Moxifloxacin penetration into human gastrointestinal tissues

Martin Wirtz1, Jörg Kleeff1,*, Stefanie Swoboda2,3, Irfan Halaceli1, Heiko K. Geiss2, Torsten Hoppe-Tichy3, Markus W. Büchler1 and Helmut Friess1

1 Department of General Surgery, University of Heidelberg, Im Neuenheimer Feld 110, D-69120 Heidelberg; 2 Institute of Hygiene, University of Heidelberg, Im Neuenheimer Feld 324, D-69120 Heidelberg; 3 Pharmacy Department, University of Heidelberg, Im Neuenheimer Feld 670, D-69120 Heidelberg, Germany

Received 13 November 2003; returned 16 January 2004; revised 31 January 2004; accepted 6 February 2004


    Abstract
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
Objective: Moxifloxacin is a recently developed fourth-generation methoxyquinolone with a broad spectrum of activity against both Gram-positive and Gram-negative aerobic bacteria and anaerobes. The aim of the present study was to assess the penetration of moxifloxacin into gastrointestinal (GI) mucosal tissues to evaluate its potential role as an antimicrobial drug in bacterial infections of the GI tract.

Patients and methods: Twenty-eight patients undergoing GI-tract surgery received 400 mg of moxifloxacin twice pre-operatively [eight patients orally (po) and 20 patients intravenously (iv)], of whom 22 completed the study. Mucosal tissues (three stomach, three small bowel and 16 colon) and serum samples were collected and moxifloxacin concentrations were measured by HPLC.

Results: The highest tissue concentrations were detected in the mucosa of the stomach (10.9 ± 5.1 mg/kg), followed by colon mucosa (7.8 ± 7.1 mg/kg after iv; 6.6 ± 3.6 mg/kg after po) and small bowel mucosa (5.4 ± 0.5 mg/kg). The tissue-to-serum ratio of moxifloxacin was 2.0 ± 1.6 in the small bowel mucosa, 5.8 ± 3.4 and 6.8 ± 3.9 in the colon mucosa after po and iv administration, respectively, and 9.7 ± 5.7 in the stomach mucosa.

Conclusion: Moxifloxacin penetrates into and accumulates in the mucosa of the stomach, small bowel and colon. The clinical applicability of moxifloxacin administration for bacterial GI-tract infections should be investigated in controlled trials.

Keywords: methoxyquinolone, bacterial infection, tissue concentrations


    Introduction
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
Moxifloxacin is a recently developed methoxyquinolone antimicrobial with a broad spectrum of activity against respiratory pathogens. In contrast to earlier quinolones moxifloxacin has excellent in vitro activity against both Gram-positive and Gram-negative aerobic bacteria,1 including ß-lactamase-producing aerobic Gram-positive cocci, Haemophilus, Moraxella, intracellular and atypical microorganisms, and aerobic Gram-negative microorganisms other than Pseudomonas.2 In particular, moxifloxacin is more active against anaerobic bacteria than currently available quinolones. Moxifloxacin has a high oral bioavailability3 and its absorption is not influenced by food intake or gastric pH.

Since moxifloxacin has good antimicrobial activity against both anaerobic and aerobic bacteria, the aim of the study was to investigate the penetration and accumulation of the drug in different tissues of the alimentary tract.


    Materials and methods
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
The study population consisted of 28 patients undergoing elective gastrointestinal (GI) surgery in the Department of General Surgery, University of Heidelberg, Germany, of whom 22 patients completed the study (Table 1). Mucosal tissue samples were collected from stomach, small bowel and colon. Two additional patients undergoing elective colon resection served as controls to confirm our analytical setup and received a single shot standard perioperative antibiotic prophylaxis (4 g mezlocillin/0.5 g metronidazole).


View this table:
[in this window]
[in a new window]
 
Table 1. Demographic and medical data
 
The study group received two doses of moxifloxacin (400 mg each) prior to surgery. The first dose was scheduled to be given 22 ± 2 h before surgery and the second dose 2 h prior to the operation (defined as the time of first incision). The study patients received no other antimicrobial prophylaxis perioperatively and no other medications that potentially interact with moxifloxacin. Moxifloxacin was administered intravenously (60 min infusion; iv group) in all subjects except for a subgroup of eight patients undergoing colonic resection who received the same dose of the study drug orally (po group) with the same schedule. Prior to drug administration, peripheral venous blood samples were obtained and analysed to confirm that no moxifloxacin was taken prior to the study. After removal of the resected tissue, the mucosa was macroscopically separated, washed with deionized water and immediately snap frozen in liquid nitrogen. At the same time, a further blood sample was obtained. Serum was separated by centrifugation (2772g, 10 min). All samples were stored at –80°C until analysis.

Exclusion criteria, other than the general exclusion criteria in accordance with the manufacturer’s instructions, were (i) administration of moxifloxacin within 7 days before surgery, (ii) known allergy to fluoroquinolones, (iii) history of or present inflammatory bowel disease, and (iv) presence of sigma diverticulitis.

