Pharmacokinetics and metabolism of single oral doses of trovafloxacin

Microfluidic human physiomimetic liver model as a screening platform for drug induced liver injury

The pre-clinical animal models often fail to predict intrinsic and idiosyncratic drug induced liver injury (DILI), thus contributing to drug failures in clinical trials, black box warnings and withdrawal of marketed drugs. This suggests a critical need for human-relevant in vitro models to predict diverse DILI phenotypes. In this study, a porcine liver extracellular matrix (ECM) based biomaterial ink with high printing fidelity, biocompatibility and tunable rheological and mechanical properties is formulated for supporting both parenchymal and non-parenchymal cells. Further, we applied 3D printing and microfluidic technology to bioengineer a human physiomimetic liver acinus model (HPLAM), recapitulating the radial hepatic cord-like structure with functional sinusoidal microvasculature network, biochemical and biophysical properties of native liver acinus. Intriguingly, the human derived hepatic cells incorporated HPLAM cultured under physiologically relevant microenvironment, acts as metabolic biofactories manifesting enhanced hepatic functionality, secretome levels and biomarkers expression over several weeks. We also report that the matured HPLAM reproduces dose- and time-dependent hepatotoxic response of human clinical relevance to drugs typically recognized for inducing diverse DILI phenotypes as compared to conventional static culture. Overall, the developed HPLAM emulates in vivo like functions and may provide a useful platform for DILI risk assessment to better determine safety and human risk.

Evaluation of drug-induced liver toxicity of trovafloxacin and levofloxacin in a human microphysiological liver model

Drug-induced liver injury induced by already approved substances is a major threat to human patients, potentially resulting in drug withdrawal and substantial loss of financial resources in the pharmaceutical industry. Trovafloxacin, a broad-spectrum fluoroquinolone, was found to have unexpected side effects of severe hepatotoxicity, which was not detected by preclinical testing. To address the limitations of current drug testing strategies mainly involving 2D cell cultures and animal testing, a three-dimensional microphysiological model of the human liver containing expandable human liver sinusoidal endothelial cells, monocyte-derived macrophages and differentiated HepaRG cells was utilized to investigate the toxicity of trovafloxacin and compared it to the structurally-related non-toxic drug levofloxacin. In the model, trovafloxacin elicited vascular and hepatocellular toxicity associated with pro-inflammatory cytokine release already at clinically relevant concentrations, whereas levofloxacin did not provoke tissue injury. Similar to in vivo, cytokine secretion was dependent on a multicellular immune response, highlighting the potential of the complex microphysiological liver model for reliably detecting drug-related cytotoxicity in preclinical testing. Moreover, hepatic glutathione depletion and mitochondrial ROS formation were elucidated as intrinsic toxicity mechanisms contributing to trovafloxacin toxicity.

Transporter and metabolizer gene polymorphisms affect fluoroquinolone pharmacokinetic parameters

Tuberculosis (TB) is an infectious disease that occurs globally. Treatment of TB has been hindered by problems with multidrug-resistant strains (MDR-TB). Fluoroquinolones are one of the main drugs used for the treatment of MDR-TB. The success of therapy can be influenced by genetic factors and their impact on pharmacokinetic parameters. This review was conducted by searching the PubMed database with keywords polymorphism and fluoroquinolones. The presence of gene polymorphisms, including UGT1A1, UGT1A9, SLCO1B1, and ABCB1, can affect fluoroquinolones pharmacokinetic parameters such as area under the curve (AUC), creatinine clearance (C_Cr), maximum plasma concentration (C_max), half-life (t_1/2) and peak time (t_max) of fluoroquinolones.

