ru-66647 and Inflammation

Idiosyncratic drug-induced hepatotoxicity accounts for about 13% of all cases of acute liver failure, therefore cited as the most frequent reason for post-marketing drug withdrawal. Despite this, the underlying mechanisms remain poorly understood due to lack in adequate screening assays and predictive in vitro models. Hepatic transporters play a crucial role in the absorption, distribution, and elimination of both endogenous substrates and xenobiotics. Defects in transporter function can lead to altered drug disposition, including toxicity and loss of efficacy. Inflammation is one condition for demonstrated variable drug response, attributed in part, to changes in function of drug transporters. The present study investigates the implication of two important hepatic transporters (MDR1 and MRP2) in idiosyncratic drug-induced hepatotoxicity in the presence and absence of an inflammatory context. The synergistic effect of idiosyncratic drugs (Trovafloxacin, nimesulide, telithromycin, and nefazodone) and inflammatory stimuli (TNF-α + LPS) on the efflux activity of hepatic transporters was studied using microvolume cytometry. Our results demonstrated on the one hand that both MDR1 and MRP2 are variably implicated in idiosyncratic drug-induced liver injury and on the other hand that the occurrence of an inflammatory reaction during idiosyncratic drug therapy can noticeably modulate this implication. In the absence of an inflammatory stress, none of the four tested drugs modulated the efflux activity of MRP2; nevertheless telithromycin and nefazodone inhibited the efflux activity of MDR1. Upon occurrence of an inflammatory stress, the inhibitory potential of trovafloxacin, nimesulide, and nefazodone on the efflux activity of MRP2 was noticeably revealed, while the telithromycin and nefazodone-induced inhibition of MDR1 was clearly attenuated. Knowledge of underlying mechanisms may significantly contribute to elimination of potential hepatotoxic drugs long before marketing and to prevention of drug-induced hepatotoxicity.

Topics: ATP Binding Cassette Transporter, Subfamily B; ATP Binding Cassette Transporter, Subfamily B, Member 1; ATP-Binding Cassette Sub-Family B Member 4; Biological Transport; Chemical and Drug Induced Liver Injury; Flow Cytometry; Fluoroquinolones; Gene Expression Regulation; Hep G2 Cells; Hepatocytes; Humans; Inflammation; Ketolides; Lipopolysaccharides; Liver; Naphthyridines; Piperazines; Sulfonamides; Triazoles; Tumor Necrosis Factor-alpha; Xenobiotics

The efficacy of telithromycin, a new ketolide antibiotic, was investigated in the treatment of acute Chlamydia pneumoniae infection in a mouse model.. C57BL/6J mice were inoculated intranasally, and the effects of three different doses of telithromycin (25, 50 and 100 mg/kg) were assessed after 5 and 10 days of treatment. Lungs for culture, PCR, histopathology, and blood for serum samples were collected immediately after each treatment period and at 3 weeks post-inoculation. C. pneumoniae-specific antibodies were analysed, and the effect of treatment was assessed by culture, detection of C. pneumoniae DNA and determination of histopathological inflammatory changes in mouse lungs.. Culture negativity in the lungs was achieved with the higher doses, 50 and 100 mg/kg, after 10 days of treatment. C. pneumoniae DNA was not totally eradicated with the treatments, but the groups treated with 50 and 100 mg/kg doses for 10 days had the lowest DNA positivity rates (10%) 3 weeks after the inoculation. In lung histopathology, the efficacy of telithromycin on inflammatory changes was also dose-dependent: higher doses were more effective in reducing the inflammatory reaction. Overall, the 25 mg/kg dose had a weaker effect compared with the others.. Telithromycin had both time- and dose-dependent effects on the eradication of chlamydia and on reducing infection-induced inflammatory changes in mouse lungs.

Topics: Acute Disease; Animals; Anti-Bacterial Agents; Antibodies, Bacterial; Chlamydia Infections; Chlamydophila pneumoniae; DNA, Bacterial; Dose-Response Relationship, Drug; Female; Immunoglobulin G; Inflammation; Ketolides; Lung; Macrolides; Mice; Mice, Inbred C57BL; Pneumonia, Bacterial; Reverse Transcriptase Polymerase Chain Reaction

The penetration of telithromycin (HMR 3647), a novel ketolide antimicrobial, has been assessed in an open, single-dose study in eight healthy male subjects. Following a single, oral, 600 mg dose the mean ratio of the concentration of telithromycin in blister fluid over plasma was 1.38. Significant blister fluid concentrations were maintained up to 24 h post-dose. These results indicate that telithromycin penetrates well into inflammatory extracellular fluid, achieving high and sustained concentrations in this medium.

Topics: Administration, Oral; Adult; Anti-Bacterial Agents; Area Under Curve; Blister; Extracellular Space; Humans; Inflammation; Ketolides; Macrolides; Male; Middle Aged