Multiple-dose pharmacokinetics and safety of trovafloxacin in healthy volunteers

Reactive metabolite of trovafloxacin activates inflammasomes: Implications for trovafloxacin-induced liver injury

Trovafloxacin is a quinolone antibiotic drug with broad-spectrum activity, which was withdrawn from a global market relatively soon after approval because of serious liver injury. The characteristics of trovafloxacin-induced liver injury are consistent with an idiosyncratic reaction; however, the details of the mechanism have not been elucidated. We examined whether trovafloxacin induces the release of damage-associated molecular patterns (DAMPs) that activate inflammasomes. We also tested ciprofloxacin, levofloxacin, gatifloxacin, and grepafloxacin for their ability to activate inflammasomes. Drug bioactivation was performed with human hepatocarcinoma functional liver cell-4 (FLC-4) cells, and THP-1 cells (human monocyte cell line) were used for the detection of inflammasome activation. The supernatant from the incubation of trovafloxacin with FLC-4 cells for 7 days increased caspase-1 activity and production of IL-1ß by THP-1 cells. In the supernatant of FLC-4 cells that had been incubated with trovafloxacin, heat shock protein (HSP) 40 was significantly increased. Addition of a cytochrome P450 inhibitor to the FLC-4 cells prevented the release of HSP40 from the FLC-4 cells and inflammasome activation in THP-1 cells by the FLC-4 supernatant. These results suggest that reactive metabolites of trovafloxacin can cause the release of DAMPs from hepatocytes that can activate inflammasomes. Inflammasome activation may be an important step in the activation of the immune system by trovafloxacin, which, in some patients, can cause immune-related liver injury.

Prediction of hepatic drug clearance with a human microfluidic four-cell liver acinus microphysiology system

Predicting human hepatic clearance remains a fundamental challenge in both pharmaceutical drug development and toxicological assessments of environmental chemicals, with concerns about both accuracy and precision of in vitro-derived estimates. Suggested sources of these issues have included differences in experimental protocols, differences in cell sourcing, and use of a single cell type, liver parenchymal cells (hepatocytes). Here we investigate the ability of human microfluidic four-cell liver acinus microphysiology system (LAMPS) to make predictions as to hepatic clearance for seven representative compounds: Caffeine, Pioglitazone, Rosiglitazone, Terfenadine, Tolcapone, Troglitazone, and Trovafloxacin. The model, whose reproducibility was recently confirmed in an inter-lab comparison, was constructed using primary human hepatocytes or human induced pluripotent stem cell (iPSC)-derived hepatocytes and 3 human cell lines for the endothelial, Kupffer and stellate cells. We calculated hepatic clearance estimates derived from experiments using LAMPS or traditional 2D cultures and compared the outcomes with both in vivo human clinical study-derived and in vitro human hepatocyte suspension culture-derived values reported in the literature. We found that, compared to in vivo clinically-derived values, the LAMPS model with iPSC-derived hepatocytes had higher precision as compared to primary cells in suspension or 2D culture, but, consistent with previous studies in other microphysiological systems, tended to underestimate in vivo clearance. Overall, these results suggest that use of LAMPS and iPSC-derived hepatocytes together with an empirical scaling factor warrants additional study with a larger set of compounds, as it has the potential to provide more accurate and precise estimates of hepatic clearance.

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.

Trovafloxacin-induced replication stress sensitizes HepG2 cells to tumor necrosis factor-alpha-induced cytotoxicity mediated by extracellular signal-regulated kinase and ataxia telangiectasia and Rad3-related

Use of the fluoroquinolone antibiotic trovafloxacin (TVX) was restricted due to idiosyncratic, drug-induced liver injury (IDILI). Previous studies demonstrated that tumor necrosis factor-alpha (TNF) and TVX interact to cause death of hepatocytes in vitro that was associated with prolonged activation of c-Jun N-terminal kinase (JNK), activation of caspases 9 and 3, and DNA damage. The purpose of this study was to explore further the mechanism by which TVX interacts with TNF to cause cytotoxicity. Treatment with TVX caused cell cycle arrest, enhanced expression of p21 and impaired proliferation, but cell death only occurred after cotreatment with TVX and TNF. Cell death involved activation of extracellular signal-related kinase (ERK), which in turn activated caspase 3 and ataxia telangiectasia and Rad3-related (ATR), both of which contributed to cytotoxicity. Cotreatment of HepG2 cells with TVX and TNF caused double-strand breaks in DNA, and ERK contributed to this effect. Inhibition of caspase activity abolished the DNA strand breaks. The data suggest a complex interaction of TVX and TNF in which TVX causes replication stress, and the downstream effects are exacerbated by TNF, leading to hepatocellular death. These results raise the possibility that IDILI from TVX results from MAPK and ATR activation in hepatocytes initiated by interaction of cytokine signaling with drug-induced replication stress.

Trovafloxacin enhances lipopolysaccharide-stimulated production of tumor necrosis factor-α by macrophages: role of the DNA damage response

Trovafloxacin (TVX) is a drug that has caused idiosyncratic, drug-induced liver injury (IDILI) in humans. In a murine model of IDILI, otherwise nontoxic doses of TVX and the inflammagen lipopolysaccharide (LPS) interacted to produce pronounced hepatocellular injury. The liver injury depended on a TVX-induced, small but significant prolongation of tumor necrosis factor-α (TNF) appearance in the plasma. The enhancement of TNF expression by TVX was reproduced in vitro in RAW 264.7 murine macrophages (RAW cells) stimulated with LPS. The current study was designed to identify the molecular target of TVX responsible for this response in RAW cells. An in silico analysis suggested a favorable binding profile of TVX to eukaryotic topoisomerase II-α (TopIIα), and a cell-free assay revealed that TVX inhibited eukaryotic TopIIα activity. Topoisomerase inhibition is known to lead to DNA damage, and TVX increased the DNA damage marker phosphorylated histone 2A.X in RAW cells. Moreover, TVX induced activation of the DNA damage sensor kinases, ataxia telangiectasia mutated (ATM) and Rad3-related (ATR). The ATR inhibitor NU6027 [6-(cyclohexylmethoxy)-5-nitrosopyrimidine-2,4-diamine] prevented the TVX-mediated increases in LPS-induced TNF mRNA and protein release, whereas a selective ATM inhibitor [2-(4-morpholinyl)-6-(1-thianthrenyl)-4H-pyran-4-one (KU55933)] was without effect. TVX prolonged TNF mRNA stability, and this effect was largely attenuated by NU6027. These results suggest that TVX can inhibit eukaryotic topoisomerase, leading to activation of ATR and potentiation of TNF release by macrophages, at least in part through increased mRNA stability. This off-target effect might contribute to the ability of TVX to precipitate IDILI in humans.

Unexpected link between an antibiotic, pannexin channels and apoptosis

Plasma membrane pannexin 1 channels (PANX1) release nucleotide find-me signals from apoptotic cells to attract phagocytes. In a small molecule screen, we discovered the quinolone antibiotic trovafloxacin as a novel PANX1 inhibitor. Although quinolones are widely used to treat bacterial infections, some quinolones have unexplained side effects, including deaths among children. PANX1 is a direct target of trovafloxacin at drug concentrations seen in human plasma, and its inhibition led to dysregulated fragmentation of apoptotic cells. Genetic loss of PANX1 phenocopied trovafloxacin effects, revealing a non-redundant role for pannexin channels in regulating cellular disassembly during apoptosis. Increase in drug-resistant bacteria worldwide and the dearth of new antibiotics is a major human health challenge. Comparing different quinolone antibiotics suggests that certain structural features may contribute to PANX1 blockade. These data identify a novel linkage between an antibiotic, pannexin channels, and cellular integrity, and suggest that re-engineering certain quinolones might help develop newer antibacterials.

