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Clinical pharmacokinetics of oral levofloxacin and sitafloxacin in epididymal tissue
J Infect Chemother xxx (2016) 1e4
Contents lists available at ScienceDirect
Journal of Infection and Chemotherapy journal homepage: http://www.elsevier.com/locate/jic
Original Article
Clinical pharmacokinetics of oral levofloxacin and sitafloxacin in epididymal tissue Takuya Sadahira a, b, Koichiro Wada a, b, *, Kazuro Ikawa c, Norifumi Morikawa c, Hiroaki Kurahashi b, d, Takashi Yoshioka a, b, Yuichi Ariyoshi a, b, Yasuyuki Kobayashi a, b, Motoo Araki a, b, Ayano Ishii a, b, Masami Watanabe a, b, Shinya Uehara b, e, Toyohiko Watanabe a, b, Yasutomo Nasu a, b a
Department of Urology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1, Shikata-cho, Kita-ku, Okayama, 700-8558, Japan b Okayama Urological Research Group (OURG), 2-5-1, Shikata-cho, Kita-ku, Okayama, 700-8558, Japan c Department of Clinical Pharmacotherapy, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Hiroshima, 734-8551, Japan d Department of Urology, Tsukazaki Hospital, 68-1, Waku, Aboshi-ku, Himeji, 671-1227, Japan e Department of Urology, Kawasaki Medical School, 577, Matsushima, Kurashiki, 701-0114, Japan
a r t i c l e i n f o
a b s t r a c t
Article history: Received 18 August 2016 Received in revised form 31 October 2016 Accepted 19 December 2016 Available online xxx
Objectives: This study aimed to investigate the penetration of fluoroquinolones into human epididymal tissue. Methods: The penetration of levofloxacin (LVFX) 500 mg or sitafloxacin (STFX) 100 mg into epididymal tissue was examined. Patients with prostate cancer who were referred for orchiectomy were included. LVFX 500 mg (n ¼ 9) or STFX 100 mg (n ¼ 9) was administered orally 1 h before orchiectomy, and 0.5 g of epididymal tissue and blood samples were collected simultaneously during surgery. Drug concentrations were measured by high-performance liquid chromatography, and patient characteristics and adverse events were analyzed. Results: The mean ratio of the epididymal concentration to the serum concentration was 1.48 ± 0.45 for LVFX and 1.54 ± 0.81 for STFX. For LVFX, the simulated curves estimated the following: maximum concentrations (Cmax) of 8.84 mg/ml in serum and 14.1 mg/g in epididymal tissue and area under the concentration-time curve for 24 h (AUC24) of 68.5 mg h/ml in serum and 108.9 mg h/g in epididymal tissue. For STFX, the Cmax was 1.22 mg/ml in serum and 1.66 mg/g in epididymal tissue, and the AUC24 was 9.58 mg h/ml in serum and 13.1 mg h/g in epididymal tissue. Neither treatment-related adverse events nor postoperative urogenital infections were observed. Conclusions: The results of this study suggest that oral administration of LVFX 500 mg or STFX 100 mg achieves effective epididymal concentrations for treatment of epididymitis. © 2016 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.
Keywords: Levofloxacin Sitafloxacin Epididymitis Antimicrobial pharmacokinetics Urogenital tract infection
1. Introduction Acute epididymitis is a common infection in sexually active and older males [1]. Inappropriate treatment is associated with recurrence of epididymitis, development of chronic pain, and infertility [2]. The predominant pathogens in acute epididymitis are aerobic
* Corresponding author. 2-5-1, Shikata-cho, Kita-ku, Okayama, 700-8558, Japan. Fax: þ81 86 231 3986. E-mail address: [email protected] (K. Wada).
gram-negative bacilli (e.g., Escherichia coli and Klebsiella spp.), Enterococcus spp., nonfermenting gram-negative bacilli (e.g., Pseudomonas spp.), and sexually transmitted organisms (e.g., Neisseria gonorrhoeae and Chlamydia trachomatis) [3]. Recently, the increasing incidence of fluoroquinolone-resistant isolates of E. coli and N. gonorrhoeae has become a major problem in infection control [4]. To ensure effective antimicrobial therapy, an appropriate dosing regimen should be selected by estimating the therapeutic effect with a pharmacokinetic-pharmacodynamic (PK-PD)-based approach. However, the tissue distribution characteristics of levofloxacin (LVFX) and sitafloxacin (STFX) and their PK-
http://dx.doi.org/10.1016/j.jiac.2016.12.010 1341-321X/© 2016 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.
Please cite this article in press as: Sadahira T, et al., Clinical pharmacokinetics of oral levofloxacin and sitafloxacin in epididymal tissue, J Infect Chemother (2016), http://dx.doi.org/10.1016/j.jiac.2016.12.010
2
T. Sadahira et al. / J Infect Chemother xxx (2016) 1e4
PD characteristics in the epididymis have not been well characterized. The aims of this study were to investigate the distribution of LVFX and STFX in human epididymal tissue and to assess whether penetration into the epididymis exceeds the breakpoint minimum inhibitory concentration (MIC).
