bpm, respectively. At the therapeutic dose of 600 µg, pasireotide has a modest QT-prolonging effect. The relatively small increase of ∼3 milliseconds in ΔΔQTcI in the presence of a 3.25-fold increase in dose suggests a relatively flat dose–effect relationship of pasireotide on ΔΔQTcI in healthy volunteers. No safety concerns for pasireotide were identified during the study.

Gender analysis of moxifloxacin clinical trials

PURPOSE

To determine the inclusion of women and the sex-stratification of results in moxifloxacin Clinical Trials (CTs), and to establish whether these CTs considered issues that specifically affect women, such as pregnancy and use of hormonal therapies. Previous publications about women's inclusion in CTs have not specifically studied therapeutic drugs. Although this type of drug is taken by men and women at a similar rate, adverse effects occur more frequently in the latter.

METHODS

We reviewed 158 published moxifloxacin trials on humans, retrieved from MedLine and the Cochrane Library (1998-2010), to determine whether they complied with the gender recommendations published by U.S. Food and Drug Administration Guideline.

RESULTS

Of a total of 80,417 subjects included in the moxifloxacin CTs, only 33.7% were women in phase I, in contrast to phase II, where women accounted for 45%, phase III, where they represented 38.3% and phase IV, where 51.3% were women. About 40.9% (n=52) of trials were stratified by sex and 15.3% (n=13) and 9% (n=7) provided data by sex on efficacy and adverse effects, respectively. We found little information about the influence of issues that specifically affect women. Only 3 of the 59 journals that published the moxifloxacin CTs stated that authors should stratify their results by sex.

CONCLUSIONS

Women are under-represented in the published moxifloxacin trials, and this trend is more marked in phase I, as they comprise a higher proportion in the other phases. Data by sex on efficacy and adverse effects are scarce in moxifloxacin trials. These facts, together with the lack of data on women-specific issues, suggest that the therapeutic drug moxifloxacin is only a partially evidence-based medicine.

Adverse events in healthy individuals and MDR-TB contacts treated with anti-tuberculosis drugs potentially effective for preventing development of MDR-TB: a systematic review

A recent systematic review concluded that there is insufficient evidence on the effectiveness to support or reject preventive therapy for treatment of contacts of patients with multidrug resistant tuberculosis (MDR-TB). Whether preventive therapy is favorable depends both on the effectiveness and the adverse events of the drugs used. We performed a systematic review to assess adverse events in healthy individuals and MDR-TB contacts treated with anti-tuberculosis drugs potentially effective for preventing development of MDR-TB. We searched MEDLINE, EMBASE, and other databases (August 2011). Record selection, data extraction, and study quality assessment were done in duplicate. The quality of evidence was assessed using the GRADE approach. Of 6,901 identified references, 20 studies were eligible. Among the 16 studies in healthy volunteers (a total of 87 persons on either levofloxacin, moxifloxacin, ofloxacin, or rifabutin, mostly for 1 week), serious adverse events and treatment discontinuation due to adverse events were rare (<1 and <5%, respectively), but mild adverse events frequently occurred. Due to small sample sizes of the levofloxacin and ofloxacin studies an increased frequency of mild adverse events compared to placebo could not be demonstrated or excluded. For moxifloxacin the comparative results were inconsistent. In four studies describing preventive therapy of MDR-TB contacts, therapy was stopped for 58–100% of the included persons because of the occurrence of adverse events ranging from mild adverse events such as nausea and dizziness to serious events requiring treatment. The quality of the evidence was very low. Although the number of publications and quality of evidence are low, the available evidence suggests that shortly after starting treatment the occurrence of serious adverse events is rare. Mild adverse events occur more frequently and may be of importance because these may provoke treatment interruption.

In vivo comparative pharmacokinetics and pharmacodynamics of moxifloxacin and levofloxacin in human neutrophils

OBJECTIVE

Most of the newer fluoroquinolones are active against bacteria such as Streptococcus pneumoniae and Staphylococcus aureus, which are able to multiply inside polymorphonuclear leukocytes (PMNs). The aim of this study was to determine moxifloxacin and levofloxacin intracellular behaviour with their usual dosage regimen.

