Trovafloxacin

In Silico Identification and In Vitro Validation of Repurposed Compounds Targeting the RSV Polymerase

Respiratory Syncytial Virus (RSV) is the top cause of infant hospitalization globally, with no effective treatments available. Researchers have sought small molecules to target the RNA-dependent RNA Polymerase (RdRP) of RSV, which is essential for replication and transcription. Based on the cryo-EM structure of the RSV polymerase, in silico computational analysis including molecular docking and the protein-ligand simulation of a database, including 6554 molecules, is currently undergoing phases 1-4 of clinical trials and has resulted in the top ten repurposed compound candidates against the RSV polymerase, including Micafungin, Totrombopag, and Verubecestat. We performed the same procedure to evaluate 18 small molecules from previous studies and chose the top four compounds for comparison. Among the top identified repurposed compounds, Micafungin, an antifungal medication, showed significant inhibition and binding affinity improvements over current inhibitors such as ALS-8112 and Ribavirin. We also validated Micafungin's inhibition of the RSV RdRP using an in vitro transcription assay. These findings contribute to RSV drug development and hold promise for broad-spectrum antivirals targeting the non-segmented negative-sense (NNS) RNA viral polymerases, including those of rabies (RABV) and Ebola (EBOV).

Biological Effects of Quinolones: A Family of Broad-Spectrum Antimicrobial Agents

Broad antibacterial spectrum, high oral bioavailability and excellent tissue penetration combined with safety and few, yet rare, unwanted effects, have made the quinolones class of antimicrobials one of the most used in inpatients and outpatients. Initially discovered during the search for improved chloroquine-derivative molecules with increased anti-malarial activity, today the quinolones, intended as antimicrobials, comprehend four generations that progressively have been extending antimicrobial spectrum and clinical use. The quinolone class of antimicrobials exerts its antimicrobial actions through inhibiting DNA gyrase and Topoisomerase IV that in turn inhibits synthesis of DNA and RNA. Good distribution through different tissues and organs to treat Gram-positive and Gram-negative bacteria have made quinolones a good choice to treat disease in both humans and animals. The extensive use of quinolones, in both human health and in the veterinary field, has induced a rise of resistance and menace with leaving the quinolones family ineffective to treat infections. This review revises the evolution of quinolones structures, biological activity, and the clinical importance of this evolving family. Next, updated information regarding the mechanism of antimicrobial activity is revised. The veterinary use of quinolones in animal productions is also considered for its environmental role in spreading resistance. Finally, considerations for the use of quinolones in human and veterinary medicine are discussed.

Systemic quinolone antibiotics in children: a review of the use and safety

Historically, healthcare providers have reluctantly used systemic quinolone antibiotics to treat infections in children when they have been used at all. Concerns regarding the oral or parenteral use of quinolones in children rose from research observations demonstrating cartilage and joint toxicity in juvenile animal models following the administration of this class of antibiotics to immature animals. A voluntary moratorium on the use of quinolone and fluoroquinolone antibiotics in children resulted in restricting their use to treat in infections in specific settings such as immunocompromised states due to chemotherapy, pseudomonas infections in cystic fibrosis patients, complicated urinary tract infections, and quinolone sensitive infectious disease where parenteral antibiotic administration is not available and quinolones were the only effective therapy. This article aims to review retrospective and prospective safety and efficacy data to provide a comprehensive summary of the systemic use of this class of antibiotics in children.

Is more than one quinolone needed in clinical practice?

OBJECTIVE

To review clinical information on fluoroquinolone antimicrobials to distinguish between these agents and help define their place in clinical practice.

DATA SOURCES

Primary and review articles on fluoroquinolones available commercially in the US as of August 2000 were identified through MEDLINE (from 1993-August 2000) and secondary sources.

STUDY SELECTION AND DATA EXTRACTION

All pertinent, published, clinical trials for levofloxacin, moxifloxacin, and gatifloxacin were included. Minimal data were included for quinolones with restricted or limited uses, including trovafloxacin, sparfloxacin, enoxacin, and lomefloxacin. Due to the quantity of data on ciprofloxacin, only more recent or pivotal trials or articles summarizing data on specific infections were included. Relevant information was included if it was believed to assist in differentiating between the fluoroquinolones for infections for which these agents would most commonly be considered.

DATA SYNTHESIS

Fluoroquinolones are a potent class of intravenous and oral broad-spectrum antimicrobial agents used for treating a wide range of community-acquired and nosocomial infections. More than 10 quinolones have been approved for use; although some of these have been withdrawn from the market, numerous others are under investigation. It has become increasingly important to be able to differentiate between these agents.