Molecular mechanisms of hepatocellular apoptosis induced by trovafloxacin-tumor necrosis factor-alpha interaction

Idiosyncratic drug-induced liver injury (IDILI) continues to be a significant human health problem. IDILI is characterized as occurring in a minority of individuals exposed to a drug, yet it accounts for as much as 17% of all cases of acute liver failure. Despite these concerns, the mechanisms underlying IDILI remain unknown. Trovafloxacin (TVX), which causes IDILI in humans, also causes hepatocellular death in vitro when combined with tumor necrosis factor-alpha (TNF) treatment. However, the molecular mechanisms involved in this toxicity are not fully characterized. The purpose of this study was to identify mechanisms by which TVX and TNF interact to cause hepatocellular death, with a focus on a human hepatocyte cell line. TVX and TNF interacted to cause cytotoxicity in HepG2 cells at drug concentrations similar to those in people undergoing TVX therapy. TVX/TNF treatment caused apoptosis and DNA damage in HepG2 cells that depended on caspase activation. Prolonged activation of JNK occurred in TVX/TNF-induced cytotoxicity, and treatment with the JNK selective inhibitor SP600125 attenuated cytotoxicity. TVX/TNF cotreatment also caused cytotoxicity in isolated primary murine hepatocytes that was dependent on caspase activation. These results increase understanding of molecular signaling pathways involved in hepatocellular death caused by a drug with idiosyncratic liability in the presence of TNF.

Fluoroquinolone disposition: identification of the contribution of renal secretory and reabsorptive drug transporters

INTRODUCTION

Fluoroquinolones (FQs) exist as charged molecules in blood and urine making their absorption, distribution, and elimination likely to be influenced by active transport mechanisms. Greater understanding of in vivo FQ clearance mechanisms should help improve the predictability of drug-drug interactions, enhance the clinical safety and efficacy, and aid future novel drug design strategies.

AREAS COVERED

The authors present an overview of FQ development and associated drug-drug interactions, followed by systematic quantitative review of the physicochemical and in vivo pharmacokinetic properties for 15 representative FQs using historical clinical literature. These results were correlated with in vitro studies implicating drug transporters in FQ clearance to link clinical and in vitro evidence supporting the contribution of drug transport mechanisms to FQ disposition. Specific transporters likely to handle FQs in human renal proximal tubule cells are also identified.

EXPERT OPINION

Renal handling, that is, tubular secretion and reabsorption, appears to be the main determinant of FQ plasma half-life, clinical duration of action, and drug-drug interactions. Due to their zwitterionic nature, FQs are likely to interact with organic anion and cation transporters within the solute carrier (SLC) superfamily, including OAT1, OAT3, OCT2, OCTN1, OCTN2, MATE1, and MATE2. The ATP-binding cassette (ABC) transporters MDR1, MRP2, MRP4, and BCRP also may interact with FQs.

Relationship of quantitative structure and pharmacokinetics in fluoroquinolone antibacterials

AIM: To study the relationship between quantitative structure and pharmacokinetics (QSPkR) of fluoroquinolone antibacterials.

METHODS: The pharmacokinetic (PK) parameters of oral fluoroquinolones were collected from the litera-ture. These pharmacokinetic data were averaged, 19 compounds were used as the training set, and 3 served as the test set. Genetic function approximation (GFA) module of Cerius² software was used in QSPkR analysis.

RESULTS: A small volume and large polarizability and surface area of substituents at C-7 contribute to a large area under the curve (AUC) for fluoroquinolones. Large polarizability and small volume of substituents at N-1 contribute to a long half life elimination.

CONCLUSION: QSPkR models can contribute to some fluoroquinolones antibacterials with excellent pharmacokinetic properties.

Microarray analysis in human hepatocytes suggests a mechanism for hepatotoxicity induced by trovafloxacin

Idiosyncratic drug toxicity, defined as toxicity that is dose independent, host dependent, and usually cannot be predicted during preclinical or early phases of clinical trials, is a particularly confounding complication of drug development. An understanding of the mechanisms that lead to idiosyncratic liver toxicity would be extremely beneficial for the development of new compounds. We used microarray analysis on isolated human hepatocytes to understand the mechanisms underlying the idiosyncratic toxicity induced by trovafloxacin. Our results clearly distinguish trovafloxacin from other marketed quinolone agents and identify unique gene changes induced by trovafloxacin that are involved in mitochondrial damage, RNA processing, transcription, and inflammation that may suggest a mechanism for the hepatotoxicity induced by this agent. In conclusion, this work establishes the basis for future microarray analysis of new compounds to determine the presence of these expression changes and their usefulness in predicting idiosyncratic hepatotoxicity. Supplementary material for this article can be found on the HEPATOLOGY website (http://interscience. Wiley.com/jpages/0270-9139/suppmat/index.htnd).

The activity of grepafloxacin in two murine models of Mycobacterium avium infection

The activity against Mycobacterium avium complex (MAC) of varying doses of grepafloxacin (GRE; 25 mg/kg, 50 mg/kg, 100 mg/kg, and 200 mg/kg) were compared to clarithromycin (CLA; 100 mg/kg and 200 mg/kg), ethambutol (EMB; 100 mg/kg), and rifabutin (RBT; 10 mg/kg) using an intranasal (IN) infection model compared to an intravenous (IV) infection model. Beige mice (C57BL6/J-Lyst bg J/+) were infected intranasally with about 10(6) organisms and for the IV model about 10(7) organisms. Treatment for both models was started 1 week postinfection and given by gavage 5 days/week for 4 weeks. At the initiation of therapy, an early control group was killed to determine the initial organism load. Three days following the completion of therapy, drug-treated groups of mice and the late control group were killed and the response to therapy measured. The most effective agents were CLA and RBT. GRE and EMB had modest activities in both the IN and the IV models. A matched comparison between IN and IV challenges for each of the agents used revealed greater suppression of MAC in the IN model compared to the IV model.

Serum bactericidal activity of trovafloxacin, in combination with cefepime or amikacin, in healthy volunteers

OBJECTIVE

To investigate the phamacokinetics and serum bactericidal activities (SBAs) of trovafloxacin, cefepime and amikacin alone and trovafloxacin in combination with cefepime or amikacin, so that the most favorable combination with trovafloxacin can be determined.

METHODS

In this open, randomized, crossover study, 12 healthy volunteers (six females, six males; mean age +/- SD, 25.1 +/- 2.6 years) received an infusion of either 300 mg of alatrovafloxacin or 2000 mg of cefepime or 6 mg/kg body weight amikacin alone, or 300 mg of alatrovafloxacin plus 2000 mg of cefepime or plus 6 mg/kg body weight amikacin. The SBAs against Pseudomonas aeruginosa, Staphylococcus aureus (11 strains each), Citrobacter freundii and Acinetobacter spp. (10 strains each) 1, 10 and 24 h after drug administration were measured by a standard microdilution method. Concentrations of trovafloxacin, cefepime and amikacin in serum and urine were analyzed before and up to 10 and 12 h, respectively, after drug infusion.

RESULTS

Significant synergistic effects on SBA were observed with the combination of trovafloxacin and cefepime against P. aeruginosa, S. aureus and Acinetobacter spp. 1 h after drug administration, and against Citrobacter freundii 1, 10 and 24 h after drug administration. The combination of trovafloxacin and amikacin showed significant synergistic effects against P. aeruginosa, S. aureus and C. freundii 1 h after drug administration. The combination of trovafloxacin and cefepime was, in general, more active than the combination of trovafloxacin and amikacin. No significant differences in the serum concentrations of trovafloxacin were observed between single and combined administration. However, the maximal concentration of cefepime was significantly lower when it was used in combination with trovafloxacin.

CONCLUSION

Our study suggests a favorable interaction between trovafloxacin and cefepime. This combination showed more synergistic bactericidal activity against most of the test strains compared to the combination of trovafloxacin and amikacin. However, for P. aeruginosa, the bactericidal activity of cepefime alone was higher than that of the combination with trovafloxacin.