METHODS

We determined the pharmacokinetics of moxifloxacin and levofloxacin at steady state in the PMNs of ten healthy volunteers receiving moxifloxacin 400mg and levofloxacin 500mg as a once-daily dosing regimen for 3 days.

RESULTS

Both antibacterials showed a high level of intracellular penetration exhibiting PMNs/plasma ratios of 17.34 +/- 8.29 for moxifloxacin versus 8.15 +/- 5.23 for levofloxacin for maximum concentrations (C(max)) and 14.72 +/- 8.29 for moxifloxacin versus 8.15 +/- 5.23 for levofloxacin for the area under the plasma concentration-time curve. Estimation of the most predictive pharmacodynamic surrogate markers for concentration-dependent bactericidal antibacterials in the intracellular milieu by taking into account the susceptibility of S. pneumoniae and methicillin-susceptible S. aureus demonstrated consistently higher values with moxifloxacin than with levofloxacin, even though with both drugs the levels obtained are well above the recommended targets values. Indeed, C(max)/MIC ratios calculated in PMNs for moxifloxacin were 287.3 and 718.2 for S. pneumoniae and S. aureus, respectively, and for levofloxacin were 25.6 and 205.1, respectively.

CONCLUSION

Moxifloxacin and levofloxacin seem to be well adapted for the treatment of infections due to susceptible intracellular bacteria, and moxifloxacin provides a greater margin of safety than levofloxacin.

Assessment of the sensitivity of detecting drug-induced QTc changes using subject-specific rate correction

AIMS

To quantify the sensitivity of QT heart-rate correction methods for detecting drug-induced QTc changes in thorough QT studies.

METHODS

Twenty-four-hour Holter ECGs were analyzed in 66 normal subjects during placebo and moxifloxacin delivery (single oral dose). QT and RR time series were extracted. Three QTc computation methods were used: (1) Fridericia's formula, (2) Fridericia's formula with hysteresis reduction, and (3) a subject-specific approach with transfer function-based hysteresis reduction and three-parameter non-linear fitting of the QT-RR relation. QTc distributions after placebo and moxifloxacin delivery were compared in sliding time windows using receiver operating characteristic (ROC) curves. The area under the ROC curve (AUC) served as a measure to quantify the ability of each method to detect moxifloxacin-induced QTc prolongation.

RESULTS

Moxifloxacin prolonged the QTc by 10.6 ± 6.6 ms at peak effect. The AUC was significantly larger after hysteresis reduction (0.87 ± 0.13 vs. 0.82 ± 0.12, p<0.01) at peak effect, indicating a better discriminating capability. Subject-specific correction further increased the AUC to 0.91 ± 0.11 (p<0.01 vs. Fridericia with hysteresis reduction). The performance of the subject-specific approach was the consequence of a substantially lower intra-subject QTc standard deviation (5.7 ± 1.1 ms vs. 8.8 ± 1.2 ms for Fridericia).

CONCLUSION

The ROC curve provides a tool for quantitative comparison of QT heart rate correction methods in the context of detecting drug-induced QTc prolongation. Results support a broader use of subject-specific QT correction.

Moxifloxacin in the treatment of skin and skin structure infections

Moxifloxacin is a recent addition to the fluoroquinolone class, differing from ciprofloxacin and other older agents in having much better in vitro activity against Gram-positive aerobes while retaining potent activity against Gram-negative aerobes. It is also active against the pathogens of human and animal bite wounds and those species of atypical mycobacteria associated with dermatologic infections. Its activity against anaerobes is quite variable. Moxifloxacin penetrates well into inflammatory blister fluid and muscle and subcutaneous adipose tissues. Moxifloxacin should thus be a reasonable option for the treatment of skin and skin structure infections (SSSIs). In 3 randomized controlled trials (RCTs), oral moxifloxacin was as effective as cephalexin in the treatment of uncomplicated SSSIs in adults while in 2 RCTs, intravenous/oral moxifloxacin was as effective as intravenous/oral β-lactam/β-lactamase inhibitor therapy in the treatment of complicated SSSIs in adults. Moxifloxacin does not inhibit cytochrome P450 enzymes and thus interact with warfarin or methylxanthines. However, multivalent cations can reduce its oral bioavailability substantially. Dosage adjustment is not required in the presence of renal or hepatic impairment. The clinical relevance of its electrophysiologic effects (QT_c prolongation) remains unresolved.

