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.

Effect of silver nanoparticles on the antibacterial activity of Levofloxacin against methicillin-resistant Staphylococcus aureus.

OBJECTIVE: The paper presents the antibacterial activity of silver nanoparticles (AgNPs) when conjugated with Levofloxacin. The AgNPs used in this study were synthesized from silver nitrate using sodium borohydride as a reducing agent. MATERIALS AND METHODS: Levofloxacin activity was determined by minimum inhibitory concentrations (MICs) and also the erythrocyte hemolytic assay determined the capability of conjugation to cause hemolysis in human erythrocyte. RESULTS: The synthesis of levofloxacin-AgNP conjugates was confirmed by ultraviolet/visible (UV/vis) spectroscopy. A peak absorption value between 400-450 nm for the extract and the color change to dark brown were corresponding to the plasmon absorbance of AgNPs. On the other hand, levofloxacin-AgNPs could be effective against methicillin-resistant Staphylococcus aureus (MRSA). The MICs of levofloxacin and levofloxacin-AgNPs were 12 and 10 µM, respectively. CONCLUSIONS: These findings indicated that levofloxacin-AgNPs had an effective bactericidal activity against the bacterial MRSAs. This conjugation appeared to inhibit bacterial adaptive capabilities, which leads to inhibition of bacterial resistance.

Novel Insights on MRGPRX2-Mediated Hypersensitivity to Neuromuscular Blocking Agents And Fluoroquinolones.

Neuromuscular blocking agents (NMBAs) like atracurium and rocuronium as well as fluoroquinolones (FQs) cause mast cell-mediated anaphylaxis by activating Mas-related G protein-coupled receptor X2 (MRGPRX2), but many questions remain unanswered. Here, we address three of them, namely whether primary human mast cells show similar activation by these drugs as murine mast cells and mast cell lines, how sugammadex protects from atracurium-induced MRGPRX2-mediated mast cell activation, and why some but not all patients treated with rocuronium develop anaphylaxis. We used peripheral blood-derived cultured mast cells from healthy donors and patients, assessed mast cell activation and degranulation by quantifying intracellular calcium and CD63 expression, respectively, and made use of MRGPRX2-silencing, via electroporation with Dicer-substrate small interfering RNAs, and single cell flow cytometric analyses. Atracurium, ciprofloxacin, and levofloxacin activated and degranulated primary human mast cells, but only MRGPRX2-positive and not MRGPRX2-negative or -silenced mast cells. Sugammadex attenuated the atracurium-induced and MRGPRX2-mediated activation and degranulation of human mast cells by reducing free atracurium levels. The mast cells of patients with IgE-independent anaphylaxis to rocuronium were similar, in their MRGPRX2 expression and function, to those of patients with IgE-mediated anaphylaxis. These findings further improve our understanding of the role and relevance of MRGPRX2-driven mast cell activation in anaphylactic reactions to NMBAs and FQs and may help to improve their prediction, prevention, and treatment.

Bioassay- and QSAR-based screening of toxic transformation products and their formation under chlorination treatment on levofloxacin.

Levofloxacin (LEV) is a broad-spectrum quinolone antibiotic and widely used for human and veterinary treatment. Overuse of LEV leads to its frequent occurrence in the water environment. In this study, the transformation characteristics of LEV in water during the simulated chlorination disinfection treatment were explored. Fifteen major transformation products (TPs) of LEV were identified, and their plausible formation pathways were proposed. The reaction pathways were strongly dependent on pH condition, and LEV removal was relevant to free available chlorine (FAC) dose. Antibacterial activity of chlorination system was dramatically declined when FAC was more than 3-equivalent (eq) due to the elimination of antibacterial related functional groups. Genotoxicity of chlorination system increased more than 3 times at 0.5-eq of FAC and then decreased with increasing FAC dose, which were in accordance with the relative concentration of toxic TPs estimated by QSAR model. These results implied that the combination of bioassay, QSAR computation and chemical analysis would be an efficient method to screen toxic TPs under chlorination treatment. It is anticipated that the results of this study can provide reference for optimizing operational parameters for water disinfection treatment, and for scientifically evaluating the potential risk of quinolone antibiotics.