A critical review of the fluoroquinolones: focus on respiratory infections

The new fluoroquinolones (clinafloxacin, gatifloxacin, gemifloxacin, grepafloxacin, levofloxacin, moxifloxacin, sitafloxacin, sparfloxacin and trovafloxacin) offer excellent activity against Gram-negative bacilli and improved Gram-positive activity (e.g. against Streptococcus pneumoniae and Staphylococcus aureus) over ciprofloxacin. Ciprofloxacin still maintains the best in vitro activity against Pseudomonas aeruginosa. Clinafloxacin, gatifloxacin, moxifloxacin, sitafloxacin, sparfloxacin and trovafloxacin display improved activity against anaerobes (e.g. Bacteroides fragilis) versus ciprofloxacin. All of the new fluoroquinolones display excellent bioavailability and have longer serum half-lives than ciprofloxacin allowing for once daily dose administration. Clinical trials comparing the new fluoroquinolones to each other or to standard therapy have demonstrated good efficacy in a variety of community-acquired respiratory infections (e.g. pneumonia, acute exacerbations of chronic bronchitis and acute sinusitis). Limited data suggest that the new fluoroquinolones as a class may lead to better outcomes in community-acquired pneumonia and acute exacerbations of chronic bronchitis versus comparators. Several of these agents have either been withdrawn from the market, had their use severely restricted because of adverse effects (clinafloxacin because of phototoxicity and hypoglycaemia; grepafloxacin because of prolongation of the QTc and resultant torsades de pointes; sparfloxacin because of phototoxicity; and trovafloxacin because of hepatotoxicity), or were discontinued during developmental phases. The remaining fluoroquinolones such as gatifloxacin, gemifloxacin, levofloxacin and moxifloxacin have adverse effect profiles similar to ciprofloxacin. Extensive post-marketing safety surveillance data (as are available with ciprofloxacin and levofloxacin) are required for all new fluoroquinolones before safety can be definitively established. Drug interactions are limited; however, all fluoroquinolones interact with metal ion containing drugs (eg. antacids). The new fluoroquinolones (gatifloxacin, gemifloxacin, levofloxacin and moxifloxacin) offer several advantages over ciprofloxacin and are emerging as important therapeutic agents in the treatment of community-acquired respiratory infections. Their broad spectrum of activity which includes respiratory pathogens such as penicillin and macrolide resistant S. pneumoniae, favourable pharmacokinetic parameters, good bacteriological and clinical efficacy will lead to growing use of these agents in the treatment of community-acquired pneumonia, acute exacerbations of chronic bronchitis and acute sinusitis. These agents may result in cost savings especially in situations where, because of their potent broad-spectrum activity and excellent bioavailability, they may be used orally in place of intravenous antibacterials. Prudent use of the new fluoroquinolones will be required to minimise the development of resistance to these agents.

Commonly used antibacterial and antifungal agents for hospitalised paediatric patients: implications for therapy with an emphasis on clinical pharmacokinetics

Due to normal growth and development, hospitalised paediatric patients with infection require unique consideration of immune function and drug disposition. Specifically, antibacterial and antifungal pharmacokinetics are influenced by volume of distribution, drug binding and elimination, which are a reflection of changing extracellular fluid volume, quantity and quality of plasma proteins, and renal and hepatic function. However, there is a paucity of data in paediatric patients addressing these issues and many empiric treatment practices are based on adult data. The penicillins and cephalosporins continue to be a mainstay of therapy because of their broad spectrum of activity, clinical efficacy and favourable tolerability profile. These antibacterials rapidly reach peak serum concentrations and readily diffuse into body tissues. Good penetration into the cerebrospinal fluid (CSF) has made the third-generation cephalosporins the agents of choice for the treatment of bacterial meningitis. These drugs are excreted primarily by the kidney. The carbapenems are broad-spectrum beta-lactam antibacterials which can potentially replace combination regimens. Vancomycin is a glycopeptide antibacterial with gram-positive activity useful for the treatment of resistant infections, or for those patients allergic to penicillins and cephalosporins. Volume of distribution is affected by age, gender, and bodyweight. It diffuses well across serous membranes and inflamed meninges. Vancomycin is excreted by the kidneys and is not removed by dialysis. The aminoglycosides continue to serve a useful role in the treatment of gram-negative, enterococcal and mycobacterial infections. Their volume of distribution approximates extracellular space. These drugs are also excreted renally and are removed by haemodialysis. Passage across the blood-brain barrier is poor, even in the face of meningeal inflammation. Low pH found in abscess conditions impairs function. Toxicity needs to be considered. Macrolide antibacterials are frequently used in the treatment of respiratory infections. Parenteral erythromycin can cause phlebitis, which limits its use. Parenteral azithromycin is better tolerated but paediatric pharmacokinetic data are lacking. Clindamycin is frequently used when anaerobic infections are suspected. Good oral absorption makes it a good choice for step-down therapy in intra-abdominal and skeletal infections. The use of quinolones in paediatrics has been restricted and most information available is in cystic fibrosis patients. High oral bioavailability is also important for step-down therapy. Amphotericin B has been the cornerstone of antifungal treatment in hospitalised patients. Its metabolism is poorly understood. The half-life increases with time and can be as long as 15 days after prolonged therapy. Oral absorption is poor. The azole antifungals are being used increasingly. Fluconazole is well tolerated, with high bioavailability and good penetration into the CSF. Itraconazole has greater activity against aspergillus, blastomycosis, histoplasmosis and sporotrichosis, although it's pharmacological and toxicity profiles are not as favourable.

Fluoroquinolone adverse effects and drug interactions

Extensive pharmacologic and clinical development of quinolone antimicrobial agents has resulted in improved antimicrobial activity, pharmacokinetic features, toxicity, and drug-drug interaction profiles. Nalidixic acid and other early quinolones had limited use due to poor pharmacokinetics, relatively narrow antimicrobial spectrum of activity, and frequent adverse effects. Beginning with the development of fluoroquinolones, such as norfloxacin and ciprofloxacin, in the 1980s, the agents assumed a greatly expanded clinical role because of their broad antimicrobial spectrum of action, improved pharmacokinetic properties, and more acceptable safety profile. Although the pharmacokinetics and efficacy of the drugs have improved significantly, a major area of continued emphasis is to further reduce the frequency and severity of adverse events and drug-drug interactions. Older agents such as ciprofloxacin and ofloxacin are still extensively prescribed, but the focus of this article is on the newer fluoroquinolones (levofloxacin and other drugs that have been approved or have been under investigation since approximately 1997).

The Role of Quinolones in Upper Respiratory Tract Infections

Fluoroquinolones are widely used in clinical practice because of their advanced pharmacokinetic properties, potential activity against most bacterial species, excellent clinical responses, and few side effects. Quinolones have no role in the treatment of pharyngitis or simple otitis media. Until recently, the available fluoroquinolones were not indicated for the treatment of acute purulent sinusitis because of their perceived inactivity against Streptococcus pneumoniae. Although not generally considered to be drugs of first choice, older quinolones have efficacy similar to that of cephalosporins and b-lactams in randomized clinical trials. Well-conducted clinical trials have shown that the new fluoroquinolones are as effective as standard comparators in patients with suspected or proven acute bacterial sinusitis and may allow shorter treatment. Ciprofloxacin remains the fluoroquinolone of choice for chronic otitis media and malignant otitis media. The new "respiratory" fluoroquinolones have microbiologic and pharmacokinetic advantages over the older agents. Clinical trials have confirmed clinical activity, but superiority compared with older agents has not been conclusively shown. Trials devised to demonstrate clinical or pharmacoeconomic benefits are still required.

Comparative in vitro activity and pharmacodynamics of five fluoroquinolones against clinical isolates of Streptococcus pneumoniae

STUDY OBJECTIVE

To compare in vitro activity and pharmacodynamics of five fluoroquinolones against clinical isolates of Streptococcus pneumoniae.

DESIGN

In vitro analysis.

SETTING

University research laboratory.

INTERVENTION

Minimum inhibitory concentrations (MICs) were determined for penicillin and five fluoroquinolones by E test for 201 S. pneumoniae isolates. Serum concentration-time profiles were simulated for the following regimens: ciprofloxacin 750 mg orally every 12 hours and 400 mg intravenously every 8 hours; levofloxacin 500 mg orally and intravenously every 24 hours; trovafloxacin 200 mg orally and intravenously every 24 hours; gatifloxacin 400 mg orally and intravenously every 24 hours; and clinafloxacin 200 mg orally and intravenously every 12 hours.

MEASUREMENTS AND MAIN RESULTS

Free 24-hour areas under the serum concentration-time curves (AUC0-24) were calculated using the trapezoidal rule, and the average AUC0-24:MIC ratio was calculated for each regimen. Differences in ratios among agents were determined by analysis of variance (Scheffe post hoc test, p < 0.05). For intravenous dosing, the average AUC0-24:MIC for gatifloxacin, clinafloxacin, trovafloxacin, ciprofloxacin, and levofloxacin was 146, 142, 122, 71, and 61, respectively. For both oral and intravenous regimens, gatifloxacin and clinafloxacin ratios were significantly greater than those for trovafloxacin, levofloxacin, and ciprofloxacin (p < or = 0.007). Ratios for trovafloxacin were significantly greater than those for levofloxacin and ciprofloxacin (p < 0.0001), and levofloxacin and ciprofloxacin ratios were not significantly different from each other.