Thorough QT study of the effects of vildagliptin, a dipeptidyl peptidase IV inhibitor, on cardiac repolarization and conduction in healthy volunteers

OBJECTIVE

This randomized, double-blind study evaluated the effects of vildagliptin, a dipeptidyl peptidase IV inhibitor for treating type 2 diabetes, on cardiac repolarization and conduction.

METHODS

Healthy volunteers (n = 101) were randomized (1:1:1:1 ratio) to vildagliptin 100 or 400 mg, moxifloxacin 400 mg (active control), or placebo once daily for 5 days. Electrocardiograms were recorded at baseline and day 5 for 24 hours post-dose. Placebo-adjusted mean change from baseline in QT interval, heart-rate-corrected QT intervals by Fridericia's (QTcF) or Bazett's (QTcB) formula, and PR and QRS intervals were compared at each time-point (time-matched analysis) and for values averaged across the dosing period (time-averaged analysis).

RESULTS

For time-matched analysis, mean changes in QTcF with vildagliptin were below predefined limits for QTc prolongation (mean increase <5 ms; upper 90% confidence interval [CI] < 10 ms), except for vildagliptin 100 mg at 1 and 8 hours post-dose (upper 90% CI > 10 ms). With moxifloxacin, significant QTcF prolongation occurred at most time-points, demonstrating assay sensitivity. No vildagliptin- or placebo-treated volunteer had QTcF > 450 ms. Incidences of QTcF increases ≥30 ms with vildagliptin (100 and 400 mg) and placebo were similar (4-8%) and were much lower than with moxifloxacin (39%). No QTcF increase ≥60 ms was observed with vildagliptin or placebo (versus one with moxifloxacin). Time-averaged, time-matched, and categorical analyses of QT/QTcF/QTcB showed similar results. Drug exposure analysis showed no correlation between vildagliptin plasma levels and QTc changes. Vildagliptin had no effect on PR or QRS intervals. Although this study, completed before publication of current ICH E14 guidelines, was underpowered for time-matched analysis, the results are consistent with lack of effect of vildagliptin on QTc.

CONCLUSION

Vildagliptin did not prolong QT interval or affect cardiac conduction at the highest daily therapeutic dose or a fourfold higher dose.

Use of an in vitro pharmacodynamic model to derive a moxifloxacin regimen that optimizes kill of Yersinia pestis and prevents emergence of resistance

Yersinia pestis, the causative agent of bubonic, septicemic, and pneumonic plague, is classified as a CDC category A bioterrorism pathogen. Streptomycin and doxycycline are the "gold standards" for the treatment of plague. However, streptomycin is not available in many countries, and Y. pestis isolates resistant to streptomycin and doxycycline occur naturally and have been generated in laboratories. Moxifloxacin is a fluoroquinolone antibiotic that demonstrates potent activity against Y. pestis in in vitro and animal infection models. However, the dose and frequency of administration of moxifloxacin that would be predicted to optimize treatment efficacy in humans while preventing the emergence of resistance are unknown. Therefore, dose range and dose fractionation studies for moxifloxacin were conducted for Y. pestis in an in vitro pharmacodynamic model in which the half-lives of moxifloxacin in human serum were simulated so as to identify the lowest drug exposure and the schedule of administration that are linked with killing of Y. pestis and with the suppression of resistance. In the dose range studies, simulated moxifloxacin regimens of ≥175 mg/day killed drug-susceptible bacteria without resistance amplification. Dose fractionation studies demonstrated that the AUC (area under the concentration-time curve)/MIC ratio predicted kill of drug-susceptible Y. pestis, while the C(max) (maximum concentration of the drug in serum)/MIC ratio was linked to resistance prevention. Monte Carlo simulations predicted that moxifloxacin at 400 mg/day would successfully treat human infection due to Y. pestis in 99.8% of subjects and would prevent resistance amplification. We conclude that in an in vitro pharmacodynamic model, the clinically prescribed moxifloxacin regimen of 400 mg/day is predicted to be highly effective for the treatment of Y. pestis infections in humans. Studies of moxifloxacin in animal models of plague are warranted.

