Threat of respiratory syncytial virus infection knocking the door: a proposed potential drug candidate through molecular dynamics simulations, a future alternative

The discovery of antiviral approaches to prevent or cure respiratory syncytial virus (RSV) infections is critical, particularly because RSV is one of the most common causes of infant respiratory problems. There is currently no approved vaccination available to treat RSV infections. FDA has approved the drug ribavirin, but it is not sufficient to treat RSV. This work aimed to find and study in silico anti-RSV drugs that target matrix protein and nucleoprotein. In this study, we have identified five drug candidates that had better binding energies than ribavirin. Garenoxacin appeared as top lead compounds between them. AutoDock Vina was used to execute molecular docking of a library of chosen chemicals. The high-score compound was then confirmed using the Maestro 12.3 module's molecular dynamics simulation and the binding energies derived using Prime/Molecular Mechanics Generalized Born Surface Area (Prime/MM-GBSA). Comparative molecular dynamics simulations revealed that garenoxacin has better stability and high residue contacts with high binding affinity than ribavirin. This study showed garenoxacin could prevent RSV infection better than ribavirin. In pursuing a more effective RSV control drug, additional research into these chemicals in vitro and in vivo is essential.

Effectiveness of antibacterial agents against cell-invading bacteria such as Streptococcus pyogenes and Haemophilus influenzae

BACKGROUND

Recurrent tonsillitis is one of the most common otolaryngological disorders caused by cell-invading bacteria, such as Streptococcus pyogenes (S. pyogenes) and Haemophilus influenzae. The aim of this study was to investigate the effect of antibacterial agents against cell-invading bacteria.

METHODS

The intracellular invasion of Detroit 562 cells by five strains of nontypeable Haemophilus influenzae (NTHi) and four strains of S. pyogenes was investigated. The antibacterial agents used were garenoxacin (GRNX), clarithromycin (CAM), amoxicillin (AMPC), cefditoren pivoxil (CDTR-PI), and levofloxacin (LVFX).

RESULTS

Both NTHi and S. pyogenes fully invaded Detroit 562 cells in 6 h and were less sensitive to CAM. GRNX, CAM, and LVFX were effective against bacteria invading the cells, but AMPC and CDTR-PI were not effective. GRNX was the most effective.

CONCLUSION

GRNX was the most effective agent against bacteria invading cells.

The clinical efficacy of garenoxacin for male non-gonococcal urethritis

Sitafloxacin (STFX) is an alternative treatment against azithromycin-resistant Mycoplasma genitalium (MG), whereas STFX-resistant MG have appeared recently. Therefore, another antimicrobial regimen for non-chlamydial non-gonococcal urethritis (NGU) is required. Garenoxacin (GRNX) is a fluoroquinolone against respiratory infections, not against urethritis in Japan, but its in-vitro antimicrobial activity against MG is known as similar to or higher than that of moxifloxacin. To clarify the efficiency of GRNX against MG, we examined the clinical efficacy of GRNX for NGU. Seventy-nine male patients with NGU were enrolled and treated with GRNX once daily for 7 days. For assessing microbiological and clinical efficacies, the bacteria including Chlamydia trachomatis (CT), MG, Mycoplasma hominis (MH), Ureaplasma urealyticum (UU) and Ureaplasma parvum (UP) were detected by means of nucleic acid amplification tests before- and after-treatment. After excluded 3 patients, seventy-six patients were evaluated: the median age; 31 (20-61) years, vaginal infection (66%); the most common infectious route and commercial sex worker (43%); the most common source. There were 50 bacteria-positive NGU cases, including 10 multiple bacterial infections. Clinical cure rate was 85.7% (36/42). Detection frequency of each bacterium was similar to the previous reported. The eradication rates of CT, MG, MH, UU and UP were 96.1%, 71.4%, 100%, 85.7% and 100%, respectively. These results indicate that GRNX has the excellent efficacies for NGU except those of MG. Further study of drug-resistant MG urethritis; for instance, studies on the clinical effectiveness of long-term such as 2-week medication of GRNX or the efficacy of alternative treatment regimens are necessary.