In vitro and in vivo evaluation of clastogenicity of second-line antitubercular drug loaded PLGA nanoparticles.

Sustained release nanoformulations of second line antitubercular drugs levofloxacin and ethionamide had shown promise in pharmacokinetics and acute and sub-acute toxicity studies. The present study evaluated the clastogenicity potential of the nanoformulations of these antitubercular agents. Clastogenicity was evaluated by (a) in vitro micronucleus assay (b) in vivo micronucleus assay in Swiss albino mice and (c) sister chromatid exchange (SCE) in CHO cell lines. Ethionamide and levofloxacin loaded nanoparticles were 312 ± 64 nm and 245 ± 24 nm in size respectively and drug encapsulation was 35.2 ± 3.1% w/w and 45.6 ± 9.4% w/w, respectively. The frequency of MN-NCE/1000 NCE and MN-PCE/1000 PCE were significantly reduced in mice treated with ethionamide nanoparticle (3.5 ± 0.9, 13.8 ± 16.68) and levofloxacin nanoparticles (5.6 ± 2.7, 16.7 ± 12.7) compared to the mice treated with free ethionamide (11.5 ± 4.1, p = 0.23 and 45.19 ± 19.21, p = 0.38) and free levofloxacin (14.7 ± 1.88, p < 0.0001 and 54.6 ± 18.1, p = 0.0017), respectively. For in vitro, micronucleus assay frequencies of micronuclei per thousand bi-nucleated cells (MN-BN/1000 BN) was 188.3 ± 20.20 and 148 ± 20.42 for ethionamide and levofloxacin nanoparticles as compared to 232.6 ± 16.04 (p = 0.52) and 175 ± 5.56 (p = 0.45) for free ethionamide and levofloxacin, respectively. The average number of SCE per cell for nanoformulation of ethionamide were not different from that of free drug (4.9 ± 0.51 vs 4.1 ± 0.55, p = 0.86). The SCE per cells were not significant difference for nanoformulation of levofloxacin (2.33 ± 1.36 vs 5.46 ± 0.25, p = 0.88). In vitro and in vivo assays have shown relatively less clastogenic potential of equivalent dose of ethionamide nanoparticles as compared to the conventional formulation.

Levofloxacin and sulfamethoxazole induced alterations of biomolecules in Pseudokirchneriella subcapitata.

Levofloxacin (LEV) and sulfamethoxazole (SMX) are two extensively used antibiotics. Most investigations have been concentrated on the toxic effects of antibiotics on algal species evaluated with traditional ecotoxicological endpoints; however, limited information is available on the alterations in biomolecules induced by antibiotics. Here we investigated alterations in the structure and function of biomolecules to a model species Pseudokirchneriella subcapitata following exposure of LEV and SMX by applying Fourier transform infrared spectroscopy (FTIR). The growth inhibition tests revealed that both LEV and SMX had negative effects on algal growth, while SMX was found to be more toxic to P. subcapitata than LEV. Based on the FTIR analysis, alterations in the structure, composition and function of lipids and proteins were observed on microalgal cells, which were correlated with the dosage of LEV and SMX. As a result of lipid peroxidation induced by LEV and SMX, an increase in the lipid/protein ratio and decrease in the ratios of CH2/lipid, CH3/lipid, carbonyl ester/lipid and olefinic = CH/lipid were observed in all treatment groups with respect to the reference control. Moreover, alterations in the composition and secondary structure of proteins were also observed in accompany with a decrease in the Amide I/Amide II ratio and an increase of the loose ß-sheet structure protein. LEV caused an elevated level of lipid peroxidation, while SMX induced a more obvious protein aggregation. The findings from this study showed that FTIR could reveal the toxic mechanism of these two antibiotics to algae at the biochemical level by linking alterations in biomolecules to biochemical dynamics and function.

Preparation of levofloxacin loaded in situ gel for sustained ocular delivery: in vitro and ex vivo evaluations.