CONCLUSION

Gatifloxacin and clinafloxacin achieve significantly higher AUC0-24:MIC ratios for S. pneumoniae than trovafloxacin, levofloxacin, and ciprofloxacin. Large comparative studies are necessary to determine the clinical significance of these findings.

Pharmacokinetics of intravenous trovafloxacin in critically ill adults

The pharmacokinetic disposition of numerous antimicrobial agents is altered in critically ill patients. Pharmacokinetics of trovafloxacin, a fluoroquinolone indicated specifically for severe, life-threatening infections in the intensive care unit, have not been well studied in this population. We characterized the pharmacokinetic disposition of trovafloxacin after administration of alatrofloxacin, the intravenous prodrug, in critically ill adults. Seven patients (3 men, 4 women; mean +/- SD age 59.4 +/- 20.6 yrs; baseline aspartate aminotransferase [AST]/alanine aminotransferase [ALT] 66.0 +/- 40.6/51.5 +/-37.5 IU/L; median Acute Physiology and Chronic Health Evaluation [APACHE II] score 27, range 15-32) were studied at estimated steady state. Calculated (mean +/- SD) half-life, clearance at steady state, and volume of distribution in all patients were 10.9 +/- 1.8 hours, 161.3 +/- 41.1 ml/minute, and 1.4 +/- 0.4 L/kg. In patients receiving 300 mg, maximum concentration, minimum concentration, and area under the curve from 0-24 hours were 3.6 +/- 0.5 mg/L, 0.6 +/- 0.3 mg/L, and 34.2 +/- 10.6 mg x hr/L, respectively. These results are consistent with published values in other patient populations, indicating that trovafloxacin pharmacokinetics are not substantially altered in critically ill patients with normal or mildly impaired hepatic function.

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.

A phase-II study of trovafloxacin for the treatment of Chlamydia trachomatis infections

BACKGROUND

Chlamydia trachomatis can cause an insidious, asymptomatic infection in both men and women. Trovafloxacin, a fluoronaphthyridone antibiotic related to the fluoroquinolones, has broad antibacterial activity that encompasses C. trachomatis.

GOAL OF STUDY

We designed a phase-II study to determine the efficacy and safety of trovafloxacin for chlamydial infections.

STUDY DESIGN

Four once-daily dosing regimens were used: 200 mg for 7 days, 200 mg for 5 days, 100 mg for 7 days, and 50 mg for 7 days.

RESULTS

Sixty-four men and 66 women were enrolled. Of the 73 bacteriologically evaluable patients, 20 received 200 mg for 7 days, 18 received 200 mg for 5 days, 14 received 100 mg for 7 days, and 21 received 50 mg for 7 days. Bacteriologic failure occurred in 1 patient (5%) in the 200-mg 7-day group, 2 patients (14%) in the 100-mg group, and 1 patient (5%) in the 50-mg group. No clinical failures were noted among the 30 C. trachomatis infected men with nongonococcal urethritis, although 1 patient had only improved at the final visit. Safety data were available from 119 patients. Of 86 patients receiving the three highest dosing regimens, 17 (20%) had at least one adverse event, judged treatment-related in only 9 (10 %). Of 33 patients receiving the lowest dose, 5 (15%) had an adverse event, three (9%) of which were considered treatment related. No adverse event was severe.

CONCLUSION

In doses ranging from 200 mg to 50 mg daily for a week and 200 mg daily for 5 days, trovafloxacin appears to be effective for chlamydial infections and is well tolerated.

Potential interactions of the extended-spectrum fluoroquinolones with the CNS

The new generation fluoroquinolones -- sparfloxacin, levofloxacin, grepafloxacin and trovafloxacin -- have been designed to respond to the clinical need for extended antimicrobial cover in the face of increasing global microbial resistance. Their main focus is in the treatment of respiratory infections, particularly those acquired in the community. CNS adverse effects, such as dizziness and headache, are known to occur relatively commonly with some fluoroquinolones and are not, in general, well tolerated by patients. The structural component of the fluoroquinolone molecule believed to be responsible for improved gram-positive activity is also believed to be implicated in the production of CNS adverse effects, including those arising from drug interactions with theophylline and NSAIDs. Inhibition of brain gamma-aminobutyric acid (GABA) receptor binding appears to be a strong indicator of CNS activity, though N-methyl-D-aspartate receptor binding has also been implicated. In accordance with the results of these predictive studies, clinical trials have found sparfloxacin, levofloxacin and grepafloxacin to be associated with a low incidence of CNS events. Trovafloxacin has been found to be associated with a higher incidence of CNS events (particularly lightheadedness and dizziness) than the other 3 agents. Ongoing and future clinical studies will help to define the usefulness of the predictive models, as well as reveal the full CNS adverse event profile of these and other investigational fluoroquinolones.

Activities of trovafloxacin compared with those of other fluoroquinolones against purified topoisomerases and gyrA and grlA mutants of Staphylococcus aureus

Frequencies of mutation to resistance with trovafloxacin and four other quinolones were determined with quinolone-susceptible Staphylococcus aureus RN4220 by a direct plating method. First-step mutants were selected less frequently with trovafloxacin (1.1 x 10(-10) at 2 to 4x the MIC) than with levofloxacin or ciprofloxacin (3.0 x 10(-7) to 3.0 x 10(-8) at 2 to 4x the MIC). Mutants with a change in GrlA (Ser80-->Phe or Tyr) were most commonly selected with trovafloxacin, ciprofloxacin, levofloxacin, or pefloxacin. First-step mutants were difficult to select with sparfloxacin; however, second-step mutants with mutations in gyrA were easily selected when a preexisting mutation in grlA was present. Against 29 S. aureus clinical isolates with known mutations in gyrA and/or grlA, trovafloxacin was the most active quinolone tested (MIC at which 50% of isolates are inhibited [MIC(50)] and MIC(90), 1 and 4 microg/ml, respectively); in comparison, MIC(50)s and MIC(90)s were 32 and 128, 16 and 32, 8 and 32, and 128 and 256 microg/ml for ciprofloxacin, sparfloxacin, levofloxacin, and pefloxacin, respectively. Strains with a mutation in grlA only were generally susceptible to all of the quinolones tested. For mutants with changes in both grlA and gyrA MICs were higher and were generally above the susceptibility breakpoint for ciprofloxacin, sparfloxacin, levofloxacin, and pefloxacin. Addition of reserpine (20 microg/ml) lowered the MICs only of ciprofloxacin fourfold or more for 18 of 29 clinical strains. Topoisomerase IV and DNA gyrase genes were cloned from S. aureus RN4220 and from two mutants with changes in GrlA (Ser80-->Phe and Glu84-->Lys). The enzymes were overexpressed in Escherichia coli GI724, purified, and used in DNA catalytic and cleavage assays that measured the relative potency of each quinolone. Trovafloxacin was at least five times more potent than ciprofloxacin, sparfloxacin, levofloxacin, or pefloxacin in stimulating topoisomerase IV-mediated DNA cleavage. While all of the quinolones were less potent in cleavage assays with the altered topoisomerase IV, trovafloxacin retained its greater potency relative to those of the other quinolones tested. The greater intrinsic potency of trovafloxacin against the lethal topoisomerase IV target in S. aureus contributes to its improved potency against clinical strains of S. aureus that are resistant to other quinolones.