Levofloxacin can be used effectively as a positive control in thorough QT/QTc studies in healthy volunteers

AIMS

To characterize the effects of levofloxacin on QT interval in healthy subjects and the most appropriate oral positive control treatments for International Conference on Harmonization (ICH) E14 QT/QTc studies.

METHODS

Healthy subjects received a single dose of levofloxacin (1000 or 1500 mg), moxifloxacin (400 mg) or placebo in a four-period crossover design. Digital 12-lead ECGs were recorded in triplicate. Measurement of QT interval was performed automatically with subsequent manual onscreen over-reading using electronic callipers. Blood samples were taken for determination of levofloxacin and moxifloxacin concentrations.

RESULTS

Mean QTcI (QT interval corrected for heart rate using a correction factor that is applicable to each individual) was prolonged in subjects receiving moxifloxacin 400 mg compared with placebo. The largest time-matched difference in QTcI for moxifloxacin compared with placebo was observed to be 13.19 ms (95% confidence interval 11.21, 15.17) at 3.5 h post dose. Prolonged mean QTcI was also observed in subjects receiving levofloxacin 1000 mg and 1500 mg compared with placebo. The largest time-matched difference in QTcI compared with placebo was observed at 3.5 h post dose for both 1000 mg and 1500 mg of levofloxacin [mean (95%) 4.42 ms (2.44, 6.39) in 1000 mg and 7.44 ms (5.47, 9.42) in 1500 mg]. A small increase in heart rate was observed with levofloxacin during the course of the study. However, moxifloxacin showed a greater increase compared with levofloxacin.

CONCLUSIONS

Both levofloxacin and moxifloxacin can fulfil the criteria for a positive comparator. The ICH E14 guidelines recommend a threshold of around 5 ms for a positive QT/QTc study. The largest time-matched difference in QTc for levofloxacin suggests the potential for use in more rigorous QT/QTc studies. This study has demonstrated the utility of levofloxacin on the assay in measuring mean QTc changes around 5 ms.

Moxifloxacin pharmacokinetics/pharmacodynamics and optimal dose and susceptibility breakpoint identification for treatment of disseminated Mycobacterium avium infection

Organisms of the Mycobacterium avium-intracellulare complex (MAC) have been demonstrated to be susceptible to moxifloxacin. However, clinical data on how to utilize moxifloxacin to treat disseminated MAC are scanty. In addition, there have been no moxifloxacin pharmacokinetic-pharmacodynamic (PK/PD) studies performed for MAC infection. We utilized an in vitro PK/PD model of intracellular MAC to study moxifloxacin PK/PD for disseminated disease. Moxifloxacin doses, based on a serum half-life of 12 h, were administered, and the 0- to 24-h area under the concentration-time curve (AUC(0-24)) to MIC ratios associated with 1.0 log(10) CFU/ml per week kill and 90% of maximal kill (EC(90)) were identified. The AUC(0-24)/MIC ratio associated with 1.0 log(10) CFU/ml kill was 17.12, and that with EC(90) was 391.56 (r(2) = 0.97). Next, the moxifloxacin MIC distribution in 102 clinical isolates of MAC was identified. The median MIC was 1 to 2 mg/liter. Monte Carlo simulations of 10,000 patients with disseminated MAC were performed to determine the probability that daily moxifloxacin doses of 400 and 800 mg/day would achieve or exceed 1.0 log(10) CFU/ml per week kill or EC(90). Doses of 400 and 800 mg/day achieved the AUC(0-24)/MIC ratio of 17.12 in 64% and 92% of patients, respectively. The critical concentration of moxifloxacin against MAC was identified as 0.25 mg/liter in Middlebrook media. The proposed susceptibility breakpoint means that a larger proportion of clinical isolates is resistant to moxifloxacin prior to therapy. For patients infected with susceptible isolates, however, 800 mg a day should be examined for safety and efficacy for disseminated M. avium disease.