CONCLUSIONS

Differences in safety, antimicrobial spectrum of activity, and resistance development support the selective use of various fluoroquinolones in differing clinical situations.

Evaluation of human intestinal absorption data and subsequent derivation of a quantitative structure–activity relationship (QSAR) with the Abraham descriptors

The human intestinal absorption of 241 drugs was evaluated. Three main methods were used to determine the human intestinal absorption: bioavailability, percentage of urinary excretion of drug-related material following oral administration, and the ratio of cumulative urinary excretion of drug-related material following oral and intravenous administration. The general solvation equation developed by Abraham's group was used to model the human intestinal absorption data of 169 drugs we considered to have reliable data. The model contains five Abraham descriptors calculated by the ABSOLV program. The results show that Abraham descriptors can successfully predict human intestinal absorption if the human absorption data is carefully classified based on solubility and administration dose to humans.

In vitro activity of trovafloxacin against Bacteroides fragilis in mixed culture with either Escherichia coli or a vancomycin- resistant strain of Enterococcus faecium determined by an anaerobic time-kill technique

To determine the efficacy of trovafloxacin as a possible treatment for intra-abdominal abscesses, we have developed an anaerobic time-kill technique using different inocula to study the in vitro killing of Bacteroides fragilis in pure culture or in mixed culture with either Escherichia coli or a vancomycin-resistant strain of Enterococcus faecium (VREF). With inocula of 5 x 10(5) CFU/ml and trovafloxacin concentrations of </=2 microg/ml, a maximum observed effect (E(max)) of >/=6.1 (log(10) CFU/ml) was attained with all pure and mixed cultures within 24 h. With inocula of 10(8) CFU/ml, a similar E(max) and a similar concentration to produce 50% of E(max) (EC(50)) for B. fragilis were found in both pure cultures and mixed cultures with E. coli. However, to produce a similar killing of B. fragilis in the mixed cultures with VREF, a 14-fold increase in the concentration of trovafloxacin was required. A vancomycin-susceptible strain of E. faecium and a trovafloxacin-resistant strain of E. coli were also found to confer a similar "protective" effect on B. fragilis against the activity of trovafloxacin. Using inocula of 10(9) CFU/ml, the activity of trovafloxacin was retained for E. coli and B. fragilis and was negligible against VREF. We conclude that this is a useful technique to study the anaerobic killing of mixed cultures in vitro and may be of value in predicting the killing of mixed infections in vivo. The importance of using mixed cultures and not pure cultures is clearly shown by the difference in the killing of B. fragilis in the mixed cultures tested. Trovafloxacin will probably be ineffective in the treatment of infections involving large numbers of enterococci. However, due to its ability to retain activity against large cultures of B. fragilis and E. coli, trovafloxacin could be beneficial in the treatment of intra-abdominal abscesses.

Comparative pharmacokinetics of ciprofloxacin, gatifloxacin, grepafloxacin, levofloxacin, trovafloxacin, and moxifloxacin after single oral administration in healthy volunteers

In an open, randomized, six-period crossover study, the pharmacokinetics of ciprofloxacin, gatifloxacin, grepafloxacin, levofloxacin, moxifloxacin, and trovafloxacin were compared after a single oral dose in 12 healthy volunteers (6 men and 6 women). The volunteers received 250 mg of ciprofloxacin, 400 mg of gatifloxacin, 600 mg of grepafloxacin, 500 mg of levofloxacin, 400 mg of moxifloxacin, and 200 mg of trovafloxacin. The concentrations of the six fluoroquinolones in serum and urine were measured by a validated high-performance liquid chromatography method. Blood and urine samples were collected before and at different time points up to 48 h after medication. Levofloxacin had the highest peak concentration (C(max), in micrograms per milliliter) (6.21+/-1.34), followed by moxifloxacin (4.34+/-1.61) and gatifloxacin (3.42+/-0.74). Elimination half-lives ranged from 12.12+/-3.93 h (grepafloxacin) to 5.37+/-0.82 h (ciprofloxacin). The total areas under the curve (AUC(tot), in microgram-hours per milliliter) for levofloxacin (44.8+/-4.4), moxifloxacin (39.3+/-5.35), and gatifloxacin (30+/-3.8) were significantly higher than that for ciprofloxacin (5.75+/-1.25). Calculated from a normalized dose of 200 mg, the highest C(max)s (in micrograms per milliliter) were observed for levofloxacin (2.48 +/-0.53), followed by moxifloxacin (2.17+/-0.81) and trovafloxacin (2.09+/-0.58). The highest AUC(tot) (in microgram-hours per milliliter) for a 200-mg dose were observed for moxifloxacin (19.7+/-2.67) and trovafloxacin (19.5+/-3.1); the lowest was observed for ciprofloxacin (4.6+/-1.0). No serious adverse event was observed during the study period. The five recently developed fluoroquinolones (gatifloxacin, grepafloxacin, levofloxacin, moxifloxacin, and trovafloxacin) showed greater bioavailability, longer half-lives, and higher C(max)s than ciprofloxacin.