Influence of Liver Extracellular Matrix in Predicting Drug-Induced Liver Injury: An Alternate Paradigm

In vitro drug-induced liver injury (DILI) models are promising tools for drug development to predict adverse events during clinical usage. However, the currently available DILI models are not specific or not able to predict the injury accurately. This is believed to be mainly because of failure to conserve the hepatocyte phenotype, lack of longevity, and difficulty in maintaining the tissue-specific microenvironment. In this study, we have assessed the potential of decellularized liver extracellular matrix (DLM) in retaining the hepatic cellular phenotype and functionality in the presence of a tissue-specific microenvironment along with its role in influencing the effect of the drug on hepatic cells. We show that DLM helps maintain the phenotype of the hepatic cell line HepG2, a well-known cell line for secretion of human proteins that is easily available. Also, the DLM enhanced the expression of a metabolic marker carbamoyl phosphate synthetase I (CPS1), a regulator of urea cycle, and bile salt export pump (BSEP), a marker of hepatocyte polarity. We further validated the DLM for its influence on the sensitivity of cells toward different classes of drugs. Interestingly, the coculture model, in the presence of endothelial cells and stellate cells, exhibited a higher sensitivity for both acetaminophen and trovafloxacin, a toxic compound that does not show any toxicity on preclinical screening. Thus, our results demonstrate for the first time that a multicellular combination along with DLM can be a potential and reliable DILI model to screen multiple drugs.

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.

Trovafloxacin-Induced Liver Injury: Lack in Regulation of Inflammation by Inhibition of Nucleotide Release and Neutrophil Movement

The fluoroquinolone trovafloxacin (TVX) is associated with a high risk of drug-induced liver injury (DILI). Although part of the liver damage by TVX+TNF relies on neutrophils, we have recently demonstrated that liver recruitment of monocytes and neutrophils is delayed by TVX. Here we show that the delayed leukocyte recruitment is caused by a combination of effects which are linked to the capacity of TVX to block the hemichannel pannexin 1. TVX inhibited find-me signal release in apoptotic HepG2 hepatocytes, decelerated freshly isolated human neutrophils toward IL-8 and f-MLF, and decreased the liver expression of ICAM-1. In blood of TVX+TNF-treated mice, we observed an accumulation of activated neutrophils despite an increased MIP-2 release by the liver. Depletion of monocytes and neutrophils caused increased serum concentrations of TNF, IL-6, and MIP-2 in TVX-treated mice as well as in mice treated with the fluoroquinolone levofloxacin, known to have a lower DILI-inducing profile. This supports the idea that early leukocyte recruitment regulates inflammation. In conclusion, disrupted regulation by leukocytes appears to constitute a fundamental step in the onset of TVX-induced liver injury, acting in concert with the capability of TVX to induce hepatocyte cell death. Interference of leukocyte-mediated regulation of inflammation represents a novel mechanism to explain the onset of DILI.

Identification of metabolites of novel Anti-MRSA fluoroquinolone WCK 771 in mouse, rat, rabbit, dog, monkey and human urine using liquid chromatography tandem mass spectrometry

WCK 771 is an l-arginine salt of levonadifloxacin (LND) being developed in intravenous dosage form and has recently completed a phase III trial in India. The pharmacokinetics of WCK 771, a novel anti-MRSA fluoroquinolone, were examined in mice, rats, rabbits, dogs, monkeys and humans after systemic administration during pre-clinical and clinical investigations. Urine and serum were evaluated for identification of metabolites. It was observed that LND mainly follows phase II biotransformation pathways. All of the species showed a different array of metabolites. In mice, rabbit and dog, the drug was mainly excreted in the form of O-glucuronide (M7) and acyl glucuronide (M8) conjugates, whereas in rat and human major metabolite was sulfate conjugate (M6). Monkeys exhibited equal distribution of sulfate (M6) and glucuronide conjugates (M7, M8). In addition to these three major phase II metabolites; five phase I oxidative metabolites (M1, M2, M3, M4 and M5) were identified using liquid chromatography tandem mass spectrometry. Out of these eight metabolites M2, M3, M5, M7 and M8 are reported for the first time.

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.

A 3D in vitro model of differentiated HepG2 cell spheroids with improved liver-like properties for repeated dose high-throughput toxicity studies