The protocol was approved by the Ethics Committee of the University of Heidelberg, and written informed consent was obtained from all patients.

Analytical method

Moxifloxacin concentration was determined by HPLC with fluorometric detection, as described by Stass & Dalhhoff.3 Briefly, serum samples spiked with the internal standard levofloxacin (Aventis Pharmaceuticals, Germany) were prepared by protein precipitation using a precipitation reagent consisting of acetonitrile and orthophosphoric acid 0.1 M (9:1 v/v). Tissue samples were homogenized with an Ultra Turrax disperser and then deproteinized with the precipitation reagent. After centrifugation (10°C, 7826g, 10 min), 20 µL of supernatant was injected into the analytical column (Purospher RP-18e column, 5 µm, 250 x 4 mm). The mobile phase consisted of an aqueous solution of 0.01 M tetrabutyl ammonium sulphate and 0.05 M sodium dihydrogen phosphate (a, pH 3.0) and acetonitrile. Moxifloxacin and the internal standard were eluted using a gradient elution method as described previously in detail.3 The analysis was performed at 50°C. The fluorescence detector (Perkin-Elmer, Germany) was set at excitation and emission wavelengths of 296 and 504 nm, respectively. The standard curve with five concentrations of moxifloxacin (serum/tissue) was linear over the usable concentration range of 0.05–4 mg/L. Calibration standards for tissues were prepared as described previously.4 The analytical method provided good validation data for accuracy and precision (QC samples). The inter-day coefficients of variation (0.1, 1.0, 4.0 mg/L) were <5%. The limit of quantification was determined as 0.05 mg/L. A cross-validation to external controls (Bayer AG, Germany) was carried out successfully.

Statistics

Data are expressed as mean ± standard deviation (S.D.), unless indicated otherwise. All statistical analysis was performed using SPSS for Windows, release 10 (SPSS Inc., Chicago, IL, USA). For comparison of drug concentrations for different forms of administration and at different sampling sites, the Mann–Whitney U test was used.


    Results
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
Twenty-eight patients were enrolled in this study (Table 1). Six patients from the iv group did not complete the study: two patients experienced weak symptoms of nausea, one patient suffered from transient local skin rash, one patient refused the second medication without mentioning any reason and in two patients tissue collection was missed. These patients were excluded from further analysis, leaving a study group of 22 patients. In the intravenous subgroup, the first dose of moxifloxacin was administered ~23 h (1380 ± 230 min) before the operation started and the second dose was administered preoperatively, ~5.5 h (327 ± 155 min) before tissue removal. In the po group, the first dose was given 21.5 h (1288 ± 226 min) before surgery and the second dose 4 h (250 ± 66 min) before tissue removal. These time points were not significantly different from the respective times in the iv group. One patient in the po group received the first dosage 47 h before surgery because his operation was rescheduled to the next day.

Serum concentrations were obtained after intravenous administration in 14 patients and gave mean moxifloxacin concentrations of 0.92 ± 0.98 mg/L at 17.5 h (1055 ± 194 min) after the first administration and 1.58 ± 1.08 mg/L at 5.5 h (327 ± 155 min) after the second dose. The concentrations in the po subgroup were slightly lower, being 0.69 ± 0.49 mg/L at 17 h (1040 ± 395 min) after the first dose and 1.27 ± 0.77 mg/L at 4 h (250 ± 66 min) after the second dose. However, these differences in concentration were not statistically significant.

The highest tissue concentration was seen in the stomach mucosa (10.9 ± 5.1 mg/kg), followed by the colon mucosa (7.8 ± 7.1 mg/kg after iv administration, 6.6 ± 3.6 mg/kg after po administration) and the small bowel mucosa (5.4 ± 0.5 mg/kg) (Figure 1). The tissue-to-serum ratio of moxifloxacin was 2.0 ± 1.6 in the small bowel mucosa, 5.8 ± 3.4 and 6.8 ± 3.9 in the colon mucosa after po and iv administration, respectively, and 9.7 ± 5.7 in the stomach mucosa (Figure 1). In the control patients neither blood nor tissue analysis revealed detectable levels of moxifloxacin, confirming our analytical settings.



View larger version (18K):
[in this window]
[in a new window]
 
Figure 1. Serum (mg/L) and tissue (mg/kg) moxifloxacin concentrations for the indicated tissues. The time between last drug administration and concentration determination were as follows: small bowel 4.5 h (273.3 ± 151.2 min), colon po 4 h (250.0 ± 66.0 min), colon iv 6 h (362.8 ± 170.6 min) and stomach 4.5 h (275.0 ± 125.8 min). The tissue-to-serum ratio is given on the connection line between the serum and tissue concentrations. All values are presented as mean ± standard error of the mean (S.E.M.).

