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Antimicrobial Agents and Chemotherapy, Sep 1996, 2126-2130, Vol 40, No. 9
L Rabbaa, S Dautrey, N Colas-Linhart, C Carbon and R Farinotti
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.
Copyright © 1996 by the American Society for Microbiology. All rights reserved.
Intestinal elimination of ofloxacin enantiomers in the rat: evidence of a carrier-mediated process
Service de Pharmacie Clinique, Centre Hospitalier Universitaire Bicha- Claude Bernard, Paris, France.
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