2.4. Linear regression analysis
2. Materials and methods
For each drug, serum concentrations were plotted against epididymal tissue concentrations. Linear regression analysis was performed with an unweighted least-squares analysis of the data, with a nonlinear least-squares program MULTI [7]. The specific gravity of epididymal tissue was defined as 1 (g ¼ ml).
2.1. Patients
2.5. Pharmacokinetic model analysis
Subjects were patients with prostate cancer who underwent orchiectomy for hormonal therapy at Okayama University Hospital and its related institutions in Japan. Participants were recruited between July 2012 and June 2014, and written informed consent was obtained from all study patients prior to enrollment. Subjects with active urogenital infection, a history of treatment with fluoroquinolones within one week, or renal failure (The mean estimated glomerular filtration rates < 30 ml/min/1.73 m2) were excluded.
For each drug, pharmacokinetic model analysis was performed with the MULTI program [7]. As a naive pooled data method, all concentration-time data for serum and epididymal tissue were fitted simultaneously to a one-compartment model with first-order absorption and elimination, where the absorption lag-time (Lag) and the partition coefficient between serum and epididymal tissue (KP) were added to better describe the data. The pharmacokinetic parameters measured were the following: absorption rate constant (Ka, h1), volume of distribution (Vd, l), clearance (Cl, l/h), bioavailability (F), Lag (h) and KP.
2.2. Drug administration and sample collection 3. Results Participants were administered a tablet of 500 mg LVFX (CRAVIT™ tablet, Daiichi Sankyo Co. Ltd., Tokyo, Japan) or 100 mg STFX (GRACEVIT™ tablet, Daiichi Sankyo Co. Ltd., Tokyo, Japan) orally 1 h before orchiectomy. Epididymises were immediately rinsed in physiological saline after orchiectomy, and 0.5 g epididymal tissue samples were excised and stored frozen at 60 C until measurement. Blood samples were planned to be collected at 3 time points: immediately after right orchiectomy, immediately after left orchiectomy, and 1 h after the end of surgery. Collected blood samples (3 ml) were centrifuged, and the serum (1.5 ml) was collected and stored at 60 C until analysis. 2.3. Measurement of LVFX and STFX concentrations in serum and epididymal tissue Concentrations of LVFX and STFX in serum and epididymal tissue were measured by high-performance liquid chromatography (HPLC) with modifications of reported methods [5,6]. For LVFX, epididymal tissue samples (0.5 g) were homogenized with an overhead mixer in four volumes (w/v) of phosphate buffer (pH 7.0), and centrifuged. The tissue homogenate supernatants or serum samples (100 ml each) were extracted with dichlormethane (1 ml). After vortex-mixing and centrifugation, the upper aqueous layer was aspirated with a micro vacuum pump, and the organic layer was directly transferred to a clean test tube without pipetting. The organic solvent was evaporated, and the residues were reconstituted with the mobile phase and then injected into an HPLC system (20 ml). The HPLC system employed a C18 column at 40 C and detected LVFX with a fluorescence detector at 295 nm for excitation and 440 nm for emission. The mobile phase consisted of a mixture of 10 mmol/l phosphate buffer (pH 3.0), acetonitrile and triethylamine (76:24:0.076 [v/v/v]) at a flow rate of 1 ml/min. The quantification limits for LVFX were 0.05 mg/ml and 0.2 mg/g in serum and epididymal tissue, respectively, and both calibration curves were linear up to 15 mg/ml and 50 mg/g, respectively. The interday and intraday accuracy and precision were within 10%. For STFX, the same measurement methods as those for LVFX were used, except that the mobile phase was 50 mmol/l phosphate buffer (pH 2.5) and acetonitrile (77:23 [v/v]), and the fluorescence detector was set at 281 nm for excitation and 440 nm for emission. The quantification ranges were 0.05e2 mg/ml and 0.05e5 mg/g in serum and epididymal tissue, respectively. The interday and intraday accuracy and precision were within 10%.
