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Pharmacodynamics and pharmacokinetics of A-80556 using microdialysis in a Streptococcus pneumoniae meningitis model
C J Destache1, C B Pakiz, A M Stoysich
1Creighton University School of Pharmacy and Allied Health Professions and Medicine, Omaha, NE 68178, USA. CDESTACH@hslpharmacy.creighton.edu
Abstract:
Using microdialysis in a rabbit model of Streptococcus pneumoniae meningitis, the pharmacokinetics and pharmacodynamics of a new fluoroquinolone, A-80556, were determined. A-80556 (10 mg/kg iv) was administered to four rabbits. Saline was given to four separate control animals. A microdialysis probe perfused the CSF (2 microL/min) and effluent was collected at 0-0.25, 0.25-1, 1-2, 2-4, and 4-6 h after injection of A-80556. Seven blood samples were collected and analyzed by HPLC. At 0, 2, 4 and 6 h 300 microL of CSF was withdrawn for pharmacodynamic measurements. Plasma A-80556 concentrations demonstrated AUC0-infinity 2.40 +/- 0.272 micrograms.h/mL; T1/2 beta 1.07 +/- 0.011 h; Vd 6.35 +/- 0.50 L/kg; and Cl1 4.23 +/- 0.48 L/h.kg. Penetration into the CSF was 18.21%. Pharmacodynamics using time-kill curves showed a 3-log reduction in bacterial counts in CSF at 2 h after administration continuing for the remaining four hours of the experiment. These results demonstrate that microdialysis can be used for determination of drug penetration and efficacy in experimental S. pneumoniae meningitis.
Insights
This study shows microdialysis effectively measures A-80556 penetration and efficacy in Streptococcus pneumoniae meningitis rabbit models. The fluoroquinolone demonstrated significant bacterial reduction in cerebrospinal fluid (CSF).
Area of Science:
- Pharmacology
- Infectious Diseases
- Neuroscience
Background:
- Streptococcus pneumoniae meningitis is a serious infection requiring effective antibiotic treatment.
- Understanding drug pharmacokinetics and pharmacodynamics in the cerebrospinal fluid (CSF) is crucial for treatment efficacy.
- Novel fluoroquinolones require thorough evaluation in relevant disease models.
Purpose of the Study:
- To determine the pharmacokinetics and pharmacodynamics of the novel fluoroquinolone A-80556.
- To assess A-80556 penetration into the CSF in a rabbit model of S. pneumoniae meningitis.
- To evaluate the efficacy of A-80556 using time-kill curves in CSF.
Main Methods:
- A rabbit model of Streptococcus pneumoniae meningitis was established.
- Microdialysis was employed to measure A-80556 concentrations in CSF over time.
- High-performance liquid chromatography (HPLC) was used for drug analysis in plasma and CSF.
- Time-kill curves were utilized for pharmacodynamic assessment of bacterial reduction.
Main Results:
- A-80556 achieved significant plasma concentrations with a half-life of approximately 1.07 hours.
- CSF penetration of A-80556 was determined to be 18.21%.
- Pharmacodynamic studies showed a 3-log reduction in bacterial counts within 2 hours, sustained for 6 hours.
Conclusions:
- Microdialysis is a viable method for assessing drug penetration and efficacy in experimental meningitis.
- A-80556 demonstrates promising pharmacokinetic and pharmacodynamic properties for treating S. pneumoniae meningitis.
- These findings support further investigation of A-80556 as a potential therapeutic agent.