The major drawback of the eye drops is rapid elimination of drug from the precorneal region, thus ensuing poor bioavailability as well as therapeutic efficacy. To conquer these limitations, a pH triggered in situ gel was developed for sustained delivery of levofloxacin. Two polymers namely hydroxypropyl methylcellulose (HPMC) and sodium alginate along with the boric acid buffer were used to formulate the in situ gel. Based on the various physicochemical evaluation parameters like pH, clarity and gelling capacity placebo formulations were selected and further characterized for viscosity, in vitro release, ex vivo corneal permeation, and histopathological studies. The optimized in situ gel (F28) showed sustained release of 93 ± 4.23% for 24 h and cumulative drug permeation of 71.81 ± 4.7% for 72 h. Additionally, ocular irritation study and histopathology of the formulation treated cornea confirm the non-irritancy of the optimized formulation. Based on all the above performed studies, it can be concluded that the in situ gel would present a fruitful alternative for the ocular infections.

Antibiotic-Based Conjugates Containing Antimicrobial HLopt2 Peptide: Design, Synthesis, Antimicrobial and Cytotoxic Activities.

Recent studies have shown that modified human lactoferrin 20-31 fragment, named HLopt2, possesses antibacterial and antifungal activity. Thus, we decided to synthesize and evaluate the biological activity of a series of conjugates based on this peptide and one of the antimicrobials with proven antibacterial (ciprofloxacin, CIP, and levofloxacin, LVX) or antifungal (fluconazole, FLC) activity. The drugs were covalently connected to the peptide via amide, methylenecarbonyl moieties, or a disulfide bridge. The antibacterial and antifungal activities were evaluated under Clinical and Laboratory Standard Institute (CLSI) recommended conditions or in a low-salt brain-heart infusion diluted medium (BHI1/100). Results showed that conjugation of the peptide with the drug increased its antimicrobial activity up to 4-fold. Under CLSI-recommended conditions, all the compounds revealed rather low efficiency. Among conjugates, the highest antibacterial activity was recorded for the CIP-Cys-S-S-HLopt2-NH2 (III). In BHI1/100, which had lower differentiating properties, all of the conjugates revealed low MIC and MMC (minimum inhibitory and microbicidal concentrations) values. The disulfide bridge used as a linker in the most active conjugate (III) upon incubation with S. aureus cells is reduced, releasing constituent peptide and CIP-Cys. In addition, we showed that its fluorescently labeled analogue and constituent peptide are able to be internalized into both C. albicans and S. aureus cells. Moreover, the invaluable advantage of the presented conjugates was their low toxicity to mammalian cells and very low hemolytic activity. The current research can form a solid basis for further in vivo studies and drug development.

Effects of levofloxacin exposure on sequencing batch reactor (SBR) behavior and microbial community changes.

The adaptation mechanisms of bacterial community for nitrogen removal performance exposed to fluctuated levels of levofloxacin (LVX) during wastewater treatment in SBRs were investigated. Although LVX is completely synthetic, the results of minimum inhibitory concentration (MIC, 32 mg-LVX/L) and minimum bactericidal concentration (MBC, 512 mg-LVX/L) of the sampled sludge showed that the LVX resistance/tolerance for bacterial growth has already existed in the actual wastewater treatment plants (WWTPs). The key bacteria, i.e. Nitrosomonas sp. (ammonia-oxidizing bacteria), Nitrospira sp. (nitrite-oxidizing bacteria) and Thauera sp. (the predominant denitrifiers), decreased with LVX exposure, and the recovery of biological process in the reactor was disturbed due to LVX exposure. However, after stopping exposure their population was quickly increased and thus the performance was recovered. The results of the non-metric multidimensional scaling and microbial community by sequencing showed the LVX concentration was a crucial factor to the change of bacterial communities and controlled the quantitative evolution of the communities in our systems. This effect was more pronounced as the LVX concentration was higher. The results suggested the removal of residual antibiotics to accomplish under no effect concentration before biological treatment is important to suppress emerging and increasing of the antibiotic resistant bacteria in WWTPs.