3.1. Patient characteristics Baseline characteristics of the 18 subjects (LVFX 500 mg, n ¼ 9; STFX 100 mg, n ¼ 9) are enrolled. Throughout the presentation of the results, individual parameters and means ± standard deviations (SDs) are given. The mean ages of the patients enrolled were 77.0 ± 4.0 years for LVFX and 77.5 ± 4.8 years for STFX, respectively. Their mean weights were 55.5 ± 6.9 kg and 62.2 ± 7.4 kg, respectively. The mean estimated glomerular filtration rates were 73.2 ± 8.1 ml/ min/1.73 m2 and 74.4 ± 13.0 ml/min/1.73 m2, respectively. There were no patients with active urogenital infection, a history of treatment with fluoroquinolones within one week, or renal failure. 3.2. Measurement of LVFX and STFX concentrations in serum and epididymal tissue The mean serum and epididymal tissue concentrations of LVFX were 3.97 ± 3.08 mg/ml and 5.88 ± 5.41 mg/g, respectively. The mean serum and epididymal tissue concentrations of STFX were 0.39 ± 0.31 mg/ml and 0.56 ± 0.47 mg/g, respectively. The mean ratio of the epididymal concentration to serum concentration (E/S ratio) was 1.48 ± 0.45 for LVFX and 1.54 ± 0.81 for STFX. 3.3. Linear regression analysis The relationship between the concentrations of LVFX and STFX in serum and epididymal tissue was examined by a regression analysis. Fig. 1 shows a strong relationship between the LVFX concentrations in both sites (R ¼ 0.941), and a strong relationship between the STFX concentrations in both sites (R ¼ 0.916). 3.4. Pharmacokinetic model analysis The pharmacokinetic parameters were estimated as Lag ¼ 1.07 h, Ka ¼ 0.360 h1, Vd/F ¼ 21.3 l, Cl/F ¼ 7.28 l/h, KP ¼ 1.59 for LVFX and Lag ¼ 0.993 h, Ka ¼ 0.363 h1, Vd/F ¼ 31.7 l, Cl/F ¼ 10.4 l/h, KP ¼ 1.36 for STFX. The simulated concentrations based on these pharmacokinetic parameters fit the corresponding observed concentrations (Fig. 2). For LVFX, the simulated curves estimated the following: maximum concentration (Cmax) ¼ 8.84 mg/ml in serum and 14.1 mg/ g in epididymal tissue and area under the concentration-time curve for 24 h (AUC24) ¼ 68.5 mg h/ml in serum and 108.9 mg h/g in
Please cite this article in press as: Sadahira T, et al., Clinical pharmacokinetics of oral levofloxacin and sitafloxacin in epididymal tissue, J Infect Chemother (2016), http://dx.doi.org/10.1016/j.jiac.2016.12.010
T. Sadahira et al. / J Infect Chemother xxx (2016) 1e4
3
Fig. 1. Relationships between levofloxacin (18 plots) and sitafloxacin (16 plots) concentrations in serum and epididymal tissue.
Fig. 2. Observed concentrations of levofloxacin (18 serum and 18 epididymal tissue samples) and sitafloxacin (16 serum and 16 epididymal tissue samples) and simulated curves drawn based on the pharmacokinetic parameters for levofloxacin (Lag ¼ 1.07 h, Ka ¼ 0.360 h1, Vd/F ¼ 21.3 l, Cl/F ¼ 7.28 l/h, KP ¼ 1.59) and sitafloxacin (Lag ¼ 0.993 h, Ka ¼ 0.363 h1, Vd/F ¼ 31.7 l, Cl/F ¼ 10.4 l/h, KP ¼ 1.36).
epididymal tissue. Additionally, For STFX, estimates were Cmax ¼ 1.22 mg/ml in serum and 1.66 mg/g in epididymal tissue and AUC24 ¼ 9.58 mg h/ml in serum and 13.1 mg h/g in epididymal tissue. For antimicrobial effects of LVFX and STFX against pathogens, the simulated pharmacodynamics target values were shown in Table 1. 3.5. Adverse events Neither treatment-related adverse events nor postoperative urogenital infections were observed. 4. Discussion This study evaluated penetration of LVFX and STFX to noninflammatory epididymis and acceptable E/S ratios, Cmax and
AUC24 were observed by determining site-specific PK-PD characteristics. In the present study, the serum concentrations were in agreement with those found in previous studies [8,9]. The wide intersubject variation in the concentrations of LVFX and STFX found in serum and epididymal tissue in this study is common with other fluoroquinolones [10e12]. It is important to determine antimicrobial concentrations due to their site-specific concentrations and pharmacodynamic properties. Unfortunately, few studies have reported on the penetration of fluoroquinolones into human epididymal tissue, however, the present study had a limited number of cases, the penetration of LVFX and STFX into human epididymal tissue were similar to that previously reported [13] and the PK-PD characteristics of LVFX and STFX identified in this study seem to be significant.