Alatrofloxacin-induced seizures during slow intravenous infusion

OBJECTIVE

To report a case of seizures associated with slow infusion (1-2 h) of alatrofloxacin, the prodrug of trovafloxacin.

CASE SUMMARY

A 37-year-old Asian man was admitted to the hospital for a distal pancreatectomy and drainage of a pseudocyst. Postoperative complications developed, which included peritonitis and pneumonia, requiring intensive care admission. Cultures from peritoneal drainage fluid and sputum isolated Klebsiella pneumoniae and Pseudomonas aeruginosa, respectively. He was treated with multiple courses of antibiotics, including intravenous gentamicin, metronidazole, vancomycin, meropenem, and ceftazidime. After three weeks, the patient still had sepsis and began therapy with alatrofloxacin in addition to ceftazidime and vancomycin. Alatrofloxacin infusion was administered according to product information instructions. Fifteen minutes after the first dose was started, the patient developed generalized clonus. On rechallenge, infusing at half the initial rate, the seizure recurred; consequently, the infusion was discontinued and replaced with intravenous ciprofloxacin and metronidazole. The patient remained seizure free thereafter.

DISCUSSION

Fluoroquinolones have been implicated in central nervous system adverse effects, including seizures, which have been reported with other fluoroquinolones but not with alatrofloxacin or trovafloxacin. In these reports, the patients often had preexisting risk factors such as increased age and electrolyte imbalances. The only apparent predisposition in this patient was mild hyponatremia.

CONCLUSIONS

Alatrofloxacin may cause seizures even during slow infusion. This case highlights the need for caution when commencing parenteral fluoroquinolone therapy, particularly with a new agent.

Comparison of the fluoroquinolones based on pharmacokinetic and pharmacodynamic parameters

Assessment of pharmacodynamic activity from standard in vitro minimum inhibitory concentrations (MICs) alone is insufficient to predict in vivo potency. Achievable serum and tissue concentrations as well as pharmacokinetic characteristics must be considered. When pharmacokinetic and pharmacodynamic values are combined, the area under the inhibitory curve (AUIC) and peak concentration:MIC ratio predict clinical cure for fluoroquinolones. Clinical data and animal models indicate that a peak:MIC of 10:1 and above and an AUIC of 125 and above are predictive of a clinical cure for this class of antimicrobials against gram-negative organisms. The values may be used to compare and contrast fluoroquinolones to determine which would be best for treating a specific microorganism. Pharmacodynamic data also can be used to design regimens that minimize the risk of suboptimal drug levels. Ensuring the optimal fluoroquinolone dosage based on pharmacodynamic principles would diminish the emergence of resistant organisms and prevent treatment failures.

Resistance to ciprofloxacin and the new fluoroquinolones

Resistance to ciprofloxacin has generally remained low in the UK. A low rate of resistance development in vitro has been suggested for the newer fluoroquinolones such as grepafloxacin and trovafloxacin. Levofloxacin is likely to have a pattern of development of resistance similar to that of ofloxacin. Resistance problems with ofloxacin are being reported in the USA, but it is unclear whether similar problems will arise with levofloxacin. Restrained quinolone use, surveillance of pathogen susceptibility and control of cross-infection with resistant clones remain important strategies for managing fluoroquinolone resistance.

Quinolones in the aged

Pharmacokinetic studies of fluoroquinolone antibacterials generally demonstrate some quantitative alterations in elderly compared with younger populations. The most common observations are an increased maximal plasma drug concentration and area under the concentration-time curve, which are primarily attributable to the 10 to 15% decrease in lean body mass in the elderly. For quinolones excreted primarily by the renal route, there is a prolongation in elimination half-life correlated with the aging-associated decline in creatinine clearance. Quinolones with major routes of nonrenal clearance will not usually show a prolongation in half-life because of compensatory relative increases in nonrenal mechanisms. Alterations directly attributable to aging alone, however, are minor, and vary between different quinolones. They do not justify a consistent need for dosage alterations on the basis of age alone. Agents with primarily renal excretion, such as ofloxacin or levofloxacin, may require dosage adjustment in the very elderly or the frail elderly, if significant decreases in creatinine clearance are present. No age-related differences in adverse effects of fluoroquinolones have been reported. Studies in both community-dwelling and institutionalised elderly populations have consistently shown quinolones to be as effective as comparative parenteral or oral therapy. While elderly populations may be at greater risk of adverse effects because of comorbidities and concurrent therapies, an increased occurrence of adverse events in elderly populations receiving quinolone antimicrobials relative to younger populations has not been reported.

