Lomefloxacin clinical pharmacokinetics

Physicochemical properties as a function of lomefloxacin biological activity

OBJECTIVE

Aim: The goal is to discover QSAR of Lomefloxacin as antibacterial activity.

PATIENTS AND METHODS

Materials and Methods: A number of lomefloxacins analogs activities were studied by program Windows Chem SW. The analogues were obtained and energy minimization was carried out through Molecular Modeling Program, the calculations were performed using General Atomic and Molecular Electronic Structure System (GAMESS) software.

RESULTS

Results: There were six descriptions (N-quinoline more (-) ev charge, Kinetic Energy, Potential Energy, Log p, Log S, F6 charge) results have highly compatible of physicochemical properties with lomefloxacin analogs activities. It can be used to estimate the activities depending on QSAR equation of lomefloxacin analogs.

CONCLUSION

Conclusions: The parameters used for calculation were depending on the quantum chemical was employed in deriving from computational study of properties and can used to predict the activities of certain analogs of Lomefloxacins as antibacterial compounds.

Pharmacokinetic parameter prediction from drug structure using artificial neural networks

Simple methods for determining the human pharmacokinetics of known and unknown drug-like compounds is a much sought-after goal in the pharmaceutical industry. The current study made use of artificial neural networks (ANNs) for the prediction of clearances, fraction bound to plasma proteins, and volume of distribution of a series of structurally diverse compounds. A number of theoretical descriptors were generated from the drug structures and both automated and manual pruning were used to derive optimal subsets of descriptors for quantitative structure-pharmacokinetic relationship models. Models were trained on one set of compounds and validated with another. Absolute predicted ability was evaluated using a further independent test set of compounds. Correlations for test compounds ranged from 0.855 to 0.992. Predicted values agreed closely with experimental values for total clearance, renal clearance, and volume of distribution, while predictions for protein binding were encouraging. The combination of descriptor generation, ANNs, and the speed and success of this technique compared with conventional methods shows strong potential for use in pharmaceutical product development.

Effects of lomefloxacin and norfloxacin on pancreatic beta-cell ATP-sensitive K(+) channels

In patients administered lomefloxacin alterations in blood glucose concentrations have been observed in some cases and lomefloxacin has previously been shown to augment insulin release from rat pancreatic islets at micromolar concentrations. The aim of the present study was to compare the effects of two structurally related fluoroquinolones, lomefloxacin and norfloxacin, on ATP-sensitive K(+) (K(ATP)) currents from the clonal insulinoma cell line RINm5F using the whole-cell configuration of the patch-clamp technique. The application of lomefloxacin concentration-dependently blocked K(ATP) currents from RINm5F cells with a half-maximally inhibitory concentration of 81 microM, whereas the application of norfloxacin (at concentrations up to 300 microM) had only minor effects on K(ATP) currents. Block of pancreatic beta-cell K(ATP) currents could be mediated by interaction of lomefloxacin either with the regulatory subunit (SUR1) or with the pore-forming subunit (Kir6.2). We favour the latter hypothesis, since some fluoroquinolones have recently been shown to block the pore-forming subunit of the cardiac rapid delayed rectifier K(+) current I(Kr) (which is encoded by HERG (human ether-a-go-go-related gene)). Thus, as demonstrated for cardiac HERG channels in previous studies and for pancreatic beta-cell K(ATP) channels in the present study, fluoroquinolones differ markedly in their potencies to inhibit K(+) channel activity.

Kinetic characterization of secretory transport of a new ciprofloxacin derivative (CNV97100) across Caco-2 cell monolayers