Table 1 PK-PD parameters for LVFX and STFX in epididymal tissue. MIC (mg/mL)
LVFX
STFX
500 mg once daily
0.125 0.25 0.5 1 2 4
100 mg once daily
100 mg twice daily
200 mg once daily
AUC24/MIC
Cmax/MIC
AUC24/MIC
Cmax/MIC
AUC24/MIC
Cmax/MIC
AUC24/MIC
Cmax/MIC
871.3 435.6 217.8 108.9 54.46 27.23
112.6 56.3 28.1 14.1 7.04 3.52
104.4 52.2 26.1 13.1 6.53 3.26
13.29 6.64 3.32 1.66 0.83 0.42
200.5 100.3 50.1 25.1 12.5 6.27
14.76 7.38 3.69 1.85 0.92 0.46
208.9 104.4 52.2 26.1 13.1 6.53
26.6 13.3 6.64 3.32 1.66 0.83
Please cite this article in press as: Sadahira T, et al., Clinical pharmacokinetics of oral levofloxacin and sitafloxacin in epididymal tissue, J Infect Chemother (2016), http://dx.doi.org/10.1016/j.jiac.2016.12.010
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T. Sadahira et al. / J Infect Chemother xxx (2016) 1e4
Antimicrobial treatment should be directed against the specific etiological agent suspected on initial evaluation. Sometimes, case history, results of urine cultures or serum antibody titers may indicate an epididymitis [14]. Although further studies about clinical pharmacokinetics of other antimicrobials in human epididymal tissue should be investigated, the results of this study suggest that fluoroquinolones such as LVFX and STFX may be considered potentially valuable options in the treatment of epididymitis as is recommended by guidelines in Japan [15]. Regarding PK-PD parameters for efficacy of fluoroquinolones, Uegami et al. [16] reported that estimated values of fluoroquinolones against gram-negative rods should be 100 in AUC24/ MIC and 8 in Cmax/MIC. According to their results and our simulation shown in Table 1, LVFX 500 mg once daily regimens is enough effective for pathogens which LVFX MIC is less than 2 mg/mL, and STFX 100 mg once daily is enough effective only for pathogens which MIC is less than 0.25 mg/mL. The breakpoint MIC of LVFX for Enterobacteriaceae (which includes E. coli, Klebsiella, Enterobacter, Citrobacter, Serratia and Proteus spp.) in the Clinical and Laboratory Standards Institute (CLSI) [17] is 4 and that of STFX is not written. In the present study, the results indicate that LVFX and STFX might be not enough effective for bacterial epididymitis caused by pathogens with lower MIC than breakpoint MIC. However, it should be noted that the patients in this study were uninfected. LVFX and STFX concentrations in serum and epididymal tissue should depend on the presence and extent of epididymitis. A previous study suggested that penetration into rat epididymal tissue was dependent on vascular permeability associated with inflammation, and that the concentration of antibiotic amdinocillin was significantly higher at the site of inflammation [18]. This suggests the possibility that the PK-PD characteristics identified in this study may underestimate the epididymal concentrations and possibly the therapeutic effect of LVFX and STFX regimens for epididymitis. Thus, oral administration of LVFX 500 mg or STFX 100 mg achieves effective epididymal concentrations for treatment of epididymitis. However, a higher dose of STFX regimen would be recommended for epididymitis to exceed the breakpoint MIC. There are some limitations in this study. First, the number of enrolled patients was 9 per agent, and young patients or patients with severe renal failure such as dialysis patients were not enrolled. Second, we might be better to collect blood samples at elimination phase for exact evaluation in terms of pharmacokinetics; 6e8 h after the start of operation shown in Fig. 2. Third, epididymal tissues were uninfected and non-inflammatory. Ideally, we should assess epididymal tissue from patients with epididymitis, however, that is clinically difficult. Fourth, epididymal tissue used in this study included little epididymal fluid. Epididymitis is caused as retrograde infection and initial step of epididymitis is infection and inflammation in the ducts of epididymis. Namely, our results cannot apply to epididymal fluid as an initial infectious center. In conclusion, we investigated the penetration of LVFX and STFX into human non-inflammatory epididymal tissue in this study. Our results suggest that oral administration of LVFX 500 mg or STFX 100 mg achieves effective epididymal concentrations for treatment of epididymitis and these results are helpful for developing rational optimized dosing regimens for epididymitis based on acceptable tissue PD characteristics related to the MIC of the target agents. Ethical approval This clinical study was approved by the Okayama University Institutional Review Board prior to study initiation (Registration no. 1409).
Funding This work was not supported by any company.
Conflict of interest None to declare.
Acknowledgments The authors thank all of the investigators who contributed to this study.