Advances in antimicrobial therapy

Despite several decades of improved therapy and prevention of infectious diseases, infectious pathogens remain major causes of morbidity and mortality in humans worldwide. Among the most complex and daunting problems facing medical science is the evolution of antibiotic resistance among many common and once easily-treated infectious agents. This review summarizes the status of newer antimicrobial agents that have utility against pathogens infecting the central nervous system.

The new fluoroquinolones: A critical review

OBJECTIVE

This paper reviews the literature available on the new fluoroquinolones - clinafloxacin, gatifloxacin, grepafloxacin, levofloxacin, moxifloxacin, sparfloxacin and trovafloxacin - to compare these agents with each other and contrast them with ciprofloxacin, an older fluoroquinolone.

DATA SELECTION

Published papers used were obtained by searching MEDLINE for articles published between 1994 and 1998, inclusive. References of published papers were also obtained and reviewed. Abstracts from scientific proceedings were reviewed.

DATA EXTRACTION

Due to the limited data available on several of the agents, criteria for study inclusion in the in vitro, pharmacokinetics and in vivo sections were not restrictive.

DATA SYNTHESIS

The new fluoroquinolones offer excellent Gram-negative bacillary activity and improved Gram-positive activity (eg, against Streptococcus pneumoniae and Staphylococcus aureus) over ciprofloxacin. Clinafloxacin, gatifloxacin, moxifloxacin, sparfloxacin and trovafloxacin display improved activity against anaerobes (eg, Bacteriodes fragilis). All of the new fluoroquinolones have a longer serum half-life than ciprofloxacin (allowing for once daily dosing), and several are eliminated predominantly by nonrenal means. No clinical trials are available comparing the new fluoroquinolones with each other. Clinical trials comparing the new fluoroquinolones with standard therapy have demonstrated good efficacy in a variety of infections. Their adverse effect profile is similar to that of ciprofloxacin. Clinafloxacin and sparfloxacin cause a high incidence of phototoxicity (1.5% to 14% and 2% to 11.7%, respectively), grepafloxacin causes a high incidence of taste perversion (9% to 17%) and trovafloxacin causes a high incidence of dizziness (11%). They all interact with metal ion-containing drugs (eg, antacids), and clinafloxacin and grepafloxacin interact with theophylline. The new fluoroquinolones are expensive; however, their use may result in savings in situations where, because of their potent and broad spectrum of activity, they can be used orally in place of intravenous antibiotics.

CONCLUSIONS

The new fluoroquinolones offer advantages over ciprofloxacin in terms of improved in vitro activity and pharmacokinetics. Whether these advantages translate into improved clinical outcomes is presently unknown. The new fluoroquinolones have the potential to emerge as important therapeutic agents in the treatment of respiratory tract and genitourinary tract infections.

Trovafloxacin in combination with vancomycin against penicillin-resistant pneumococci in the rabbit meningitis model

Trovafloxacin, a new fluoroquinolone, produced bactericidal activity (-0.33 +/- 0.13 delta log10 CFU/ml.h; intravenously [i.v.] administered dose, 15 mg/kg) comparable to that of vancomycin (-0.39 +/- 0.18 delta log10 CFU/ml.h; i.v. admininistered dose, 20 mg/kg) in the treatment of experimental meningitis in rabbits due to a pneumococcal strain highly resistant to penicillin (MIC of penicillin G, 4 micrograms/ml). The combination of both drugs significantly increased (P < 0.05) the killing rate (-0.60 +/- 0.23 delta log10 CFU/ml.h) compared to that produced by either monotherapy. These results were also confirmed in vitro.