Pharmacodynamics of trovafloxacin in a mouse model of cephalosporin-resistant Streptococcus pneumoniae pneumonia

Trovafloxacin is a potentially useful agent for treatment of infections caused by cephalosporin-resistant Streptococcus pneumoniae. We studied the effectiveness of trovafloxacin therapy and examined the correlation between pharmacodynamic indices in serum and lung, and bacterial killing. Immunocompetent Balb/c mice were infected by intranasal inoculation of a cephalosporin-resistant S. pneumoniae isolate (MIC of ceftriaxone and trovafloxacin 2 and 0.06 mg/L, respectively). Trovafloxacin 10-30 mg/kg/day in one or three divided doses was started 15 h after infection. Serum and lung drug concentrations were measured at multiple time points for 24 h. Serum concentrations peaked at 30-60 min and lung concentrations approximately 30 min later. The serum T1/2 was approximately 9 h and lung T1/2 varied from 5 to 9 h. Lung AUC and Cmax values were 2-3 times greater than those in serum. At the start of therapy lung bacterial concentrations were 8.4 +/- 0.3 log10 cfu/mL and 24 h later had decreased by 3.5 +/- 0.2, 4.0 +/- 0.2, 0.8 +/- 0.3 and 1.0 +/- 1.2 log10 cfu/mL with 30 mg/kg x 1, 10 mg/kg x 3, 10 mg/kg x 1 and 3.3 mg/kg x 3 regimens, respectively. Although the larger dosages were more effective (P < 0.001) the differences between divided and single dosage regimens were not significant. Trovafloxacin serum AUC/MIC ratio correlated best with bacterial killing in the lungs over 24 h. Trovafloxacin is likely to be useful in the treatment of cephalosporin-resistant S. pneumoniae pneumonia.

Effects of food on the pharmacokinetics of sparfloxacin

Sparfloxacin, a fluoroquinolone with a broad antimicrobial spectrum and long elimination half-life, is indicated for the treatment of community-acquired pneumonia and acute bacterial exacerbations of chronic bronchitis in adult patients. The present study was undertaken to determine the effects of skim milk and a high-fat breakfast without milk on the single-dose pharmacokinetic characteristics of this antibiotic. The pharmacokinetics of a single 200-mg dose of sparfloxacin were assessed in a 3-way crossover study that included 23 healthy male volunteers who had fasted, had ingested 240 mL of skim milk, or had consumed a standard high-fat breakfast. The subjects' mean age and weight were 26.5 years and 73.2 kg, respectively; 17 were white, 5 Hispanic, and 1 black. Neither skim milk nor the high-fat breakfast had a statistically significant effect on sparfloxacin absorption, as reflected in the maximum plasma concentration (Cmax) and area under the plasma concentration-time curve (AUC). Ninety percent confidence limits for logarithmically transformed AUC from time zero to infinity and Cmax were within the 80% to 125% range, demonstrating that the rate and extent of sparfloxacin absorption with skim milk or a high-fat breakfast were not different from those under fasted conditions. As indicated by an increase in the time to Cmax from 3.6 to 5.4 hours, the high-fat breakfast slightly delayed the onset of sparfloxacin absorption. Skim milk and the high-fat breakfast did not significantly affect the elimination kinetics of sparfloxacin. Sparfloxacin was well tolerated in all 3 treatment groups. Despite the apparent delay in the onset of absorption, the bioavailability of sparfloxacin in the healthy male subjects in this study population was not affected by concomitant administration with skim milk or a high-fat meal. Accordingly, the results suggest that sparfloxacin can be administered without regard to the ingestion of milk or meals.

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.

Pharmacodynamics of trovafloxacin, ofloxacin, and ciprofloxacin against Streptococcus pneumoniae in an in vitro pharmacokinetic model

An in vitro pharmacokinetic model was used to simulate the pharmacokinetics of trovafloxacin, ofloxacin, and ciprofloxacin in human serum and to compare their pharmacodynamics against eight Streptococcus pneumoniae strains. The MICs of ofloxacin and ciprofloxacin ranged from 1 to 2 micrograms/ml. Trovafloxacin was 8- to 32-fold more potent, with MICs of 0.06 to 0.12 microgram/ml. Logarithmic-phase cultures were exposed to peak concentrations of trovafloxacin, ofloxacin, or ciprofloxacin achieved in human serum after 200-, 400-, and 750-mg oral doses, respectively. Trovafloxacin was dosed at 0 and 24 h, and ofloxacin and ciprofloxacin were dosed at 0, 12, and 24 h. Human elimination pharmacokinetics were simulated, and viable bacterial counts were measured at 0, 2, 4, 6, 8, 12, 24, and 36 h. Trovafloxacin was rapidly and significantly bactericidal against all eight strains evaluated, with viable bacterial counts decreasing at least 5 logs to undetectable levels. Times to 99.9% killing were only 1 to 3 h. Although the rate of killing with ofloxacin was substantially slower than that with trovafloxacin, ofloxacin was also able to eradicate all eight strains from the model, despite a simulated area under the inhibitory curve/MIC ratio (AUC/MIC) of only 49. In contrast, ciprofloxacin eradicated only five strains (AUC/MIC = 44) from the model. Against the other three strains (AUC/MIC = 22), the antibacterial activity of ciprofloxacin was substantially diminished. These data corroborate clinical data and suggest that trovafloxacin has a pharmacodynamic advantage over ciprofloxacin and ofloxacin against S. pneumoniae in relation to its enhanced antipneumococcal activity.

Absolute bioavailability of moxifloxacin

Moxifloxacin (BAY 12-8039) is an investigational 8-methoxy-fluoroquinolone with broad-spectrum gram-positive and gram-negative activity. To determine the absolute bioavailability of moxifloxacin, this open-label, randomized, crossover study compared the pharmacokinetic characteristics of a single 100-mg dose administered either orally or intravenously as a 60-minute infusion in 10 healthy male volunteers (mean age [+/- SD], 29.3+/-7.1 years; mean weight [+/- SD], 77.7+/-8.7 kg). Geometric mean values for oral/IV moxifloxacin were as follows: peak serum concentration, 1.15/1.34 mg/L, and area under the concentration-time curve over 48 hours, 9.86/10.89 mg x h/L. The geometric mean absolute bioavailability of oral moxifloxacin was 91.8%. Mean renal clearance was approximately 2.3 L/h after administration of both the single oral and IV formulations, which suggests lack of active tubular secretion of moxifloxacin. Both the oral and IV formulations were well tolerated, with 5 reported possible or probable drug-related adverse events; they included headache, nausea, and localized urticaria. In summary, a single oral dose of moxifloxacin was extensively absorbed in healthy young men. Further studies are necessary in actual patients to confirm the viability of IV to oral conversion at the same dose of moxifloxacin.

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.

Trovafloxacin: a new fluoroquinolone

OBJECTIVE

To review the pharmacology, antimicrobial activity, pharmacokinetics, clinical efficacy, and safety of trovafloxacin.

DATA SOURCES

A MEDLINE search (January 1966-April 1998) was conducted for relevant literature using the terms CP-99,219, CP-116,519, trovafloxacin, and alatrofloxacin. Abstracts published by the American Society of Microbiology during 1995-1997 meetings were also reviewed.

STUDY SELECTION AND DATA EXTRACTION

All in vitro, animal, and human studies were reviewed for the antimicrobial activity, pharmacokinetics, efficacy, and safety of trovafloxacin.

DATA SYNTHESIS

Trovafloxacin is a new fluoroquinolone with enhanced activity against gram-positive and anaerobic microorganisms. The oral bioavailability under fasting conditions is approximately 88%. The elimination half-life of trovafloxacin is approximately 10 hours. Less than 10% of trovafloxacin is eliminated unchanged in the urine. Trovafloxacin is effective in the treatment of community-acquired pneumonia and nosocomial pneumonia with cure rates of > 90% and 77%, respectively. Trovafloxacin is comparable with ceftriaxone in the treatment of meningococcal meningitis in children; each produces a cure rate of approximately 90%. In treatment of uncomplicated urinary tract infection, both ciprofloxacin and trovafloxacin achieve an eradication rate of > or = 93%. Trovafloxacin is similar to ofloxacin in the treatment of urogenital Chlamydia trachomatis and acute exacerbations of chronic bronchitis, with clinical success in 97% of patients with each drug. The common adverse effects of trovafloxacin include dizziness, headache, and gastrointestinal intolerance.

CONCLUSIONS

The advantages of once-daily dosing and enhanced activity of trovafloxacin against gram-positive and anaerobic organisms may expand its use over available fluoroquinolones. Further studies are needed to define its role in the treatment of various infectious diseases.

Comparative efficacy of trovafloxacin in experimental endocarditis caused by ciprofloxacin-sensitive, methicillin-resistant Staphylococcus aureus

The new fluoroquinolone trovafloxacin was tested against a ciprofloxacin-sensitive, methicillin-resistant Staphylococcus aureus strain in the rabbit model of endocarditis. Trovafloxacin was more effective than vancomycin (CFU/g of vegetation, 2.65 +/- 1.87 versus 4.54 +/- 2.80 [mean +/- standard deviation]; P < 0.05) or ampicillin-sulbactam plus rifampin (4.9 +/- 1.1 CFU/g). The addition of ampicillin-sulbactam to trovafloxacin tended to reduce titers further.