References [1] Redshaw JD, Tran TL, Walis MC, deVries CR. Epididymitis. a 21-year retrospective review of presentations to an outpatient urology clinic. J Urol 2014;192:1203e7. [2] Costa P, Desclaux d'Arramon F, Gouby A, Navratil H, Geny F, Galtier M, et al. Disposition of roxithromycin in the epididymis after repeated oral administration. J Antimicrob Chemother 1992;30:197e201. [3] Pilatz A, Hossain H, Kaiser R, Mankertz A, Schuttler CG, Domann E, et al. Acute epididymitis revisited: impact of molecular diagnostics on etiology and contemporary guideline recommendations. Eur Urol 2015;68:428e35. [4] Wada K, Uehara S, Yamamoto M, Sadahira T, Mitsuhata R, Araki M, et al. Clinical analysis of bacterial strain profiles isolated from urinary tract infections: a 30-year study. J Infect Chemother 2016;22:478e82. [5] Zhou ZL, Yang M, Yu XY, Peng HY, Shan ZX, Chen SZ, et al. A rapid and simple high-performance liquid chromatography method for the determination of human plasma levofloxacin concentration and its application to bioequivalence studies. Biomed Chromatogr 2007;21:1045e51. [6] Aoki H, Ohshima Y, Tanaka M, Okazaki O, Hakusui H. High-performance liquid chromatographic determination of the new quinolone antibacterial agent DU6859a in human serum and urine using solid-phase extraction with photolysis-fluorescence detection. J Chromatogr B Biomed Appl 1994;660: 365e74. [7] Yamaoka K, Tanigawara Y, Nakagawa T, Uno T. A pharmacokinetic analysis program (multi) for microcomputer. J Pharmacobiodyn 1981;4:879e85. [8] Sadahira T, Wada K, Uehara S, Yamamoto M, Yamamoto M, Mitsuhata R, et al. Investigation for penetration of single-dose levofloxacin 500 mg in prostate tissue. Jpn J Chemother 2015;63:406e10. [9] Nakashima M, Uematsu T, Kosuge K, Umemura K, Hakusui H, Tanaka M. Pharmacokinetics and tolerance of DU-6859a, a new fluoroquinolone, after single and multiple oral doses in healthy volunteers. Antimicrob Agents Chemother 1995;39:170e4. [10] Stass H, Kubitza D. Pharmacokinetics and elimination of moxifloxacin after oral and intravenous administration in man. J Antimicrob Chemother 1999;43:83e90. [11] Niki Y. Pharmacokinetics and safety assessment of tosufloxacin tosilate. J Infect Chemother 2002;8:1e18. [12] Tanigawara Y, Nozawa K, Tsuda H. Optimal dose finding of garenoxacin based on population pharmacokinetics/pharmacodynamics and Monte Carlo simulation. Eur J Clin Pharmacol 2012;68:39e53. [13] Blondin C, Costa P, Bressolle F, Navratil H, Galtier M. Norfloxacin concentrations in plasma and human epididymal tissue after repeated administration. J Antimicrob Chemother 1991;27:392e4. [14] Lorenzo L, Rogel R, Sanchez-Gonzalez JV, Perez-Ardavin J, Moreno E, Lujan S, et al. Evaluation of adult scrotum in the emergency room: clinical characteristics, diagnosis, management, and costs. Urology 2016;94:36e41. [15] JAID/JSC Guide to Clinical Management of Infectious Diseases Committee, editor. The JAID/JSC guide to clinical management of infectious diseases 2014: XI urogenital infections. Tokyo: Life Science Publishing Co., Ltd.; 2014. p. 203e28. [16] Uegami S, Ikawa K, Ohge H, Nakashima A, Shigemoto N, Morikawa N, et al. Pharmacokinetics and pharmacodynamic target attainment of intravenous pazufloxacin in the bile of patients undergoing biliary pancreatic surgery. J Chemother 2014;26:287e92. [17] CLSI. Performance standards for antimicrobial susceptibility testing: 24th informational supplement. CLSI document M100-S24. Wayne, PA: Clinical and Laboratory Standards Institute; 2014. [18] See WA, Taylor TO, Mack LA, Tartaglione TA, Opheim KE, Berger RE. Bacterial epididymitis in the rat: a model for assessing the impact of acute inflammation on epididymal antibiotic penetration. J Urol 1990;144:780e4.
