Search results for "Quinolones"
showing 10 items of 103 documents
Mathematical modeling of oral absorption and bioavailability of a fluoroquinolone after its precipitation in the gastrointestinal tract
2013
The objective was to characterize the in vivo absorption and bioavailability (BA) of a low solubility, high permeability fluoroquinolone (CNV97101) that precipitates in the gastrointestinal (GI) tract by mathematical modeling approach. In situ rat intestinal perfusion studies were performed to characterize the absorption mechanism. The oral fraction absorbed in vivo was lower than the predicted based on the in situ intestinal permeability. Two additional routes of administration, intraduodenal (ID) and intraperitoneal (IP) were investigated to explore if precipitation in stomach and subsequent partial re-dissolution were the causes of the lower in vivo BA. Ex vivo precipitation studies with…
In situ kinetic modelling of intestinal efflux in rats: functional characterization of segmental differences and correlation with in vitro results.
2007
The objective was to devise and apply a novel modelling approach to combine segmental in situ rat perfusion data and in vitro cell culture data, in order to elucidate the contribution of efflux in drug absorption kinetics. The fluoroquinolone CNV97100 was used as a model P-gp substrate. In situ intestinal perfusion was performed in rat duodenum, jejunum, ileum and colon to measure the influence of P-gp expression on efflux. Inhibition studies of CNV97100 were performed in the presence of verapamil, quinidine, cyclosporin A and p-aminohippuric acid. Absorption/efflux parameters were modelled simultaneously, using data from both in situ studies as well as in vitro studies. The maximal efflux …
Development of a long-lasting ventricular catheter impregnated with a combination of antibiotics.
2003
A ventricular silicone catheter impregnated with a combination of rifampin and a quinolone was developed in order to prevent ventricular shunt related infections. As model substance for the quinolones we used sparfloxacin, because of its specific physicochemical properties resulting in a quantitative detection also in the presence of a second antibiotic. In our study we focused especially on an optimization of the antibiotic release out of the impregnated catheters in order to develop long lasting devices with a broad antimicrobial spectrum. A release-optimized catheter was tested with an in vitro colonization test and additionally with a method developed to examine the spread of bacteria o…
Evaluation of HIV-1 integrase resistance emergence and evolution in patients treated with integrase inhibitors
2020
Abstract Objectives This study evaluated the emergence of mutations associated with integrase strand transfer inhibitors (INSTI) resistance (INSTI-RMs) and the integrase evolution in human immunodeficiency virus type 1 (HIV-1) infected patients treated with this drug class. Methods The emergence of INSTI-RMs and integrase evolution (estimated as genetic distance between integrase sequences under INSTI treatment and before INSTI treatment) were evaluated in 107 INSTI-naive patients (19 drug-naive and 88 drug-experienced) with two plasma genotypic resistance tests: one before INSTI treatment and one under INSTI treatment. A logistic regression analysis was performed to evaluate factors associ…
Kinetic modelling of the intestinal transport of sarafloxacin. Studiesin situin rat andin vitroin Caco-2 cells
2005
The absorption kinetics of sarafloxacin, as a model of fluoroquinolone structure, were studied in the rat small intestine and in Caco-2 cells. The objective of the study was to investigate the mechanistic basis of the drug's intestinal transport in comparison with other members of the fluoroquinolone family and to apply a mathematical modelling approach to the transport process. In the rat small intestine, sarafloxacin showed dual mechanisms of intestinal absorption with a passive diffusional component and an absorptive carrier-mediated component. The characteristics of the animal study design made it suitable for population analysis, thus allowing the accurate estimation of transport param…
Validation of a biophysical drug absorption model by the PATQSAR system
1999
Absorption rate constants (in situ rat gut technique) and in vitro antibacterial activities of twenty fluoroquinolones have been evaluated. A biophysical model that relates the absorption of the compounds with their lipophilicity was fitted. The model considers the absorption process from the intestinal lumen as the sum of two resistances in series: aqueous diffusional barrier and lipoidal membrane. Even if partitioning into the membrane and membrane diffusion are both enhanced for lipophilic compounds, the absorption rate constant is limited by the aqueous diffusion. To estimate the influence of structural modifications on each property and to establish the role of lipophilicity in control…
A novel approach to determining physicochemical and absorption properties of 6-fluoroquinolone derivatives: experimental assessment
2002
The ToSS MoDe approach is used to estimate the n-octanol/buffer partition coefficient, the apparent intestinal absorption rate constant and intestinal permeability from a 6-fluoroquinolone data set. Improved in silico methods for predicting a drug's ability to be transported across biological membranes and other biopharmaceutical properties is highly desirable to optimize new drug development. The physicochemical property (Log P) of 26 6-fluoroquinolone derivatives and the absorption properties (Log K(a) and Log P(eff)) of 21 derivatives were well described by the present approach. The models obtained confirm the important role of lipophilicity in the absorption process and its relation wit…
Mathematical modelling of in situ and in vitro efflux of ciprofloxacin and grepafloxacin
2005
Abstract The efflux process due to p-glycoprotein-like mechanisms of ciprofloxacin (CIP) and grepafloxacin (GRX) has been studied “in situ” in rats and “in vitro” in Caco-2 cells. The results were modelled by a curve fitting procedure which allowed the characterization of the passive (Pd) and carrier mediated parameters (Vm and Km) from the raw data without initial velocities estimation. CIP absorption in rat was characterized as a passive diffusion at the assayed concentrations. Although the involvement of an efflux transporter cannot be ruled out, its relevance in the transport of the fluoroquinolone is negligible. In GRX absorption, an efflux process is implicated and it is detected in b…
Intrinsic Absolute Bioavailability Prediction in Rats Based on In Situ Absorption Rate Constants and/or In Vitro Partition Coefficients: 6‐Fluoroquin…
2000
A preliminary study attempting to predict the intrinsic absolute bioavailability of a group of antibacterial 6-fluoroquinolones-including true and imperfect homologues as well as heterologues-was carried out. The intrinsic absolute bioavailability of the test compounds, F, was assessed on permanently cannulated conscious rats by comparing the trapezoidal normalized areas under the plasma concentration-time curves obtained by intravenous and oral routes (n = 8-12). The high-performance liquid chromatography analytical methods used for plasma samples are described. Prediction of the absolute bioavailability of the compounds was based on their intrinsic rat gut in situ absorption rate constant…
Odorant metabolism catalyzed by olfactory mucosal enzymes influences peripheral olfactory responses in rats.
2013
International audience; A large set of xenobiotic-metabolizing enzymes (XMEs), such as the cytochrome P450 monooxygenases (CYPs), esterases and transferases, are highly expressed in mammalian olfactory mucosa (OM). These enzymes are known to catalyze the biotransformation of exogenous compounds to facilitate elimination. However, the functions of these enzymes in the olfactory epithelium are not clearly understood. In addition to protecting against inhaled toxic compounds, these enzymes could also metabolize odorant molecules, and thus modify their stimulating properties or inactivate them. In the present study, we investigated the in vitro biotransformation of odorant molecules in the rat …