Effect of levetiracetam on cardiac repolarization in healthy subjects: a single-dose, randomized, placebo- and active-controlled, four-way crossover study

BACKGROUND

Nonantiarrhythmic drugs may have the potential to prolong the QT interval, leading to potentially fatal ventricular tachycardias, including torsades de pointes.

OBJECTIVE

This study evaluated the potential of the newer-generation, multiple-action antiepileptic drug levetiracetam, which binds to the synaptic vesicle protein SV2A, to affect cardiac repolarization, as detected by prolongation of the QT/corrected QT (QTc) interval.

METHODS

This was a single-dose, randomized, placebo- and active-controlled, 4-way crossover study in healthy subjects. Subjects were randomly allocated to 1 of 4 different administration sequences. Each sequence included 3 double-blind treatments (levetirace-tam 1000 mg, levetiracetam 5000 mg, and placebo) and 1 open-label treatment (moxifloxacin 400 mg). Triplicate electrocardiograms (ECGs) were obtained at baseline and at various time points over 24 hours after each treatment using continuous Holter monitoring. ECGs were read centrally in a blinded manner. Blood samples for the determination of plasma concentrations of levetiracetam and moxifloxacin were collected before dosing and at 0.5, 1, 1.5, 2, 4, 6, 12, and 24 hours after dosing, within 5 minutes after the ECG recordings. The QT interval was corrected for heart rate using a sex- and study-specific correction (QTc(ss)) as the primary outcome measure and Fridericia's correction (QTc(F))as a secondary outcome measure. The primary analysis was performed on the time-matched, baseline-subtracted QTc(ss) (DeltaQTc(ss)). The maximum DeltaQTc(ss) difference between each active treatment and placebo (DeltaDeltaTc(ss)) was derived from a mixed-effect analysis of variance. Clinical laboratory tests, standard 12-lead ECGs, and vital signs were monitored at regular intervals. Spontaneously reported adverse events were recorded throughout the study.

RESULTS

Fifty-two healthy, nonsmoking subjects (26 men, 26 women; 37 white, 9 black, 3 Hispanic, and 3 Asian/Pacific Islander) with a mean (SD) age of 28.4 (7.5) years (range, 18-45 years) and a mean weight of 71.5 (12.6) kg (range, 49-103 kg) participated in the study. Levetiracetam did not significantly prolong the QTc(ss). The upper bound of the 1-sided 95% CI for the maximum DeltaDeltaTc(ss) was 8.0 milliseconds for levetiracetam 1000 mg and 8.1 milliseconds for levetiracetam 5000 mg, with mean estimates of 4.0 and 4.1 milliseconds, respectively; similar results were obtained for the maximum DeltaDeltaQTc(F). Moxifloxacin significantly prolonged the QTc(ss), with a lower bound of the 1-sided 95% CI for the maximum DeltaDeltaQTc(ss) of 3.7 milliseconds and a mean estimate of 7.7 milliseconds. There was no statistically significant relationship between measured DeltaQTc(ss) and the levetiracetam plasma concentration, whereas a significant linear relationship was observed between measured DeltaQTc(ss) and the moxifloxacin plasma concentration (slope estimate: 4.4 milliseconds/[microg/mL]); 95% CI, 3.2-5.7; P < 0.001). No unexpected safety concerns arose based on reported adverse events, clinical laboratory evaluations, physical examinations, vital signs, or ECG monitoring during the course of the study.

CONCLUSION

This randomized, placebo- and active-controlled study in healthy adult subjects found no clinically relevant changes in the QTc interval after a single levetiracetam dose of 1000 or 5000 mg.