Development of levofloxacin-loaded PLGA microspheres of suitable properties for sustained pulmonary release.

Aerosol antibiotics are an interesting alternative to oral or intravenous therapy in Cystic Fibrosis lung infections. Levofloxacin (LVX) inhaled solution is already an effective option. In this study, the aim was the development of LVX-loaded PLGA microspheres (MS) for pulmonary administration as a dry powder. MS were prepared, for the first time, by a modified double emulsion solvent evaporation method with premix membrane homogenization. Aqueous phases were saturated with LVX and a fatty acid (lauric acid) was added to avoid the drug escaping from the organic phase. MS were characterized in terms of size, drug content, morphology and in vitro release properties. X-ray diffraction, Fourier-transform infrared spectroscopy, differential and gravimetric thermal analysis, and cytotoxicity analyses were performed. Results showed this new method increased the drug loading while maintaining an adequate (∼5 µm) particle size and controlled release. Compared to a solution for inhalation, these properties combined with the dry-powder nature of these MS will improve patient compliance. The incorporation of lauric acid was not advantageous because the particle size was higher and no improvements concerning the sustained release occurred. LVX was molecularly dispersed in the matrix, or it was in amorphous state, as confirmed by the physico-chemical analyses. Calu-3 cell viability assays demonstrated no cytotoxicity for these MS, making them a promising system for LVX pulmonary delivery.

Levofloxacin is phytotoxic and modifies the protein profile of lupin seedlings.

The toxicity of levofloxacin to yellow lupin plants was evaluated in this study. Recommended indexes of plant (roots and shoots) growth were determined and new indexes were proposed which better characterise the phytotoxicity of levofloxacin. These were, in particular, the activity of antioxidative enzymes, the content of free radicals, as well as the root protein content and the root protein profile. The results showed that levofloxacin considerably affected EC50, measured as the activity of catalase in roots, and leaves (1.05 and 0.069 mM, respectively). The activity of peroxidase in the roots and the dry weight of seedlings were the least sensitive parameters (EC50 was 1.8 and 1.76 mM, respectively). Units of toxicity clearly showed that the activity of catalase is a better measure of toxicity for low concentrations of the drug, and it is a better index of plant physiological state than the morphological parameters of seedlings. Moreover, levofloxacin changed the location of free radicals and the protein profile in plants. The changes in location of reactive oxygen species in roots were an important symptom of the drug toxicity to lupin seedlings. Our results have shown that the toxicity of levofloxacin was manifested mainly by changes in the protein profile. The content of the glyceraldehyde-3-phosphate dehydrogenase, 14-3-3-like protein A, expansin-B3-like precursor, fructose-bisphosphate aldolase, lipoxygenase, nucleotide-binding subunit of vacuolar ATPase and pyruvate dehydrogenase were found to decrease. On the other hand, plant exposure to levofloxacin resulted in an increase in the content of enolase, protein LlR18A, class III chitinase, ascorbate peroxidase, aspartate aminotransferase, alcohol dehydrogenase 1, leghemoglobin reductase-like 17 and heat shock cognate protein 80-like.

Cardiotoxic effect of levofloxacin and ciprofloxacin in rats with/without acute myocardial infarction: Impact on cardiac rhythm and cardiac expression of Kv4.3, Kv1.2 and Nav1.5 channels.

Prolongation of QT interval is possible with fluoroquinolones, yet the underlying contributing factors have not been elucidated. Two widely used fluoroquinolone drugs were at the focus of this study in rats with/without acute myocardial dysfunction (AMI) induced by isoproterenol. The effects of levofloxacin and ciprofloxacin on the cardiac mRNA expression of rat Kv4.3, Kv1.2 and Nav1.5 mRNAs were determined. Administration of the two antibiotics produced dose-dependent changes in ECG parameters that were more prominent in rats with AMI than healthy rats; this was accompanied by elevations in serum lactate dehydrogenase and creatine kinase-MB. Histopathological examination indicated some loss of striations, edema and fibrotic changes in rats with AMI; however the two antibiotics did not further exacerbate the cardiac histopathology. mRNA expression of the ion channels was altered in rats with AMI and healthy rats. In conclusion, long-term administration of levofloxacin and ciprofloxacin produced deleterious effects on the ECG pattern of rats with/without AMI. The effect was generally baseline-dependent and therefore, rats with AMI showed greater ECG disturbances and increases in cardiac enzymes. Taken together, these data make it advisable to monitor patients with a history of acute AMI requiring treatment with these antibiotics until data from human studies are available.