Please cite this article in press as: Sadahira T, et al., Clinical pharmacokinetics of oral levofloxacin and sitafloxacin in epididymal tissue, J Infect Chemother (2016), http://dx.doi.org/10.1016/j.jiac.2016.12.010
Contents lists available at ScienceDirect
Journal of Infection and Chemotherapy journal homepage: http://www.elsevier.com/locate/jic
Original Article
Clinical pharmacokinetics of oral levofloxacin and sitafloxacin in epididymal tissue Takuya Sadahira a, b, Koichiro Wada a, b, *, Kazuro Ikawa c, Norifumi Morikawa c, Hiroaki Kurahashi b, d, Takashi Yoshioka a, b, Yuichi Ariyoshi a, b, Yasuyuki Kobayashi a, b, Motoo Araki a, b, Ayano Ishii a, b, Masami Watanabe a, b, Shinya Uehara b, e, Toyohiko Watanabe a, b, Yasutomo Nasu a, b a
Department of Urology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1, Shikata-cho, Kita-ku, Okayama, 700-8558, Japan b Okayama Urological Research Group (OURG), 2-5-1, Shikata-cho, Kita-ku, Okayama, 700-8558, Japan c Department of Clinical Pharmacotherapy, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Hiroshima, 734-8551, Japan d Department of Urology, Tsukazaki Hospital, 68-1, Waku, Aboshi-ku, Himeji, 671-1227, Japan e Department of Urology, Kawasaki Medical School, 577, Matsushima, Kurashiki, 701-0114, Japan
a r t i c l e i n f o
a b s t r a c t
Article history: Received 18 August 2016 Received in revised form 31 October 2016 Accepted 19 December 2016 Available online xxx
Objectives: This study aimed to investigate the penetration of fluoroquinolones into human epididymal tissue. Methods: The penetration of levofloxacin (LVFX) 500 mg or sitafloxacin (STFX) 100 mg into epididymal tissue was examined. Patients with prostate cancer who were referred for orchiectomy were included. LVFX 500 mg (n ¼ 9) or STFX 100 mg (n ¼ 9) was administered orally 1 h before orchiectomy, and 0.5 g of epididymal tissue and blood samples were collected simultaneously during surgery. Drug concentrations were measured by high-performance liquid chromatography, and patient characteristics and adverse events were analyzed. Results: The mean ratio of the epididymal concentration to the serum concentration was 1.48 ± 0.45 for LVFX and 1.54 ± 0.81 for STFX. For LVFX, the simulated curves estimated the following: maximum concentrations (Cmax) of 8.84 mg/ml in serum and 14.1 mg/g in epididymal tissue and area under the concentration-time curve for 24 h (AUC24) of 68.5 mg h/ml in serum and 108.9 mg h/g in epididymal tissue. For STFX, the Cmax was 1.22 mg/ml in serum and 1.66 mg/g in epididymal tissue, and the AUC24 was 9.58 mg h/ml in serum and 13.1 mg h/g in epididymal tissue. Neither treatment-related adverse events nor postoperative urogenital infections were observed. Conclusions: The results of this study suggest that oral administration of LVFX 500 mg or STFX 100 mg achieves effective epididymal concentrations for treatment of epididymitis. © 2016 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.
Keywords: Levofloxacin Sitafloxacin Epididymitis Antimicrobial pharmacokinetics Urogenital tract infection
1. Introduction Acute epididymitis is a common infection in sexually active and older males [1]. Inappropriate treatment is associated with recurrence of epididymitis, development of chronic pain, and infertility [2]. The predominant pathogens in acute epididymitis are aerobic
* Corresponding author. 2-5-1, Shikata-cho, Kita-ku, Okayama, 700-8558, Japan. Fax: þ81 86 231 3986. E-mail address: [email protected] (K. Wada).
gram-negative bacilli (e.g., Escherichia coli and Klebsiella spp.), Enterococcus spp., nonfermenting gram-negative bacilli (e.g., Pseudomonas spp.), and sexually transmitted organisms (e.g., Neisseria gonorrhoeae and Chlamydia trachomatis) [3]. Recently, the increasing incidence of fluoroquinolone-resistant isolates of E. coli and N. gonorrhoeae has become a major problem in infection control [4]. To ensure effective antimicrobial therapy, an appropriate dosing regimen should be selected by estimating the therapeutic effect with a pharmacokinetic-pharmacodynamic (PK-PD)-based approach. However, the tissue distribution characteristics of levofloxacin (LVFX) and sitafloxacin (STFX) and their PK-
http://dx.doi.org/10.1016/j.jiac.2016.12.010 1341-321X/© 2016 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.
Please cite this article in press as: Sadahira T, et al., Clinical pharmacokinetics of oral levofloxacin and sitafloxacin in epididymal tissue, J Infect Chemother (2016), http://dx.doi.org/10.1016/j.jiac.2016.12.010
2
T. Sadahira et al. / J Infect Chemother xxx (2016) 1e4
PD characteristics in the epididymis have not been well characterized. The aims of this study were to investigate the distribution of LVFX and STFX in human epididymal tissue and to assess whether penetration into the epididymis exceeds the breakpoint minimum inhibitory concentration (MIC).
2.4. Linear regression analysis
2. Materials and methods
For each drug, serum concentrations were plotted against epididymal tissue concentrations. Linear regression analysis was performed with an unweighted least-squares analysis of the data, with a nonlinear least-squares program MULTI [7]. The specific gravity of epididymal tissue was defined as 1 (g ¼ ml).
2.1. Patients
2.5. Pharmacokinetic model analysis
Subjects were patients with prostate cancer who underwent orchiectomy for hormonal therapy at Okayama University Hospital and its related institutions in Japan. Participants were recruited between July 2012 and June 2014, and written informed consent was obtained from all study patients prior to enrollment. Subjects with active urogenital infection, a history of treatment with fluoroquinolones within one week, or renal failure (The mean estimated glomerular filtration rates < 30 ml/min/1.73 m2) were excluded.
