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Antimicrobial Agents and Chemotherapy, October 1998, p. 2650-2655, Vol. 42, No. 10
The University of Texas Southwestern Medical
Center, Dallas, Texas
Received 9 February 1998/Returned for modification 31 May
1998/Accepted 20 July 1998
The purpose of this study was to evaluate the cerebrospinal fluid
(CSF) pharmacodynamics of a new fluoroquinolone, gatifloxacin (AM-1155), in experimental pneumococcal meningitis. The penetration of
gatifloxacin into CSF, calculated as the percentage of the area under
the concentration-time curve (AUC) in CSF over the AUC in blood, was 46 to 56%. Gatifloxacin showed linear pharmacokinetics in CSF, and 1 h after intravenous dosages of 7.5, 15, or 30 mg/kg of body weight,
peak CSF concentrations were 0.46 ± 0.08 (mean ± standard
deviation), 0.94 ± 0.16, and 1.84 ± 0.5 µg/ml,
respectively. The elimination half-life of gatifloxacin in CSF was 3.8 to 5.6 h (compared with 2.7 to 3.2 h in blood). There was a
significant interrelationship among the highest measured values of
gatifloxacin in blood and CSF/minimal bactericidal concentration
(Cpeak/MBC), the time antibiotic concentrations
exceeded the MBC (T > MBC), and AUC/MBC
(r = 0.94); in single-dose experiments, each
correlated significantly with the bacterial killing rate. Divided-dose
regimens, resulting in greater T > MBC values but
lower Cpeak/MBC ratios, were more effective in
terms of bacterial clearance compared with corresponding single-dose
regimens. Gatifloxacin therapy was as effective as currently
recommended regimens (e.g., a combination of ceftriaxone and
vancomycin) against this highly cephalosporin-resistant pneumococcal
strain. The bactericidal activity of gatifloxacin in CSF was closely
related to the AUC/MBC ratio, but maximal activity was achieved only
when drug concentrations exceeded the MBC for the entire dosing
interval.
0066-4804/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Pharmacodynamics of Gatifloxacin in Cerebrospinal
Fluid in Experimental Cephalosporin-Resistant Pneumococcal
Meningitis
*
Corresponding author. Mailing address: Department of
Pediatrics, Southwestern Medical Center, 5323 Harry Hines Blvd.,
Dallas, TX 75235-9063. Phone: (214) 648-3082. Fax: (214) 648-2961. E-mail: GMCCRA{at}mednet.swmed.edu.
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