Beneficial Effect of Early Intervention with Garenoxacin for Bacterial Infection-Induced Acute Exacerbation of Bronchial Asthma and Chronic Obstructive Pulmonary Disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) and asthma have similar clinical features and are both exacerbated by airway infection.

OBJECTIVE

To determine whether garenoxacin mesylate hydrate (GRNX) added to the standard care for bacterial infection-induced acute exacerbation of asthma or COPD in adults has clinical benefits.

METHOD

This single-arm clinical trial was conducted from January 2015 to March 2016. Adults with a history of asthma or COPD for more than 12 months were recruited within 48 h of presentation with fever and acute deterioration of asthma or COPD requiring additional intervention. Participants were administered 400 mg GRNX daily for 7 days without additional systemic corticosteroids or other antibiotics. The primary outcome was efficacy of GRNX based on clinical symptoms and blood test results after 7 days of treatment. Secondary outcomes were: (1) comparison of the blood test results, radiograph findings, and bacterial culture surveillance before and after treatment; (2) effectiveness of GRNX after 3 days of administration; (3) analyzation of patient symptoms based on patient diary; and (4) continued effectiveness of GRNX on 14th day after the treatment (visit 3).

RESULTS

The study included 44 febrile patients (34 asthma and 10 COPD). Frequently isolated bacteria included Moraxella catarrhalis (n = 6) and Klebsiella pneumoniae (n = 4). On visit 2, 40 patients responded, and no severe adverse events were observed. All secondary outcomes showed favorable results.

CONCLUSION

GRNX effectively treated asthma and COPD patients with acute bacterial infection without severe adverse events. Further research with a larger study population is needed.

Effectiveness and safety of the pre-prescription of garenoxacin in comparison to moxifloxacin for low-risk febrile neutropenia in breast cancer patients undergoing adjuvant and neoadjuvant chemotherapy

PURPOSE

The purpose of this study was to compare the efficacy of the pre-prescription of garenoxacin mesylate hydrate (GRNX) with that of moxifloxacin hydrochloride (MFLX) in the management of breast cancer patients with low-risk febrile neutropenia.

METHODS

Data from female patients who had been instructed to take previously prescribed oral GRNX or MFLX for 3 days during adjuvant and neoadjuvant chemotherapy if their body temperature exceeded 38 °C were analyzed. This study compared the effectiveness between these fluoroquinolones using a propensity score matching analysis.

RESULTS

The 330 patients received 1192 administrations of chemotherapy between May 2007 and April 2014 and 136 (41.2%) patients had a total of 212 (17.8%) febrile episodes. The frequencies of febrile episodes were 19.5% (113/579) and 16.2% (99/613) in the GRNX and MFLX groups, respectively. After propensity score matching, 384 episodes were matched in each group. Febrile events occurred in 80 and 56 cases in the GRNX and MFLX groups, respectively. Treatment success was identified in 80.0% (64/80) of cases in the GRNX group and 64.3% (36/56) of cases in the MFLX group (P = 0.0494). Additionally, the therapeutic use of granulocyte-colony stimulating factor was 6.3% (5/80) of cases in the GRNX group and 17.9% (10/56) of cases in the MFLX group (P = 0.0498). There were few differences in the frequency of adverse effects between the two groups.

CONCLUSIONS

These results indicate that the pre-prescription of GRNX may be a more effective option for the management of low-risk febrile neutropenia during adjuvant and neoadjuvant chemotherapy for breast cancer.