For each drug, pharmacokinetic model analysis was performed with the MULTI program [7]. As a naive pooled data method, all concentration-time data for serum and epididymal tissue were fitted simultaneously to a one-compartment model with first-order absorption and elimination, where the absorption lag-time (Lag) and the partition coefficient between serum and epididymal tissue (KP) were added to better describe the data. The pharmacokinetic parameters measured were the following: absorption rate constant (Ka, h1), volume of distribution (Vd, l), clearance (Cl, l/h), bioavailability (F), Lag (h) and KP.
2.2. Drug administration and sample collection 3. Results Participants were administered a tablet of 500 mg LVFX (CRAVIT™ tablet, Daiichi Sankyo Co. Ltd., Tokyo, Japan) or 100 mg STFX (GRACEVIT™ tablet, Daiichi Sankyo Co. Ltd., Tokyo, Japan) orally 1 h before orchiectomy. Epididymises were immediately rinsed in physiological saline after orchiectomy, and 0.5 g epididymal tissue samples were excised and stored frozen at 60 C until measurement. Blood samples were planned to be collected at 3 time points: immediately after right orchiectomy, immediately after left orchiectomy, and 1 h after the end of surgery. Collected blood samples (3 ml) were centrifuged, and the serum (1.5 ml) was collected and stored at 60 C until analysis. 2.3. Measurement of LVFX and STFX concentrations in serum and epididymal tissue Concentrations of LVFX and STFX in serum and epididymal tissue were measured by high-performance liquid chromatography (HPLC) with modifications of reported methods [5,6]. For LVFX, epididymal tissue samples (0.5 g) were homogenized with an overhead mixer in four volumes (w/v) of phosphate buffer (pH 7.0), and centrifuged. The tissue homogenate supernatants or serum samples (100 ml each) were extracted with dichlormethane (1 ml). After vortex-mixing and centrifugation, the upper aqueous layer was aspirated with a micro vacuum pump, and the organic layer was directly transferred to a clean test tube without pipetting. The organic solvent was evaporated, and the residues were reconstituted with the mobile phase and then injected into an HPLC system (20 ml). The HPLC system employed a C18 column at 40 C and detected LVFX with a fluorescence detector at 295 nm for excitation and 440 nm for emission. The mobile phase consisted of a mixture of 10 mmol/l phosphate buffer (pH 3.0), acetonitrile and triethylamine (76:24:0.076 [v/v/v]) at a flow rate of 1 ml/min. The quantification limits for LVFX were 0.05 mg/ml and 0.2 mg/g in serum and epididymal tissue, respectively, and both calibration curves were linear up to 15 mg/ml and 50 mg/g, respectively. The interday and intraday accuracy and precision were within 10%. For STFX, the same measurement methods as those for LVFX were used, except that the mobile phase was 50 mmol/l phosphate buffer (pH 2.5) and acetonitrile (77:23 [v/v]), and the fluorescence detector was set at 281 nm for excitation and 440 nm for emission. The quantification ranges were 0.05e2 mg/ml and 0.05e5 mg/g in serum and epididymal tissue, respectively. The interday and intraday accuracy and precision were within 10%.
3.1. Patient characteristics Baseline characteristics of the 18 subjects (LVFX 500 mg, n ¼ 9; STFX 100 mg, n ¼ 9) are enrolled. Throughout the presentation of the results, individual parameters and means ± standard deviations (SDs) are given. The mean ages of the patients enrolled were 77.0 ± 4.0 years for LVFX and 77.5 ± 4.8 years for STFX, respectively. Their mean weights were 55.5 ± 6.9 kg and 62.2 ± 7.4 kg, respectively. The mean estimated glomerular filtration rates were 73.2 ± 8.1 ml/ min/1.73 m2 and 74.4 ± 13.0 ml/min/1.73 m2, respectively. There were no patients with active urogenital infection, a history of treatment with fluoroquinolones within one week, or renal failure. 3.2. Measurement of LVFX and STFX concentrations in serum and epididymal tissue The mean serum and epididymal tissue concentrations of LVFX were 3.97 ± 3.08 mg/ml and 5.88 ± 5.41 mg/g, respectively. The mean serum and epididymal tissue concentrations of STFX were 0.39 ± 0.31 mg/ml and 0.56 ± 0.47 mg/g, respectively. The mean ratio of the epididymal concentration to serum concentration (E/S ratio) was 1.48 ± 0.45 for LVFX and 1.54 ± 0.81 for STFX. 3.3. Linear regression analysis The relationship between the concentrations of LVFX and STFX in serum and epididymal tissue was examined by a regression analysis. Fig. 1 shows a strong relationship between the LVFX concentrations in both sites (R ¼ 0.941), and a strong relationship between the STFX concentrations in both sites (R ¼ 0.916). 3.4. Pharmacokinetic model analysis The pharmacokinetic parameters were estimated as Lag ¼ 1.07 h, Ka ¼ 0.360 h1, Vd/F ¼ 21.3 l, Cl/F ¼ 7.28 l/h, KP ¼ 1.59 for LVFX and Lag ¼ 0.993 h, Ka ¼ 0.363 h1, Vd/F ¼ 31.7 l, Cl/F ¼ 10.4 l/h, KP ¼ 1.36 for STFX. The simulated concentrations based on these pharmacokinetic parameters fit the corresponding observed concentrations (Fig. 2). For LVFX, the simulated curves estimated the following: maximum concentration (Cmax) ¼ 8.84 mg/ml in serum and 14.1 mg/ g in epididymal tissue and area under the concentration-time curve for 24 h (AUC24) ¼ 68.5 mg h/ml in serum and 108.9 mg h/g in
Please cite this article in press as: Sadahira T, et al., Clinical pharmacokinetics of oral levofloxacin and sitafloxacin in epididymal tissue, J Infect Chemother (2016), http://dx.doi.org/10.1016/j.jiac.2016.12.010
T. Sadahira et al. / J Infect Chemother xxx (2016) 1e4
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Fig. 1. Relationships between levofloxacin (18 plots) and sitafloxacin (16 plots) concentrations in serum and epididymal tissue.