The kinetics of transport of a new fluoroquinolone antibiotic (CNV97100) and its analogs were characterized using the Caco-2 cell culture model. Unidirectional permeabilities of these analogs were greater (p < 0.05) than that of ciprofloxacin. The absorptive permeabilities (P(AB)) of 4'-N-substituted analogs (CNV97101-104) were 400-600% greater, whereas the secretory permeability (P(BA)) was 25-80% greater than unsubstituted analogs because CNV97101-104 were poor substrates for efflux transporters (efflux ratio approximately 1). The transport of compounds without 4'-N-substitution (i.e., ciprofloxacin and CNV97100) favored secretion (efflux ratio approximately 4). Further characterization of CNV97100 transport revealed that it was concentration dependent (apparent K(m) = 0.484 mM, and apparent V(max) = 17.5 nmol x cm(-2) x h(-1)), and temperature dependent (E(a) = 20.57 for P(AB) and 31.45 kcal/mol for P(BA), respectively). p-Glycoprotein (p-gp)inhibitors, such as verapamil (100 microM) and cyclosporin A (CsA, 20 microM) significantly (p < 0.05) inhibited P(BA) but significantly (p < 0.05) enhanced P(AB). Multidrug resistance related protein (MRP) inhibitor leukotriene C(4) only decreased (p < 0.05) P(BA) of ciprofloxacin but not that of CNV97100. In the presence of increasing concentrations of verapamil, the P(BA) of CNV97100 decreased significantly (p < 0.05), with an IC(90) value of 96.5 microM. Taken together, these results suggested that 4'-N-alkylation of fluoroquinolones improves their absorptive permeability. Secretion of CNV97100 is dominated by p-gp, whereas the secretion of ciprofloxacin is via a combination of efflux transporters.

A thermodynamic study of complexation of ciprofloxacin and lomefloxacin with aluminium ion

Gibbs energy, enthalpy and entropy for the reactions of ciprofloxacin and lomefloxacin with aluminium ion were determined. No significant differences were observed for Gibbs energy values for these fluorquinolones while significant differences were found for enthalpy and entropy. The highly positive values observed for the entropy give evidence for a strong cation-ligand interaction and point out the role of hydration in the complex formation. As the value of the entropy for the reaction with ciprofloxacin is higher than that observed for lomefloxacin one concludes that the former ligand interacts more strongly with the metal ion than the latter.

Intestinal elimination of ofloxacin enantiomers in the rat: evidence of a carrier-mediated process

The aim of this work was to examine the mechanism involved in intestinal elimination of the two optical isomers of ofloxacin in the rat. An intestinal segment was isolated in situ and perfused with saline, while drug solution was administered via the carotid artery. Blood samples and intestinal effluents were collected and analyzed by a high-performance liquid chromatography method. We observed saturable and stereoselective intestinal elimination of the ofloxacin enantiomers. The elimination process favored the R-(+) form of the molecule. After a parenteral dose of 20 mg of racemic ofloxacin per kg of body weight, intestinal clearances were 0.23 +/- 0.03 versus 0.30 +/- 0.03 ml/min for S-(-)- and R-(+)-ofloxacin, respectively. Ciprofloxacin and pefloxacin interfered with ofloxacin elimination and significantly reduced the intestinal clearance of S-(-)- and R-(+)-ofloxacin. With concomitant ciprofloxacin, intestinal clearances became 0.13 +/- 0.02 versus 0.17 +/- 0.03 ml/min and 0.14 +/- 0.01 versus 0.19 +/- 0.05 ml/min with pefloxacin for S-(-)- and R-(+)-ofloxacin, respectively. Those findings argue for the presence of a common transport system in the rat intestine with variable affinities for fluoroquinolones. In addition, verapamil and quinidine, two P-glycoprotein blockers, significantly reduced the intestinal elimination of both ofloxacin isomers (with concomitant verapamil, intestinal clearances were 0.12 +/- 0.02 versus 0.18 +/- 0.03 ml/min for S-(-)- and R-(+)-ofloxacin, respectively, while with concomitant quinidine, values were 0.18 +/- 0.01 versus 0.23 +/- 0.01 ml/min without modifying their areas under the concentration-time curve in serum. Similar results were found with another fluoroquinolone, ciprofloxacin, in previous work. P-glycoprotein appears to be involved in the intestinal elimination of fluoroquinolones in rats. The characterization of fluoroquinolone intestinal elimination has significant clinical relevance for the better evaluation of the influence of this secretory pathway on antibiotic efficacy and selection of resistant bacteria within the intestinal flora.

Effect of probenecid and ranitidine on urinary excretion of lomefloxacin in rats

To examine the renal tubular transport pathways of lomefloxacin, a new quinolone antibiotic, the agent was injected intravenously with or without pretreatment with probenecid, an organic anion, or ranitidine, an organic cation, in rats. Urinary excretion of lomefloxacin significantly decreased in the probenecid-treated animals. However, no significant decrease was observed in this parameter by pretreatment with ranitidine. These results suggest that lomefloxacin is mainly secreted in urine by the organic anion transport system, while the pathway mediated by the organic cation transport system is negligible.