Immortalized hepatocyte cell lines show only a weak resemblance to primary hepatocytes in terms of gene expression and function, limiting their value in predicting drug-induced liver injury (DILI). Furthermore, primary hepatocytes cultured on two-dimensional tissue culture plastic surfaces rapidly dedifferentiate losing their hepatocyte functions and metabolic competence. We have developed a three-dimensional in vitro model using extracellular matrix-based hydrogel for long-term culture of the human hepatoma cell line HepG2. HepG2 cells cultured in this model stop proliferating, self-organize and differentiate to form multiple polarized spheroids. These spheroids re-acquire lost hepatocyte functions such as storage of glycogen, transport of bile salts and the formation of structures resembling bile canaliculi. HepG2 spheroids also show increased expression of albumin, urea, xenobiotic transcription factors, phase I and II drug metabolism enzymes and transporters. Consistent with this, cytochrome P450-mediated metabolism is significantly higher in HepG2 spheroids compared to monolayer cultures. This highly differentiated phenotype can be maintained in 384-well microtiter plates for at least 28 days. Toxicity assessment studies with this model showed an increased sensitivity in identifying hepatotoxic compounds with repeated dosing regimens. This simple and robust high-throughput-compatible methodology may have potential for use in toxicity screening assays and mechanistic studies and may represent an alternative to animal models for studying DILI.

Effects of substituents on the NMR features of basic bicyclic ring systems of fluoroquinolone antibiotics and the relationships between NMR chemical shifts, molecular descriptors and drug-likeness parameters

In the present study, the NMR spectroscopic features of trovafloxacin (TVA) mesylate, pefloxacin (PFX) mesylate dihydrate and ciprofloxacin (CIP) hydrochloride monohydrate were studied in DMSO-d6 solution with the aim of investigating the effects of substituents and the type of salt on the NMR parameters of basic bicyclic fluoroquinolone and fluoronaphthyridone ring systems. For this purpose, the 1H- and 13C- one- and two-dimensional homo- and heteronuclear NMR methods were used. The analysis of 1H- and 13C-NMR spectra confirmed the structures of investigated fluoroquinolone salts. Relationships between 1H- and 13C-NMR chemical shifts of fluoronaphthyridone and fluoroquinolone ring systems, calculated molecular descriptors (MDs) and drug-likeness scores (DLSs), computed for monoprotonic cations of investigated fluoroquinolone salts (TVAH+, PFXH+ and CIPH+), were also explored. The topological polar surface area (TPSA), the parameter of lipophilicity (miLogP), the relative molecular mass (Mr) and the volume (V) of computed molecular descriptors (MDs), as well as the G protein-coupled receptor ligand-likeness (GPCR ligand-ls), the ion channel ligand-likeness (ICL-ls), the kinase inhibitor-likeness (KI-ls) and the nuclear receptor ligand-likeness (NRL-ls) were used in this study. The 1H-NMR chemical shifts of protons in COOH, H5 and NHn+, as well as 13C-NMR chemical shifts of C4, C5 and C11 shown to be good parameters in exploration of property-property and property-drug-likeness relationships for investigated fluoroquinolone salts. Thus, collinear relationships of 1H-NMR chemical shifts of protons in COOH, H5 and NHn+ with TPSA and miLogP, as well as with GPCR ligand-ls, KI-ls and NRL-ls were revealed (δ, ppm H in COOH vs. TPSA, R = -0.9421; δ, ppm H in COOH vs. NRL-ls, R = -0.9216; δ, ppm H5 vs. miLogP, R = 0.9962; δ, ppm H5 vs. KI-ls, R = 0.9969; δ, ppm NHn+vs. TPSA, R = -0.9875 and δ, ppm NHn+vs. NRL-ls, R = -0.9948). The collinearities between, 13C-NMR chemical shifts of C4, C5 and C11 with KI-ls and NRL-ls, as well as with TPSA, miLogP, Mr and V were also revealed (δ, ppm C4 vs. TPSA, R = 0.9964; δ, ppm C4 vs. miLogP, R = 0.9487; δ, ppm C4 vs.Mr, R = 0.9629; δ, ppm C4 vs. KI-ls, R = 0.9461; δ, ppm C4 vs. NRL-ls, R = 0.9996; δ, ppm C5 vs. miLogP, R = 0.9994; δ, ppm C5 vs. KI-ls, R = 0.9990; δ, ppm C5 vs. NRL-ls, R = 0.9510; δ, ppm C11 vs. TPSA, R = -0,9958; δ, ppm C11 vs. NRL-ls, R = -0.9994 and δ, ppm C11 vs. KI-ls, R = -0.9481).