Application of XCMS Online and toxicity bioassays to the study of transformation products of levofloxacin.

We studied the nature and antimicrobial activity of ozonolysis transformation products (OTPs) of levofloxacin (LEV), a frequently detected fluoroquinolone antimicrobial in environmental waters. Two bioassays, the Kirby-Bauer test and the broth microdilution assay, were used to measure changes in the antimicrobial activity of solutions at low LEV to O3 molar ratios (2:1, 2:3 and 1:3) compared to solutions without added O3 (LEV:O3 1:0). The Kirby-Bauer test was not sensitive enough to detect significant differences in the growth inhibition zones in samples LEV:O3 2:1 and LEV:O3 1:0; however, the broth microdilution assay showed that bacterial growth inhibition was significantly lower (P<0.001) in the solutions exposed to O3. Loss of antimicrobial activity in LEV:O3 2:1 solutions of (48±16)% was in agreement with the concentration decrease of LEV of (36±3)% in those same samples. A method of identification of OTPs using XCMS Online was applied to LEV:O3 2:1 and 1:0 samples and indicated the presence of an OTP of LEV of formula C18H20O5N3F, which was identified as LEV-N-oxide. The molecular structure of this compound was partially confirmed by tandem mass spectrometry experiments. This study showed that even at sub-optimal ozone doses, OTPs of higher antimicrobial activity than LEV were not formed.

Levofloxacin and indolicidin for combination antimicrobial therapy.

Despite the increasing need for antibiotics to fight infectious diseases, fewer new antibiotics are available on the market. Unfortunately, developing a new class of antibiotics is associated with high commercial risk. Therefore, modification or combination of existing antibiotics to improve their efficacy is a promising strategy. Herein, we conjugated the antibiotic, levofloxacin, with two peptides, i.e. an antimicrobial peptide indolicidin and a cell penetrating peptide (TAT). Glycolic acid and glycine linkers were used between levofloxacin and peptides. We developed an optimized condition for coupling of levofloxacin via its carboxylic group to glycolic acid using solid phase peptide synthesis (SPPS). Antibacterial and haemolytic assays were carried out on the conjugates and only the levofloxacin-indolicidin conjugate demonstrated moderate antibacterial activity. Interestingly, physical mixture of levofloxacin and indolicidin showed improvement in the activity against Gram-positive bacteria.

Oxidative transformation of levofloxacin by δ-MnO2: products, pathways and toxicity assessment.

The characteristics of the oxidative transformation of the antibiotic levofloxacin (abbreviated as LEV) by manganese oxide were investigated. Up to 91% of LEV were removed with an equivalent of 200 units (abbreviated as equiv) of manganese oxide within a 35-day treatment period. A total of ten transformation products were identified, and five of them were newly reported. A tentative transformation pathway of LEV in the manganese oxide system involving oxidation and dealkylation was proposed. In addition, the variation in the genotoxicity and antibacterial activity along with the treatment by manganese oxide were traced using a SOS/umu assay and Escherichia coli growth inhibition assay, respectively. The results indicated that the genotoxicity significantly decreased in response to treatment with manganese oxide, while the antibacterial activity was not markedly affected until 160-equiv of δ-MnO2 were added. This study suggests that the oxidative degradation of LEV by manganese oxide can play an important role in the natural attenuation of LEV in sediment or soil matrices. The transformation reaction may be further optimized for removing quinolone antibiotics from wastewater or other environmental matrices to reduce the potential risk.

Toxic effects of levofloxacin on rat annulus fibrosus cells: an in-vitro study.