Tissue penetration of moxifloxacin into human gallbladder wall in patients with biliary tract infections

OBJECTIVES

Moxifloxacin, the newest fourth-generation fluoroquinolone, has a broad spectrum of antibacterial activity covering both Gram-positive and Gram-negative aerobic and anaerobic bacteria and is therefore very well suited for the treatment of biliary tract infections. The present study aimed to determine the penetration of moxifloxacin into gallbladder tissue to evaluate its antibiotic potential in this indication.

PATIENTS AND METHODS

Hospitalized patients with acute cholecystitis received a single, 1 h infusion of 400 mg of moxifloxacin before cholecystectomy. Serum and gallbladder wall tissue samples were collected during surgery, and the moxifloxacin concentrations were measured by HPLC.

RESULTS

Sixteen patients (eight men and eight women) were included between January 2007 and April 2008. The time between start of infusion and gallbladder removal ranged from 50 min to 21 h 10 min. The serum concentration at the time of cholecystectomy was between 0.39 and 4.37 mg/L, and the tissue concentration between 1.73 and 17.08 mg/kg. The tissue-to-serum concentration ratio ranged from 1.72 to 6.33.

CONCLUSIONS

The results show that moxifloxacin penetrates well into gallbladder tissue and is therefore a therapeutic option for biliary tract infection. The highest concentrations in serum and gallbladder tissue were measured shortly after the end of a 1 h infusion. As perioperative prophylaxis, moxifloxacin should therefore be administered 30-60 min before the first surgical incision.

Pharmacokinetics of Moxifloxacin in Patients Undergoing Continuous Ambulatory Peritoneal Dialysis

Objective

To investigate the effect of continuous ambulatory peritoneal dialysis (CAPD) on plasma and peritoneal fluid concentration and pharmacokinetics of moxifloxacin after administration of one 400 mg dose orally to end-stage renal failure patients undergoing CAPD.

Patients and Methods

Blood and peritoneal samples were collected from 8 patients at standard time intervals and concentrations of moxifloxacin were estimated by HPLC analysis with fluorometric and ultraviolet detection. Pharmacokinetic parameters were estimated using standard noncompartmental methods.

Results

Median maximum plasma moxifloxacin concentration was 5.86 mg/L at a median time of 1.25 hours. In serum, median area under the concentration–time curve (AUC0→inf) was 157.95 ± 100.34 mg·hour/L, median t½ 25.00 hours, median clearance 2.54 L/hour, and median distribution volume 94.90 L. Median peritoneal fluid-to-plasma ratio of moxifloxacin ranged between 0.84 and 1.00, denoting adequate penetration and lack of considerable moxifloxacin removal during CAPD. Maximum moxifloxacin concentration/minimum inhibitory concentration (MIC) and AUC0→24/MIC ratios were above the cutoff points that indicate clinical success.

Conclusion

A single 400 mg oral dose of moxifloxacin is safe, presents rapid peritoneal fluid penetration, has similar plasma and peritoneal fluid pharmacokinetics, and should therefore be efficacious in the treatment of CAPD-induced peritonitis.

Impact of spore biology on the rate of kill and suppression of resistance in Bacillus anthracis

Bacillus anthracis is complex because of its spore form. The spore is invulnerable to antibiotic action. It also has an impact on the emergence of resistance. We employed the hollow-fiber infection model to study the impacts of different doses and schedules of moxifloxacin on the total-organism population, the spore population, and the subpopulations of vegetative- and spore-phase organisms that were resistant to moxifloxacin. We then generated a mathematical model of the impact of moxifloxacin, administered by continuous infusion or once daily, on vegetative- and spore-phase organisms. The ratio of the rate constant for vegetative-phase cells going to spore phase (K(vs)) to the rate constant for spore-phase cells going to vegetative phase (K(sv)) determines the rate of organism clearance. The continuous-infusion drug profile is more easily sensed as a threat; the K(vs)/K(sv) ratio increases at lower drug exposures (possibly related to quorum sensing). This movement to spore phase protects the organism but makes the emergence of resistance less likely. Suppression of resistance requires a higher level of drug exposure with once-daily administration than with a continuous infusion, a difference that is related to vegetative-to-spore (and back) transitioning. Spore biology has a major impact on drug therapy and resistance suppression. These findings explain why all drugs of different classes have approximately the same rate of organism clearance for Bacillus anthracis.