Methods to evaluate biliary excretion of drugs in humans: an updated review

Determining the biliary clearance of drugs in humans is very challenging because bile is not readily accessible due to the anatomy of the hepatobiliary tract. The collection of bile usually is limited to postsurgical patients with underlying hepatobiliary disease. In healthy subjects, feces typically are used as a surrogate to quantify the amount of drug excreted via nonurinary pathways. Nevertheless, it is very important to characterize hepatobiliary elimination because this is a potential site of drug interactions that might result in significant alterations in systemic or hepatic exposure. In addition to the determination of in vivo biliary clearance values of drugs, the availability of in vitro models that can predict the extent of biliary excretion of drugs in humans may be a powerful tool in the preclinical stages of drug development. In this review, recent advances in the most commonly used in vivo methods to estimate biliary excretion of drugs in humans are outlined. Additionally, in vitro models that can be employed to investigate the molecular processes involved in biliary excretion are discussed to present an updated picture of the new tools and techniques that are available to study the complex processes involved in hepatic drug transport.

Effect of cirrhosis on antibiotic efficacy in a rat model of pneumococcal pneumonia

A rat model was used to study the effects of cirrhosis on antibiotic therapy of pneumococcal pneumonia. Cirrhotic and control male Sprague-Dawley rats were infected transtracheally with type 3 Streptococcus pneumoniae. Treatment began 18 h later with phosphate-buffered saline (PBS), azithromycin (50 mg/kg), trovafloxacin (50 mg/kg), or ceftriaxone (100 mg/kg) injected subcutaneously twice daily for 5 days. Antibiotic concentrations were measured by high-performance liquid chromatography. Azithromycin, trovafloxacin, and ceftriaxone were all equally effective at preventing mortality in both cirrhotic and normal rats. Free fraction area under the curve to minimum inhibitory concentration ratio (AUC/MIC) and maximum calculated serum concentration to MIC ratio (C(max)/MIC) and percent time that the serum concentration exceeded the MIC (%T > MIC) were greater for ceftriaxone compared with azithromycin or trovafloxacin. Azithromycin achieved higher concentrations in bronchoalveolar lavage fluid (BALF), epithelial lining fluid (ELF), and BAL white blood cells than ceftriaxone or trovafloxacin in cirrhotic rats. Macrolide, beta-lactam, or fluoroquinolone antibiotic efficacy in a pneumococcal pneumonia model does not appear to be affected by hepatic cirrhosis.

Determination of the antibacterial trovafloxacin by differential-pulse adsorptive stripping voltammetry

A differential-pulse adsorptive stripping voltammetric method for the determination of trace amounts of the antibacterial trovafloxacin (TRFLX) is proposed. The optimal experimental parameters for the drug assay were: accumulation potential=-0.30 V (vs. Ag/AgCl), accumulation time=120 s, pulse amplitude=50 mV and scan rate=5 mV s(-1) in Britton-Robinson buffer (pH 4.5). The linear concentration range of application was 2.0-20.0 ng ml(-1) of TRFLX, with a relative standard deviation of 3.6% (for a level of 5.0 ng ml(-1)) and a detection limit of 0.6 ng ml(-1). The method was applied to determination of TRFLX in human urine and serum samples. It was validated using HPLC as a reference method. Recovery levels of the method reached 100% in all cases

Determination of trovafloxacin in human serum by time resolved terbium-sensitised luminescence

A sensitive time-resolved luminescence method for the determination of trovafloxacin is described. The method is based on the time-resolved luminescence signal from the terbium(III)-trovafloxacin complex, in a micellar solution of sodium dodecyl sulfate (SDS), using a chemical deoxygenation agent (Na(2)SO(3)). The method allows the determination of 20-450 ng ml(-1) of trovafloxacin in 7.5 mM SDS solution containing 0.16 M acetic acid-sodium acetate buffer (pH 6.0) and 7.5 mM Na(2)SO(3) with lambda(exc)=270 nm and lambda(em)=546 nm. In these experimental conditions luminescence signal for trovafloxacin increases 20-fold with respect to native fluorescence of the compound in aqueous solution at pH 6.5. Terbium-sensitised luminescence was applied to trovafloxacin determination in human serum, spiked at levels found after drug administration at normal clinical doses. Recovery is 90+/-1% and day-to-day precision is 3.5%. The proposed method tolerates high concentrations of other co-administrated drugs and excipients.

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.