 

    Discussion
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
To assess whether a new antimicrobial drug is likely to be of value in the therapy and/or prophylaxis of bacterial GI infections, it is important to determine the tissue concentrations of the agent, since drug concentrations in plasma do not reliably predict clinical efficacy.5 The objective of the present study, therefore, was to determine the tissue concentrations of moxifloxacin in tissues of the alimentary tract and to compare these concentrations with the serum concentrations in order to evaluate whether this new quinolone accumulates in GI-tract tissues.

The highest tissue concentrations of moxifloxacin were found in the mucosa of the stomach (10.9 ± 5.1 mg/kg); these were up to 9.7 times higher than the serum concentrations, indicating accumulation of the drug in these tissues. The lowest mucosal tissue concentrations were observed in the small bowel (5.4 ± 0.5 mg/kg), which nonetheless exceeded the MIC90 for most anaerobic bacteria (2 mg/L).6

Serum concentrations of moxifloxacin determined ~17 h after the first drug administration were within the range of those found by Stass & Kubitza,7 whereas moxifloxacin serum concentrations measured ~5 h after the second administration were somewhat lower than expected, most likely due to serum dilution effects, i.e. iv fluid application and blood loss during surgery.

Our observation of high tissue concentrations in the alimentary tract might open a new perspective for the potential use of moxifloxacin in bacterial infections of the alimentary tract. Since a recent clinical study showed that a moxifloxacin-based triple therapy resulted in 90% eradication of Helicobacter pylori8,9 and high moxifloxacin tissue concentrations were found in the stomach, this drug could be considered as a candidate in the eradication schema for H. pylori.

Although the comparison of moxifloxacin tissue concentrations does not provide evidence that a high and effective concentration is also present at the site of infection or site of contamination, we nonetheless hypothesize that effective drug levels might be present in the extracellular luminal environment in the lower GI tract. This is also supported by data from Edlund et al.,1 who demonstrated high moxifloxacin levels in the faeces, well above the MIC for many groups of microorganisms in the normal microflora.

The potential role of moxifloxacin for the treatment of bacterial infections of the alimentary tract such as sigma diverticulitis and bacterial gastroenteritis is promising and should therefore be further investigated in controlled clinical trials.


    Acknowledgements
 
This study was supported in part by Bayer AG, Germany.


    Footnotes
 
* Corresponding author. Tel: +49-6221-564860; Fax: +49-6221-566903; E-mail: joerg_kleeff{at}med.uni-heidelberg.de Back


    References
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 References
 
1 . Edlund, C., Beyer, G., Hiemer-Bau, M. et al. (2000). Comparative effects of moxifloxacin and clarithromycin on the normal intestinal microflora. Scandinavian Journal of Infectious Diseases 32, 81–5.[CrossRef][ISI][Medline]

2 . Blondeau, J. M. (1999). A review of the comparative in-vitro activities of 12 antimicrobial agents, with a focus on five new ‘respiratory quinolones’. Journal of Antimicrobial Chemotherapy 43, Suppl. B, 1–11.[Free Full Text]

3 . Stass, H. & Dalhoff, A. (1997). Determination of BAY 12-8039, a new 8-methoxyquinolone, in human body fluids by high-performance liquid chromatography with fluorescence detection using on-column focusing. Journal of Chromatography B, Biomedical Sciences and Applications 702, 163–74.[CrossRef]

4 . Bottcher, S., von Baum, H., Hoppe-Tichy, T. et al. (2001). An HPLC assay and a microbiological assay to determine levofloxacin in soft tissue, bone, bile and serum. Journal of Pharmaceutical and Biomedical Analysis 25, 197–203.[CrossRef][ISI][Medline]

5 . Eichler, H. G. & Muller, M. (1998). Drug distribution. The forgotten relative in clinical pharmacokinetics. Clinical Pharmacokinetics 34, 95–9.[ISI][Medline]

6 . Aldridge, K. E. & Ashcraft, D. S. (1997). Comparison of the in vitro activities of Bay 12-8039, a new quinolone, and other antimicrobials against clinically important anaerobes. Antimicrobial Agents and Chemotherapy 41, 709–11.[Abstract]

7 . Stass, H. & Kubitza, D. (1999). Pharmacokinetics and elimination of moxifloxacin after oral and intravenous administration in man. Journal of Antimicrobial Chemotherapy 43, Suppl. B, 83–90.[Abstract/Free Full Text]

8 . Sanchez, J. E., Saenz, N. G., Rincon, M. R. et al. (2000). Susceptibility of Helicobacter pylori to mupirocin, oxazolidinones, quinupristin/dalfopristin and new quinolones. Journal of Antimicrobial Chemotherapy 46, 283–5.[Abstract/Free Full Text]

9 . Di Caro, S., Ojetti, V., Zocco, M. A. et al. (2002). Mono, dual and triple moxifloxacin-based therapies for Helicobacter pylori eradication. Alimentary Pharmacology and Therapeutics 16, 527–32.[CrossRef][ISI][Medline]