Substitution of moxifloxacin for isoniazid during intensive phase treatment of pulmonary tuberculosis

RATIONALE

Moxifloxacin has potent activity against Mycobacterium tuberculosis in vitro and in a mouse model of antituberculosis (TB) chemotherapy, but data regarding its activity in humans are limited.

OBJECTIVES

Our objective was to compare the antimicrobial activity and safety of moxifloxacin versus isoniazid during the first 8 weeks of combination therapy for pulmonary TB.

METHODS

Adults with sputum smear-positive pulmonary TB were randomly assigned to receive either moxifloxacin 400 mg plus isoniazid placebo, or isoniazid 300 mg plus moxifloxacin placebo, administered 5 days/week for 8 weeks, in addition to rifampin, pyrazinamide, and ethambutol. All doses were directly observed. Sputum was collected for culture every 2 weeks. The primary outcome was negative sputum culture at completion of 8 weeks of treatment.

MEASUREMENTS AND MAIN RESULTS

Of 433 participants enrolled, 328 were eligible for the primary efficacy analysis. Of these, 35 (11%) were HIV positive, 248 (76%) had cavitation on baseline chest radiograph, and 213 (65%) were enrolled at African sites. Negative cultures at Week 8 were observed in 90/164 (54.9%) participants in the isoniazid arm, and 99/164 (60.4%) in the moxifloxacin arm (P = 0.37). In multivariate analysis, cavitation and enrollment at an African site were associated with lower likelihood of Week-8 culture negativity. The proportion of participants who discontinued assigned treatment was 31/214 (14.5%) for the moxifloxacin group versus 22/205 (10.7%) for the isoniazid group (RR, 1.35; 95% CI, 0.81, 2.25).

CONCLUSIONS

Substitution of moxifloxacin for isoniazid resulted in a small but statistically nonsignificant increase in Week-8 culture negativity.

Respiratory fluoroquinolones for the treatment of community-acquired pneumonia: a meta-analysis of randomized controlled trials

BACKGROUND

We investigated whether the use of respiratory fluoroquinolones was associated with better clinical outcomes compared with the use of macrolides and beta- lactams among adults with pneumonia.

METHODS

We searched PubMed, Current Contents, Scopus, EMBASE, ClinicalTrials.gov and Cochrane with no language restrictions. Two reviewers independently extracted data from published trials that compared fluoroquinolones (levofloxacin, moxifloxacin, gemifloxacin) with macrolides or beta-lactams or both. A meta-analysis was performed with the clinical outcomes of mortality, treatment success and adverse outcomes.

RESULTS

We included 23 trials in our meta-analysis. There was no difference in mortality among patients who received fluoroquinolones or the comparator antibiotics (OR 0.85, 95% CI 0.65-1.12). Pneumonia resolved in more patients who received fluoroquinolones compared with the comparator antibiotics for the included outcomes in the intention-to-treat population (OR 1.17, 95% CI 1.00-1.36), clinically evaluable population (OR 1.26, 95% CI 1.06-1.50) and the microbiologically assessed population (OR 1.67, 95% CI 1.28-2.20). Fluoroquinolones were more effective than a combination of beta-lactam and macrolide (OR 1.39, 95% CI 1.02-1.90). They were also more effective for patients with severe pneumonia (OR 1.84, 95% CI 1.02-3.29), those who required admission to hospital (OR = 1.30, 95% CI 1.04-1.61) and those who required intravenous therapy (OR = 1.44, 15% CI 1.13-1.85). Fluoroquinolones were more effective than beta-lactam and macrolide in open-label trials (OR = 1.35, 95% CI 1.08-1.69) but not in blinded randomized controlled trials (OR = 1.13, 95% CI 0.85-1.50).

INTERPRETATION

Fluoroquinolones were associated with higher success of treatment for severe forms of pneumonia; however, a benefit in mortality was not evident. A randomized controlled trial that includes patients with severe pneumonia with or without bacteremia is needed.