Trovafloxacin: an overview

Trovafloxacin, a new synthetic naphthyridine fluoroquinolone antibiotic, is a broad-spectrum agent available orally and intravenously. It was recently approved by the Food and Drug Administration for the treatment of selected pulmonary, surgical, intraabdominal, gynecologic, pelvic, skin, and urinary tract infections. Its spectrum of activity includes aerobic gram-positive and gram-negative organisms as well as anaerobic pathogens. It is rapidly absorbed after oral administration, achieves good tissue and cerebrospinal fluid penetration, and has a half-life that allows once-daily dosing. It is hepatically metabolized, and dosage adjustments are necessary for patients with severe hepatic dysfunction but not for those with mild or moderate dysfunction or renal dysfunction. The drug has a favorable safety profile, and a high tendency for transient first-dose dizziness and/or lightheadedness in young women. Similar to other quinolones, trovafloxacin should not be taken with antacids that contain aluminum or magnesium, sucralfate, or ferrous sulfate. Trovafloxacin may prove beneficial as it allows for oral or intravenous monotherapy against indicated infections that normally require multidrug, broad-spectrum antibiotic coverage.

Expanded activity and utility of the new fluoroquinolones: a review

In general, the fluoroquinolones developed over the past few years have greater potency, a broader spectrum of antimicrobial activity, greater in vitro efficacy against resistant organisms, and a better safety profile than other antimicrobial agents, including the older quinolones. The present review focuses on 4 new quinolones that are commercially available (levofloxacin, trovafloxacin, grepafloxacin, and sparfloxacin) and 3 that are currently undergoing clinical trials (gatifloxacin, moxifloxacin, and clinafloxacin). Examination of the minimum inhibitory concentrations of these drugs against gram-positive, gram-negative, anaerobic, and atypical organisms demonstrates their increased potency in vitro. The available clinical evidence, although sparse, suggests the potential enhanced efficacy of these drugs in the treatment of various community-acquired and nosocomial infections (eg, respiratory, urinary tract, and skin infections and sexually transmitted diseases). Compared with ciprofloxacin, their pharmacokinetic profiles demonstrate equivalent or greater bioavailability, higher plasma concentrations, and increased tissue penetration, as reflected in greater volume of distribution. Adverse events seen with most quinolones are mild. Serious adverse effects that may occur are phototoxicity (particularly with sparfloxacin) and prolongation of the QTc interval (seen with sparfloxacin and grepafloxacin). Drug interactions are possible between multivalent cation-containing compounds and all quinolones and between theophylline and both ciprofloxacin and grepafloxacin. Drugs that prolong the QTc interval should not be coadministered with sparfloxacin and grepafloxacin. Step-down therapy, a therapeutic and cost-saving advantage possible with gatifloxacin, levofloxacin, and moxifloxacin, allows the switching of patients from intravenous to oral therapy without having to change the dosage regimen or class of antibiotics. In addition to shortening the hospital stay and reducing the risk of venous complications, step-down therapy has been shown to cut hospital drug costs by 40% and hospitalization costs by 20%.

How do the newer oral antimicrobials stack up against traditional agents?

As the antibiotic arsenal expands with the development of new oral agents, selecting appropriate therapy is becoming more difficult. What are the therapeutic indications for the newer antimicrobials, and what advantages do they have over traditional agents? Drs Gleckman and De La Rosa discuss current issues related to antibiotic treatment and offer specific recommendations for the best use of the newer agents.

Safety of trovafloxacin in treatment of lower respiratory tract infections

Safety and toleration of oral trovafloxacin has been assessed in Phase III trials in patients with acute lower respiratory tract infections. Patients were treated orally with either trovafloxacin 100 or 200 mg (n=881) or a comparator (500 or 1000 mg amoxicillin, or 625 mg amoxicillin/clavulanic acid; n = 593). Adverse events were recorded in 112 (12.7%) trovafloxacin- and 74 (12.5%) comparator-treated patients. Frequency of effects on the autonomic nervous, musculoskeletal, respiratory, special senses, urinary and reproductive systems was <1%. Photosensitivity reactions were not reported in trovafloxacin-treated patients. Central or peripheral nervous system adverse effects (headache and dizziness) were slightly more common in trovafloxacin-treated patients (4.4% vs 1.9%). Patients treated with comparators experienced gastrointestinal events more frequently (6.1% vs 8.3%). Comparable incidences of adverse events were reported in patients > or = 65-years-old. Most events were mild to moderate in severity. Treatment was discontinued because of an adverse event in 18 (2%) trovafloxacin- and four (0.7%) comparator-treated patients. Despite the high prevalence of risk factors, serious adverse events were rare and the mortality rate over the 35-day study period was low: trovafloxacin 0.8%, comparator agents 1.5%. Laboratory test abnormalities were recorded in less than 1% of patients in either treatment group.