Pharmacodynamics and microbiology of trovafloxacin in animal models of surgical infection

Trovafloxacin provides broad in vitro and in vivo coverage of the aerobic and anaerobic pathogens found frequently in surgical infections. In vitro susceptibility testing indicated that trovafloxacin inhibited gram-positive staphylococci and enterococci, numerous gram-negative organisms, including Escherichia coli, and anaerobic pathogens, such as Bacteroides fragilis. Trovafloxacin protected mice from lethal infections induced by gram-negative or gram-positive organisms, even when these organisms were inoculated in combination with B. fragilis. Trovafloxacin protected rats in models of intra-abdominal sepsis induced by inoculation with E. coli and B. fragilis or with multiple aerobic and anaerobic pathogens. In these experimental models, trovafloxacin protected rats from lethal infection, reduced intra-abdominal abscess formation, and inhibited bacterial growth. Drug concentrations were greater in intra-abdominal abscesses than in serum, reflecting the good tissue penetration of trovafloxacin. These results indicate that trovafloxacin may be effective in prophylaxis and treatment of mixed infections in surgical patients.

Overview of quinolones in the treatment and prevention of surgical infection

Postoperative infection remains a complication of surgical procedures, resulting in increased morbidity, mortality, and cost. The frequent polymicrobial etiology and emerging patterns of resistance continue to compromise cure rates. Although quinolones have many attractive properties for the surgical setting, combination therapy is routinely indicated for appropriate coverage. Advanced-generation quinolones, such as trovafloxacin, offer an increased antimicrobial spectrum, including activity against important surgical pathogens, and longer elimination half-lives. These newer agents may be used intravenously or orally as once-daily single-agent therapy for surgical prophylaxis, and in place of combination therapy for complex intra-abdominal and pelvic infections.

The bioavailability of nasogastric versus tablet-form oral trovafloxacin in healthy subjects

BACKGROUND

Patients in the hospital, as well as those in home care settings, often require nutritional supplementation with enteral feeding solutions. In addition, patients with serious infections who are clinically unstable often cannot maintain adequate intake by mouth and may require an alternative to oral antibiotic administration. However, delivery of crushed oral formulations of drugs via nasogastric tubes is often carried out without adequate bioavailability data, and this method of administration may not always be equivalent to oral drug delivery.

METHODS

In an open-label, randomized, four-period, four-treatment, cross-over study, 24 healthy volunteers were given one dose of each of the following treatments, with a 7-day wash-out between dosing periods: Treatment A: two 100-mg trovafloxacin tablets given orally with 240 mL water; Treatment B: two crushed 100-mg trovafloxacin tablets suspended in water and administered through a nasogastric tube into the stomach; Treatment C: two crushed 100-mg trovafloxacin tablets suspended in water and administered through a nasogastric tube into the duodenum; or Treatment D: two crushed 100-mg trovafloxacin tablets suspended in water and given through a nasogastric tube into the stomach concomitantly with an enteral feeding solution (240 mL full-strength Osmolite).

RESULTS

Pharmacokinetic analyses showed that the bioavailability of trovafloxacin after administration of crushed tablets into the stomach with or without concomitant enteral feeding was not significantly different from that of the orally administered whole tablets: the 90% confidence limits of the area under the concentration-time curve (AUC(0-infinity)) for Treatment B versus Treatment A (91.3%, 109.5%) and Treatment D versus Treatment A (91.6%, 109.9%) were well within the bioequivalence criteria of 80% to 125%. Results of analysis of variance (ANOVA) indicated no significant sequence, period, or treatment-by-period interaction effects. Administration of trovafloxacin into the duodenum (Treatment C) resulted in reduced systemic exposure to trovafloxacin, with a 31% decrease in AUC(0-infinity) and a 30% decrease in peak serum concentration (Cmax) compared to oral administration. Time to peak serum concentration (Tmax) was 1.7 hours after oral administration of trovafloxacin and 1.1 hours after administration directly into the stomach or duodenum through a nasogastric tube in the absence of concomitant enteral feeding. All four treatments were well tolerated; no participant discontinued the study due to adverse events and no serious adverse events were reported.

CONCLUSIONS

These results showed that administration of crushed trovafloxacin tablets through a nasogastric tube into the stomach, with or without concomitant enteral feeding, achieves absorption and tolerability comparable to those of orally administered trovafloxacin tablets.

A double-blind, placebo-controlled, parallel group study of oral trovafloxacin on bowel microflora in healthy male volunteers

BACKGROUND

Treatment with oral antibiotic drugs generally influences normal fecal flora. These changes can be both beneficial (eg, elimination of aerobic, gram-negative bacilli) and detrimental (eg, the appearance of resistant pathogenic micro-organisms). Trovafloxacin, a new fluoroquinolone with in vitro activity against anaerobes, and gram-negative, gram-positive, and atypical pathogens, is a potentially beneficial antimicrobial for bowel sterilization. This double-blind trial investigated the effect of trovafloxacin on the normal microbial bowel flora of healthy male subjects.

METHODS

Subjects were randomized (in a 2:1 ratio) to receive either 200 mg trovafloxacin once daily for 10 days or a matching placebo. Fecal samples were collected at two baseline occasions, on visit days 4, 7, 10, and 17, and at follow-up. Bacterial species were identified and quantified in the fecal samples.

RESULTS

Twelve subjects received the active drug and seven received placebo. No Enterobacteriaceae were found in samples from days 4 to 10 in subjects receiving trovafloxacin. No changes in Enterobacteriaceae were found throughout the study in subjects receiving placebo. Incidental Enterobacteriaceae were isolated from subjects in the trovafloxacin group at the end of the study. No clinically significant differences were found in either group with respect to prevalence, appearance, or disappearance of aerobic gram-positive cocci, anaerobic bacteria, or yeasts. All tested Enterobacteriaceae were highly susceptible to trovafloxacin. No increase in minimum inhibitory concentration values was seen in day 17 and follow-up samples for isolated Escherichia coli strains. No Clostridium difficile was found in day 17 or follow-up samples from subjects in the trovafloxacin group. All tests for clostridium toxin were negative.

CONCLUSIONS

During the treatment period, E. coli could not be cultured from the feces of the 12 healthy subjects receiving 200 mg trovafloxacin daily during days 4 to 10. All isolated Enterobacteriaceae were susceptible to trovafloxacin and no changes in susceptibility were found after the treatment period. In subjects treated with trovafloxacin, the prevalence and number of gram-positive bacteria were rapidly reduced. Trovafloxacin is able to selectively and reversibly suppress bowel flora.

The pharmacokinetic effects of coadministration of morphine and trovafloxacin in healthy subjects

BACKGROUND

Morphine and antibiotics are frequently coadministered in the surgical setting. These agents may interact, reducing the efficacy of the antibiotic or increasing the toxicity of morphine. It is therefore important to determine whether antibiotics that might be used for surgical prophylaxis have the potential to change the pharmacokinetics of morphine. It is equally important to learn whether morphine affects the plasma levels of antibiotics and thus may potentially influence their efficacy or tolerability.

METHODS

This open, randomized, placebo-controlled, three-treatment, three-period cross-over study enrolled 19 healthy volunteers. Oral trovafloxacin (200 mg), a novel fluoroquinolone antibiotic, and intravenous morphine (0.15 mg/kg) were coadministered, and the effects on the pharmacokinetics of each drug and on changes in the pharmacologic action of morphine, estimated from its effects on respiratory rate and level of sedation, were examined.

RESULTS

When trovafloxacin was coadministered with morphine, the half-life of trovafloxacin was unchanged; however, the ratio of the area under the serum concentration versus time curve (AUC(0-infinity)) estimates for trovafloxacin/morphine versus trovafloxacin/placebo was 63.8% (95% confidence interval [CI], 40.7% to 100.3%), indicating a 36% reduction in the bioavailability of trovafloxacin. The ratio of the mean maximum serum concentration (Cmax) estimates of trovafloxacin for the two treatments was 53.8% (95% CI: 36.1% to 80.1%), indicating a 46% reduction in Cmax. The time to Cmax was delayed by 4 hours. With trovafloxacin coadministration, there were no statistically significant changes in either the mean relative bioavailability of morphine or that of its metabolite, 6beta-glucuronide-morphine. Coadministration of trovafloxacin did not exacerbate the reduction in respiratory rate or increase the number of side effects associated with morphine administration.