BACKGROUND: Fluoroquinolones are in wide clinical use as safe and effective antibiotics. Articular cartilage, tendons, and epiphyseal growth plates have been recognized as targets of fluoroquinolone-induced connective tissue toxicity. However, the effects of fluoroquinolones on annulus fibrosus (AF) cells are still unknown. MATERIAL/METHODS: The main objective of this study was to investigate the effects of levofloxacin, a typical fluoroquinolone antibiotic drug, on rat AF cells in vitro. Rat annulus fibrosus (RAF) cells were treated with levofloxacin at different concentrations (0, 10, 20, 30, 40, 60, 80, and 90 µg/ml) and were assessed to determine the possible cytotoxic effects of levofloxacin. Inverted phase-contrast microscopy was used to accomplish the morphological observation of apoptosis of treated cells. Western blot and real-time quantitative RT-PCR (qPCR) was used to explore the expression of active caspase-3 and MMP-3. Flow cytometry was used to measure the apoptotic incidences. RESULTS: Our study showed that levofloxacin, with concentrations at 30, 60, and 90 µg/ml, induced dose-dependent RAF cell apoptosis and higher expression of caspase-3 and MMP-3. More apoptotic cells were observed by inverted phase-contrast microscopy. Moreover, levofloxacin increased the activity of caspase-3, and it also reduced cell viability with different concentrations ranging from 10 to 80 µg/ml. CONCLUSIONS: Our study results suggest that levofloxacin has cytotoxic effects on RAF cells, characterized by enhancing apoptosis and reducing cell viability, and indicate a potential toxic effect of fluoroquinolones on RAF cells.

Comparison of toxicities of moxifloxacin, cefuroxime, and levofloxacin to corneal endothelial cells in vitro.

PURPOSE: To evaluate and compare the toxic effects of moxifloxacin, cefuroxime, and levofloxacin on human corneal endothelial cells in vitro and determine the safe intracameral concentrations for them. SETTING: Tottori University, Tottori, Japan. DESIGN: Experimental study. METHODS: Human corneal endothelial cells in culture were exposed to moxifloxacin, cefuroxime, and levofloxacin at concentrations up to 2000 µg/mL. Evaluation of membrane damage was determined by ethidium homodimer-1 uptake and cell viability, by intrinsic esterase activity. The inhibitory effects of the 3 antibiotics on the constitutive secretion of interleukin-6 (IL-6) by human corneal endothelial cells were determined by enzyme-linked immunosorbent assay. RESULTS: The acute effects (6 hour) of the 3 antibiotics on membrane damage and cell death were dose-dependent for moxifloxacin and levofloxacin (≥ 500 µg/mL). For cefuroxime, membrane damage was not observed at 6 hours and only slight damage was detected at 24 hours at concentrations higher than 500 µg/mL. The half maximum inhibitory concentrations on cell viability of moxifloxacin, levofloxacin, and cefuroxime were 487 µg/mL, 578 µg/mL, and 1600 µg/mL, respectively. The inhibitory effects of the 3 antibiotics on the constitutive secretion of IL-6 were observed at 15.6 µg/mL or higher, indicating the antibiotics can impair the secretion of the protective cytokine even at low concentrations. CONCLUSIONS: Moxifloxacin at more than 500 µg/mL caused damage to the cell membranes of corneal endothelial cells; even higher concentrations decreased cell viability. Considering the lower minimum inhibitory concentration for inhibiting 90% growth by moxifloxacin, intracameral moxifloxacin at 500 µg/mL or less is recommended for prophylactic use. FINANCIAL DISCLOSURE: Dr. Inoue is a medical advisor to Alcon Japan Ltd. No author has a financial or proprietary interest in any material or method mentioned.

Assessment of musculoskeletal toxicity 5 years after therapy with levofloxacin.