Proposed Pharmacokinetic-Pharmacodynamic Breakpoint of Garenoxacin and Other Quinolones

The pharmacokinetic-pharmacodynamic (PK-PD) breakpoints (BPs) of garenoxacin (GRNX) and other oral quinolones were calculated using Monte Carlo simulation (MCS) based on the distribution of changes in their plasma concentrations. PK-PD BPs of 400 mg once a day (QD) of GRNX for the free area under the curve/minimum inhibitory concentration (fAUC/MIC) for 30 strains of Streptococcus pneumoniae and 100 strains of gram-negative bacteria (G [－]) were 0.5 and 0.125 μg/mL, respectively. PK-PD BPs of other quinolones for S. pneumoniae/G (－) were 1/0.25 μg/mL for levofloxacin (LVFX) 500 mg QD, 0.5/0.125 μg/mL for moxifloxacin (MFLX) 400 mg QD, 0.0625/0.0156 μg/mL for sitafloxacin (STFX) 50 mg twice a day (BID) (100 mg QD), and 0.125/0.0313 μg/mL for STFX 100 mg BID. We also investigated the hypothetical probability of target attainments (PTAs) of fAUC/MIC for community-acquired pneumonia (CAP) using MCS, in consideration of the isolation frequencies of the three main causative pathogens of CAP: S. pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. For hypothetical CAP in adults, PTA of fAUC/MIC was 100% with GRNX and MFLX, 96%-97% with STFX at 100 mg BID, 45%-46% with LVFX, and 53%-58% with STFX at 100 mg QD and 50 mg BID. Based on the PK-PD BP, GRNX showed higher fAUC/MIC than the other quinolones tested against the three main pathogens of respiratory infections.

Comparison of levofloxacin and garenoxacin for antibacterial prophylaxis during neutropenia

Levofloxacin (LVFX) is widely used for antibacterial prophylaxis during neutropenia. Garenoxacin (GRNX), which has been investigated in Japan, has stronger antibacterial activity than LVFX against gram-positive bacteria; however, no studies have compared the effectiveness of LVFX and GRNX. We retrospectively analyzed 42 patients with acute leukemia and 32 patients who underwent hematopoietic cell transplantation. Thirty-one patients before September 2009 received GRNX, and subsequent 43 patients received LVFX. We compared the cumulative incidences of positive blood and stool cultures. There was no significant difference in the incidence of bacteremia between the GRNX and LVFX groups. However, while gram-negative bacteria were detected in 80% of the patients with bacteremia in the GRNX group, they were detected in only 33% of the patients with bacteremia in the LVFX group. Patients in the GRNX group more frequently experienced positive stool cultures than those in the LVFX group, and this was confirmed by a multivariate analysis. Gram-negative bacteria accounted for 100 and 67% of the stool culture results in the GRNX and LVFX groups, respectively. While both fluoroquinolones may be appropriate antibacterial prophylactic agents for neutropenia patients with hematological malignancies, vigilance for gram-negative bacterial infections should be exercised when GRNX is used as prophylaxis.

Thoracic empyema caused by Campylobacter rectus

We report a case of thoracic empyema caused by Campylobacter rectus, an organism considered as a periodontal pathogen but rarely recovered from extraoral specimens. The patient fully recovered through drainage of purulent pleural fluid and administration of antibiotics. The present case illustrates that C. rectus can be a cause of not only periodontal disease but also pulmonary infection.

Therapeutic effects of garenoxacin in murine experimental secondary pneumonia by Streptococcus pneumoniae after influenza virus infection

In a pneumococcal pneumonia murine model following influenza virus infection, garenoxacin was more effective than other fluoroquinolones and demonstrated high levels of bacterial eradication in the lung, low mortality, and potent histopathological improvements. Garenoxacin could potentially be used for the treatment of secondary pneumococcal pneumonia following influenza.

Torsades de pointes induced by garenoxacin in association with pacing failure in an elderly woman with VDD pacemaker

An 86-year-old woman was admitted to the hospital for syncope and convulsion 4 days after starting antibiotic therapy for pneumonia with oral garenoxacin 400 mg/day. She had a VDD pacemaker for complete atrioventricular (AV) block. Her electrocardiogram showed marked QT prolongation and during pacemaker interrogation pacing failure probably due to battery depletion induced torsades de pointes. After cessation of garenoxacin, QTc returned to normal range subsequently and a new pacemaker was implanted. In patients with risks of QT prolongation, garenoxacin should be used cautiously with QT interval monitoring.