CONCLUSIONS

Coadministration of trovafloxacin and morphine reduces the bioavailability and maximum serum concentrations of trovafloxacin. However, elimination of oral trovafloxacin is not impaired, suggesting that the efficacy of trovafloxacin could be maintained in many patients who receive concomitant morphine. Morphine plasma levels and pharmacologic effects are not significantly altered by coadministration of trovafloxacin. Despite their similar metabolic pathways, the trovafloxacin/morphine combination neither exacerbates the respiratory depressant effects of morphine nor increases the frequency of side effects when compared with placebo/morphine treatment. These results suggest that the efficacy of trovafloxacin may be maintained when coadministered with morphine. Concurrent administration of trovafloxacin and morphine is unlikely to alter the pharmacologic effects of morphine.

Concentrations of trovafloxacin in colonic tissue and peritoneal fluid after intravenous infusion of the prodrug alatrofloxacin in patients undergoing colorectal surgery

BACKGROUND

Trovafloxacin is a new fourth-generation fluoroquinolone whose pharmacokinetics and in vitro activity suggest that it is well suited for antibiotic prophylaxis in elective colorectal surgery. Alatrofloxacin is a prodrug that is rapidly hydrolyzed to trovafloxacin in the body.

METHODS

Twelve patients received a single dose of alatrofloxacin equivalent to 200 mg trovafloxacin by intravenous infusion over 1 hour. Surgery was started at various time points relative to infusion time to allow determination of trovafloxacin concentrations in serum, colonic tissue, and peritoneal fluid as a function of time.

RESULTS

The concentration in the earliest colonic tissue sample (1.4 hours after dosing) was 1.4 microg/g. The maximum colonic tissue concentration was 2.8 microg/g in a sample taken 2 hours after dosing. Colonic tissue/serum concentration ratios in samples taken 2-10 hours after the end of infusion ranged from 0.8 to 1.47. Concentrations of trovafloxacin in peritoneal fluid ranged from below the level of quantitation to 2.1 microg/mL at the time of colonic tissue sampling and from below the level of quantitation to 2.5 microg/mL at the time of wound closure. Alatrofloxacin was well tolerated.

CONCLUSIONS

After a single intravenous dose of alatrofloxacin equivalent to 200 mg trovafloxacin, trovafloxacin is distributed rapidly into colonic tissue and peritoneal fluids. Tissue concentrations approximate serum concentrations and decline in parallel for up to 10 hours after dosing.

Oral trovafloxacin compared with intravenous cefoxitin in the prevention of bacterial infection after elective vaginal or abdominal hysterectomy for nonmalignant disease. Trovafloxacin Surgical Group

BACKGROUND

Trovafloxacin is a new fourth-generation fluoroquinolone whose pharmacokinetics and in vitro activity suggest that it is well suited for antibiotic prophylaxis in elective hysterectomy.

METHODS

In a randomized, double-blind, multicenter study, parallel groups of women 18 years of age or older received either 200 mg trovafloxacin by mouth and intravenous (i.v.) placebo or 2 g cefoxitin by i.v. infusion and placebo by mouth before elective vaginal or abdominal hysterectomy for nonmalignant disease.

RESULTS

In the 103 and 97 patients in the trovafloxacin and cefoxitin groups, respectively, who were evaluable for efficacy, the prophylactic success rates at hospital discharge (96% in both groups) and 30 +/- 6 days after hysterectomy (88% and 91% in the trovafloxacin and cefoxitin groups, respectively) were statistically equivalent. Both antibiotics were well tolerated.

CONCLUSION

A single oral 200 mg dose of trovafloxacin is as effective and safe as a standard cefoxitin parenteral regimen in the prevention of primary bacterial infection after elective vaginal or abdominal hysterectomy for nonmalignant disease.

Treatment of experimental Staphylococcus epidermidis endophthalmitis with oral trovafloxacin

PURPOSE

To investigate the ocular pharmacokinetics and efficacy of oral trovafloxacin, a novel fluoroquinolone antibiotic, in Staphylococcus epidermidis endophthalmitis.

METHODS

Albino rabbits (n = 20) were infected with an intravitreal inoculum of S epidermidis (1.0 x 10(8) colony-forming units [CFU/0.1 ml) and 24 hours later received a single oral dose of trovafloxacin (250 mg/kg). Serum and intraocular samples from infected and control (noninfected) eyes were obtained up to 24 hours after antibiotic administration for measurement of trovafloxacin levels. A second group of rabbits (n = 72) was infected intraocularly and randomized 24 hours later to oral trovafloxacin (250 mg/kg twice a day) for 6 days or no treatment (control). Treatment efficacy was assessed by vitreous culture, clinical examination, and histopathology.

RESULTS

Following a single dose of trovafloxacin, maximal vitreous levels were achieved at 8 hours in infected eyes, with a penetration ratio of 36%. Vitreous levels were greater than 15 times the minimum inhibitory concentration of the strain employed. In animals with established endophthalmitis, treated eyes were sterilized after 5 days (P = .0495) compared with control eyes, which autosterilized at 14 days. Clinical and histologic examination revealed significant amelioration of anterior segment inflammation in treated eyes, although severe destruction of posterior segment structures occurred in both groups after 6 days of therapy.

CONCLUSIONS

These data support trovafloxacin as a potential oral agent for treatment or prophylaxis of S epidermidis endophthalmitis, although retinal alterations that occur over the period required for vitreous sterilization suggest that it will not replace intravitreal therapy in established endophthalmitis.

Assessment of drug accumulation in the evaluation of pharmacokinetic data

The evaluation of drug accumulation is approached from a practical point of view. Estimates of accumulation indices as obtained from standard estimators-AUC, peak levels, and trough levels (RAUAUC Rmax and Rmin, respectively)-are compared and differences analyzed. The estimators are based on the concentration-time curve characteristics area under the concentration-time curve (AUC), maximum concentration, and trough level. Simulated data are used for the analysis, both noise-free and with random error added. The data are based on pharmacokinetic parameters derived from a clinical study. The numerical procedures can be reproduced by the interested reader with little effort. It is shown empirically that if Rmin, > RAUC then simple kinetic behavior cannot be safely assumed, but accumulation is a complex function of time. Rmax as obtained from the data and an estimate of this value based on time to peak concentration (tmax) and apparent elimination rate constant (lambda(z)) after a single dose and at steady state can then be compared in an attempt to exclude time-dependent kinetics. This new numerical procedure can provide valuable and even pivotal information regarding the accumulation kinetics of a compound under investigation. Recommendations on how to use the available concentration-time information to the best advantage are presented. It is concluded that the assessment of drug accumulation should not be confined to the calculation of just one estimate, because the three estimators RAUC, Rmax. and Rmin reflect different aspects of accumulation. Moreover, all information about accumulation should be carefully analyzed in the clinical context. This way the relevant accumulation can be identified for safe and efficacious drug treatment.