BACKGROUND: Safety concerns for fluoroquinolones exist from animal studies demonstrating cartilage injury in weight-bearing joints, dependent on dose and duration of therapy. For children treated with levofloxacin or comparator in randomized, prospective, comparative studies for acute otitis media and community-acquired pneumonia, this 5-year follow-up safety study was designed to assess the presence/absence of cartilage injury. METHODS: Children enrolled in treatment studies were also enrolled in a 1-year follow-up safety study, which; focused on musculoskeletal adverse events (MSAE). Those with persisting MSAEs, protocol-defined musculoskeletal disorders, or of concern to the Data Safety and Monitoring Committee were requested to enroll in four additional years of follow-up, the subject of this report. RESULTS: Of the 2233 subjects participating in the 12-month follow-up study, 124 of 1340 (9%) of the levofloxacin subjects, and 83 of 893 (9%) of the comparator subjects were continued for 5-year posttreatment assessment. From children identified with an MSAE during years 2 through 5 posttreatment, the number that were "possibly related" to drug therapy was equal for both arms: 1 of 1340 for levofloxacin and 1 of 893 for comparator. Of all cases of MSAE assessed by the Data Safety and Monitoring Committee at 5 years' posttreatment, no case was assessed as "likely related" to study drug. CONCLUSIONS: With no clinically detectable difference between levofloxacin- and comparator-treated children in MSAEs presenting between 1 and 5 years in these safety studies, risks of cartilage injury with levofloxacin appear to be uncommon, are clinically undetectable during 5 years, or are reversible.

In vitro and in vivo effectiveness evaluation of balofloxacin in experimental Staphylococcus aureus keratitis.

PURPOSE: To evaluate the effectiveness of balofloxacin for treatment of experimental Staphylococcus aureus keratitis. METHODS: In vitro testing compared the cellular toxicity of and bacterial susceptibility to balofloxacin and levofloxacin in human corneal epithelial cells (HCECs). For in vivo testing, experimental bacterial keratitis was induced and treated with balofloxacin eye drops (0.5%) and levofloxacin eye drops (0.5%). RESULTS: In vitro toxicity examinations showed that balofloxacin, as well as levofloxacin, had low cytotoxicity in HCECs. Balofloxacin eye drops (0.5%) also showed a similar relative cytotoxicity to levofloxacin eye drops (0.5%). In bacterial susceptibility examinations, both balofloxacin and levofloxacin significantly reduced S. aureus compared with the untreated control (P<0.001 for both balofloxacin and levofloxacin). Balofloxacin was more effective than levofloxacin in the treatment of S. aureus bacterial keratitis (P<0.05). In experimental bacterial keratitis treatment testing, balofloxacin was also more effective than levofloxacin with respect to the parameters of physiological score, histological observation, and bacterial quantitation (P<0.05). CONCLUSIONS: Balofloxacin was safe in the treatment of S. aureus bacterial keratitis, and more effective than levofloxacin. Therefore, balofloxacin was shown to have potential clinical value in ophthalmic local application.

Construction and analysis of a human hepatotoxicity database suitable for QSAR modeling using post-market safety data.

Drug-induced liver injury (DILI) is one of the most common drug-induced adverse events (AEs) leading to life-threatening conditions such as acute liver failure. It has also been recognized as the single most common cause of safety-related post-market withdrawals or warnings. Efforts to develop new predictive methods to assess the likelihood of a drug being a hepatotoxicant have been challenging due to the complexity and idiosyncrasy of clinical manifestations of DILI. The FDA adverse event reporting system (AERS) contains post-market data that depict the morbidity of AEs. Here, we developed a scalable approach to construct a hepatotoxicity database using post-market data for the purpose of quantitative structure-activity relationship (QSAR) modeling. A set of 2029 unique and modelable drug entities with 13,555 drug-AE combinations was extracted from the AERS database using 37 hepatotoxicity-related query preferred terms (PTs). In order to determine the optimal classification scheme to partition positive from negative drugs, a manually-curated DILI calibration set composed of 105 negatives and 177 positives was developed based on the published literature. The final classification scheme combines hepatotoxicity-related PT data with supporting information that optimize the predictive performance across the calibration set. Data for other toxicological endpoints related to liver injury such as liver enzyme abnormalities, cholestasis, and bile duct disorders, were also extracted and classified. Collectively, these datasets can be used to generate a battery of QSAR models that assess a drug's potential to cause DILI.