1 Department of Medical Microbiology, City Hospital NHS Trust, Birmingham; 2 Department of Respiratory Medicine, Heartlands NHS Trust, Birmingham; 3 Hammersmith Medicines Research Ltd, Central Middlesex Hospital, London, UK; 4 Bristol-Myers Squibb, USA
Received 27 August 2002; returned 7 November 2002; revised 15 November 2002; accepted 3 December 2002
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Abstract |
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Keywords: garenoxacin, concentrations, respiratory tree
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Introduction |
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Materials and methods |
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Twenty-four healthy subjects, 14 men (mean age 22.4 years, mean weight 81.8 kg) and 10 women (mean age 29.5 years, mean weight 57.5 kg), were enrolled into the study at Hammersmith Medicines Research at the Central Middlesex Hospital in London, UK. Subjects were dosed with 600 mg oral garenoxacin, and the plasma and lung tissue samples were collected at one of four time intervals: interval 1, 2.53.5 h; interval 2, 4.55.5 h; interval 3, 10.511.5 h; and interval 4, 23.524.5 h. The Hospital Ethics Committee approved the study and all subjects gave written informed consent. All subjects were screened within 14 days prior to bronchoscopy; screening included a detailed medical history, physical examination, blood samples for haematological and biochemical analysis and, in the case of females, a pregnancy test.
Sample collection
Bronchoscopy samples were collected as described previously.6 Briefly, at bronchoscopy bronchial mucosa (BM) and broncho-alveolar lavage (BAL) were taken using standard procedures.7 In the case of BAL, 200 mL of pre-warmed 0.9% saline was divided into four 50 mL aliquots. The aspirate from the first aliquot was discarded to avoid contamination of the sample with proximal airway fluids and cells; the remaining aspirates were pooled for analysis.
Microbiological assay
Concentrations of garenoxacin were measured using methods based on those described previously.8 Assay plates (Mast Diagnostics, Bootle, UK) containing Iso-Sensitest agar (Oxoid, Basingstoke, UK) were flooded with an Escherichia coli (4004; Bayer, Wuppertal, AG, Germany) suspension adjusted to an optical density of 0.004 at 630 nm. Antibiotic calibrators were prepared in pooled human serum and pH 7 buffer (range 0.061 mg/L) and 9% saline (range 0.122 mg/L). Internal control samples (0.8 and 0.08 mg/L prepared in human serum and pH 7 buffer; 1.5 and 0.2 mg/L prepared in 9% sodium chloride) and quality assurance samples (range 0.070.9 mg/L for human serum and pH 7 buffer; range 0.151.8 mg/L for 9% sodium chloride) were included on every assay plate. Five millimetre holes were punched in the agar, and tests, calibrators, control and quality assurance samples were applied in triplicate to the plate. After overnight incubation at 30°C, zones were measured using an image analyser pre-programmed with Bennets calculation9 (Imaging Associates, Thame, UK).
Calculation of garenoxacin in epithelial lining fluid (ELF), alveolar macrophages (AM) and BM
Concentrations of antibiotic were calculated using the following formulae:
BM.
AC x (VB + WS)/WS = Concentration (mg/kg tissue)
where AC = assayed concentration (mg/L), VB = volume of buffer added to homogenize the sample (µL) and WS = weight of tissue (mg).
ELF. The concentration of urea in BAL was determined using a modified Sigma Diagnostic Kit (UV-66, Sigma Chemicals, Poole, UK).
ACL x BL/UL = ELF concentration (mg/L)
where ACL = assayed concentration (mg/L), UL = urea concentration in lavage (mmol/L) and BL = blood urea concentration (mmol/L).
AM. Antibiotic concentration in AMs was determined using a mean cell volume of an alveolar macrophage of 2.48 µL/ 106 cells.
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Results |
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Discussion |
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Like other quinolones, we have shown a high penetration into AMs that would suggest that this drug should exhibit efficacy against Mycoplasma, Legionella and Chlamydia.12
These data suggest that garenoxacin might be effective for the treatment of respiratory infections, including those caused by pneumococci with reduced susceptibility to penicillin.
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Footnotes |
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References |
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2
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3
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Wise, R., Gee, T., Marshall, G. & Andrews, J. M. (2002). Single- dose pharmacokinetics and penetration of BMS 284756 into an inflammatory exudate. Antimicrobial Agents and Chemotherapy 46, 2424.
4 . Wise, R. & Honeybourne, D. (1996). A review of the penetration of sparfloxacin into the lower respiratory tract and sinuses. Journal of Antimicrobial Chemotherapy 37, Suppl. A, 5763.[ISI][Medline]
5 . Honeybourne, D., Andrews, J. M., Ashby, J. P., Lodwick, R. & Wise, R. (1988). Evaluation of the penetration of ciprofloxacin and amoxycillin into the bronchial mucosa. Thorax 43, 7159.[Abstract]
6 . Andrews, J. M., Honeybourne, D., Brenwald, N. P., Banergee, D., Iredale, M., Cunningham, B. et al. (1997). Concentrations of trovafloxacin in bronchial mucosa, epithelial lining fluid, alveolar macrophages and serum after administration of single or multiple oral doses to patients undergoing fibre-optic bronchoscopy. Journal of Antimicrobial Chemotherapy 39, 797802.[Abstract]
7 . The BAL Cooperative Group Steering Committee. (1990). Bronchoalveolar lavage constituents in healthy individuals, idiopathic pulmonary fibrosis, and selected comparison groups. American Review of Respiratory Disease 141, 166202.
8 . Andrews, J. M. (1999). The assay of antimicrobials in tissues and fluids. In Clinical Antimicrobial Assays (Reeves, D. S., Wise, R., Andrews, J. M. & White, L. O., Eds), pp. 6575. Oxford University Press, New York, NY, USA.
9 . Bennet, J. V., Brodie, J. L., Benner, E. J. & Kirby, W. M. (1966). Simplified, accurate method for antibiotic assay of clinical specimens. Applied Microbiology 14, 1707.[ISI][Medline]
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Andrews, J. M. & Wise, R. (2001). In vitro susceptibility testing of garenoxacin by the BSAC standardized disc testing method. Journal of Antimicrobial Chemotherapy 48, 32234.
11 . Zhanel, G. G., Palatnick, L., Weshnoweski, B., Smith, H., Nichol, K. & Hoban, D. J. (2001). BMS-284756 demonstrates potent activity against Canadian lower respiratory tract infection (RTI) pathogens isolated in 19992001. In Program and Abstracts of the Forty-first Interscience Conference on Antimicrobial Agents and Chemotherapy, Chicago, IL, USA, 2001. Abstract E-711, p. 176. American Society for Microbiology, Washington, DC, USA.
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Malay, S., Roblin, P. M., Reznik, T., Kutlin, A. & Hammerschlag, M. R. (2002). In vitro activities of BMS-284756 against Chlamydia trachomatis and recent clinical isolates of Chlamydia pneumoniae. Antimicrobial Agents and Chemotherapy 46, 5178.