Pharmacokinetics of [18F]trovafloxacin in healthy human subjects studied with positron emission tomography

Tissue pharmacokinetics of trovafloxacin, a new broad-spectrum fluoroquinolone antimicrobial agent, were measured by positron emission tomography (PET) with [18F]trovafloxacin in 16 healthy volunteers (12 men and 4 women). Each subject received a single oral dose of trovafloxacin (200 mg) daily beginning 5 to 8 days before the PET measurements. Approximately 2 h after the final oral dose, the subject was positioned in the gantry of the PET camera, and 1 h later 10 to 20 mCi of [18F]trovafloxacin was infused intravenously over 1 to 2 min. Serial PET images and blood samples were collected for 6 to 8 h, starting at the initiation of the infusion. Drug concentrations were expressed as the percentage of injected dose per gram, and absolute concentrations were estimated by assuming complete absorption of the final oral dose. In most tissues, there was rapid accumulation of the radiolabeled drug, with high levels achieved within 10 min after tracer infusion. Peak concentrations of more than five times the MIC at which 90% of the isolates are inhibited (MIC90) for most members of Enterobacteriaceae and anaerobes (>10-fold for most organisms) were achieved in virtually all tissues, and the concentrations remained above this level for more than 6 to 8 h. Particularly high peak concentrations (micrograms per gram; mean +/- standard error of the mean [SEM]) were achieved in the liver (35.06 +/- 5.89), pancreas (32.36 +/- 20. 18), kidney (27.20 +/- 10.68), lung (22.51 +/- 7.11), and spleen (21. 77 +/- 11.33). Plateau concentrations (measured at 2 to 8 h; micrograms per gram; mean +/- SEM) were 3.25 +/- 0.43 in the myocardium, 7.23 +/- 0.95 in the lung, 11.29 +/- 0.75 in the liver, 9.50 +/- 2.72 in the pancreas, 4.74 +/- 0.54 in the spleen, 1.32 +/- 0.09 in the bowel, 4.42 +/- 0.32 in the kidney, 1.51 +/- 0.15 in the bone, 2.46 +/- 0.17 in the muscle, 4.94 +/- 1.17 in the prostate, and 3.27 +/- 0.49 in the uterus. In the brain, the concentrations (peak, approximately 2.63 +/- 1.49 microg/g; plateau, approximately 0.91 +/- 0.15 microg/g) exceeded the MIC90s for such common causes of central nervous system infections as Streptococcus pneumoniae (MIC90, <0.2 microg/ml), Neisseria meningitidis (MIC90, <0.008 microg/ml), and Haemophilus influenzae (MIC90, <0.03 microg/ml). These PET results suggest that trovafloxacin will be useful in the treatment of a broad range of infections at diverse anatomic sites.

Treatment of acute exacerbations of chronic bronchitis: comparison of trovafloxacin and amoxicillin in a multicentre, double-blind, double-dummy study. Trovafloxacin Bronchitis Study Group

The efficacy and safety of trovafloxacin and amoxicillin were compared in a double-blind, double-dummy multicentre trial involving 412 patients (> or = 40 years of age) with acute exacerbations of chronic bronchitis (AECBs). Patients were randomized to 5 days' oral treatment with 200 or 100 mg trovafloxacin administered once daily, or 500 mg amoxicillin given three times daily. Overall clinical efficacy at the end of therapy was similar in each treatment group, with clinical success (cure+improvement) achieved in 88% and 91% of clinically evaluable patients receiving trovafloxacin 200 mg and 100 mg, respectively, and in 89% of amoxicillin-treated patients. Corresponding rates at follow-up were 77%, 85% and 79%, respectively. Similar responses were noted at the end of treatment and end of study in the intent-to-treat patients. Although all three treatments produced similar bacteriological efficacy, there was a trend towards higher eradication rates for Haemophilus influenzae among patients (both clinically evaluable and intent-to-treat populations) treated with trovafloxacin 200 mg compared with those treated with amoxicillin. Both drugs were well tolerated, with treatment-related adverse events, of which headache and gastrointestinal disturbances were the most common, occurring in 12% and 6% of patients in the trovafloxacin 200 mg and 100 mg groups, respectively, and in 9% of amoxicillin-treated patients.

A comparative study on the efficacy of the new quinolone alatrofloxacin in the treatment of experimental legionellosis in guinea pigs

The in vivo efficacy of trovafloxacin, intraperitoneally administered as alatrofloxacin (CP-116,517), was assessed and compared with that of erythromycin, alone or in combination with rifampicin, in a model of Legionella pneumophila pneumonia in guinea pigs. Trovafloxacin (5 mg/kg administered as alatrofloxacin once daily for 7 days) gave a survival rate of 100% in infected animals. Clearance of bacteria and of bacteria-induced lesions from lungs was achieved by day 6 post-inoculation. The lungs of trovafloxacin-treated animals remained free of bacteria at day 28 post-challenge. Trovafloxacin proved as effective as erythromycin administered intraperitoneally, but was superior to erythromycin alone. or in combination with rifampicin, when given orally.

Trovafloxacin versus amoxicillin/clavulanic acid in the treatment of acute exacerbations of chronic obstructive bronchitis

Treatments with once-daily trovafloxacin (200 or 100 mg) and amoxicillin/clavulanic acid (500/125 mg three times daily) were compared in adults with acute exacerbations of chronic obstructive bronchitis. At end of treatment, 95% (113/119) of clinically evaluable patients receiving trovafloxacin 200 mg, 98% (113/115) of patients treated with trovafloxacin 100 mg and 97% (113/117) of patients receiving amoxicillin/clavulanic acid were cured or improved. At study end, 91%, 87% and 88%, respectively, were cured or improved. At end of treatment, trovafloxacin 200 mg eradicated Haemophilus influenzae in 97% of patients, Streptococcus pneumoniae in 90% and Chlamydia pneumoniae in 100%. The respective eradication rates for trovafloxacin 100 mg were 84%, 100% and 100%; those for amoxicillin/clavulanic acid were 92%, 100% and 100%. At study end, trovafloxacin 200 mg totally eradicated all three pathogens. Trovafloxacin 100 mg eradicated Haemophilus influenzae in 91% of patients, Streptococcus pneumoniae in 100% and Chlamydia pneumoniae in 80%. Respective eradication rates for amoxicillin/clavulanic acid were 78%, 100% and 80%. Only 7% (10/144) of patients receiving trovafloxacin 200 mg reported treatment-related adverse events, as did 7% (10/135) of patients given trovafloxacin 100 mg and 12% (17/140) of patients given amoxicillin/clavulanic acid.

Efficacy of trovafloxacin against experimental Staphylococcus aureus endocarditis

Trovafloxacin is a new fluoronaphthyridone chemically and functionally related to members of the fluoroquinolone class of antimicrobial agents. The in vivo efficacy of the drug was compared with that of vancomycin by using the rabbit model of left-sided endocarditis. Rabbits infected with either a nafcillin-susceptible or -resistant test strain were treated with trovafloxacin (13.3 mg/kg of body weight every 12 h) or vancomycin (25 mg/kg of body weight every 8 h) for 4 days. In comparison with untreated controls, both antimicrobial agents effectively cleared bacteremia and significantly reduced bacterial counts in vegetations and tissues of animals infected with either test strain. No resistance to trovafloxacin emerged in test strains during therapy. We conclude that in this model trovafloxacin is as efficacious as vancomycin is and may serve as a viable alternative to vancomycin for use in humans with similar infections.

Pharmacokinetics of grepafloxacin after oral administration of single and repeat doses in healthy young males

The pharmacokinetics of grepafloxacin in healthy male subjects following single oral administration of doses ranging from 200 to 1200 mg, and following repeated oral administration of 400 and 800 mg doses are reported. Plasma levels of grepafloxacin reached a peak within 2 hours (on average) following drug administration and then declined bi-exponentially with concentrations being detectable (> 5 micrograms/L) in the plasma for at least up to 72 hours postdose. The high values for the apparent volume of distribution (5 to 8 L/kg) suggested extensive distribution of grepafloxacin in the tissues. Only a small percentage of the administered dose (ranging from 6% to 9.5%) was recovered in the urine as unchanged grepafloxacin, suggesting that metabolism, rather than urinary excretion, is the major elimination route. The half-life of grepafloxacin was about 12 hours after single doses and about 15 hours after repeat doses. The trough levels increased significantly over the first 3 days of repeat administration; thereafter, the changes were small, with steady-state being reached by the fifth day. The area under the concentration-time curve (AUC24 h) values observed on days 7 and 14 of repeat administration, at each dose level, were similar, suggesting that steady-state is maintained. The area values increased more than proportionally after administration of increasing single and repeat doses, suggesting nonlinear kinetics. The elimination half-life and renal clearance did not change with increasing doses. Saturation in the metabolism of grepafloxacin and possibly in the distribution into a peripheral compartment, as suggested by a decrease in the total plasma clearance and in the apparent volume of distribution, could be the origin of the nonlinear kinetics. However, this deviation from linearity is unlikely to be of clinical significance, since it was very small over the recommended range of therapeutic doses (400 to 600 mg once daily). Compared with other quinolones, grepafloxacin showed the longest half-life and the highest apparent volume of distribution. These features, together with the excellent bactericidal activity of grepafloxacin, support the recommended dosage regimen of grepafloxacin for the treatment of respiratory tract infections and sexually transmitted diseases.