Fig. 2. Observed concentrations of levofloxacin (18 serum and 18 epididymal tissue samples) and sitafloxacin (16 serum and 16 epididymal tissue samples) and simulated curves drawn based on the pharmacokinetic parameters for levofloxacin (Lag ¼ 1.07 h, Ka ¼ 0.360 h1, Vd/F ¼ 21.3 l, Cl/F ¼ 7.28 l/h, KP ¼ 1.59) and sitafloxacin (Lag ¼ 0.993 h, Ka ¼ 0.363 h1, Vd/F ¼ 31.7 l, Cl/F ¼ 10.4 l/h, KP ¼ 1.36).
epididymal tissue. Additionally, For STFX, estimates were Cmax ¼ 1.22 mg/ml in serum and 1.66 mg/g in epididymal tissue and AUC24 ¼ 9.58 mg h/ml in serum and 13.1 mg h/g in epididymal tissue. For antimicrobial effects of LVFX and STFX against pathogens, the simulated pharmacodynamics target values were shown in Table 1. 3.5. Adverse events Neither treatment-related adverse events nor postoperative urogenital infections were observed. 4. Discussion This study evaluated penetration of LVFX and STFX to noninflammatory epididymis and acceptable E/S ratios, Cmax and
AUC24 were observed by determining site-specific PK-PD characteristics. In the present study, the serum concentrations were in agreement with those found in previous studies [8,9]. The wide intersubject variation in the concentrations of LVFX and STFX found in serum and epididymal tissue in this study is common with other fluoroquinolones [10e12]. It is important to determine antimicrobial concentrations due to their site-specific concentrations and pharmacodynamic properties. Unfortunately, few studies have reported on the penetration of fluoroquinolones into human epididymal tissue, however, the present study had a limited number of cases, the penetration of LVFX and STFX into human epididymal tissue were similar to that previously reported [13] and the PK-PD characteristics of LVFX and STFX identified in this study seem to be significant.
Table 1 PK-PD parameters for LVFX and STFX in epididymal tissue. MIC (mg/mL)
LVFX
STFX
500 mg once daily
0.125 0.25 0.5 1 2 4
100 mg once daily
100 mg twice daily
200 mg once daily
AUC24/MIC
Cmax/MIC
AUC24/MIC
Cmax/MIC
AUC24/MIC
Cmax/MIC
AUC24/MIC
Cmax/MIC
871.3 435.6 217.8 108.9 54.46 27.23
112.6 56.3 28.1 14.1 7.04 3.52
104.4 52.2 26.1 13.1 6.53 3.26
13.29 6.64 3.32 1.66 0.83 0.42
200.5 100.3 50.1 25.1 12.5 6.27
14.76 7.38 3.69 1.85 0.92 0.46
208.9 104.4 52.2 26.1 13.1 6.53
26.6 13.3 6.64 3.32 1.66 0.83
Please cite this article in press as: Sadahira T, et al., Clinical pharmacokinetics of oral levofloxacin and sitafloxacin in epididymal tissue, J Infect Chemother (2016), http://dx.doi.org/10.1016/j.jiac.2016.12.010
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T. Sadahira et al. / J Infect Chemother xxx (2016) 1e4
Antimicrobial treatment should be directed against the specific etiological agent suspected on initial evaluation. Sometimes, case history, results of urine cultures or serum antibody titers may indicate an epididymitis [14]. Although further studies about clinical pharmacokinetics of other antimicrobials in human epididymal tissue should be investigated, the results of this study suggest that fluoroquinolones such as LVFX and STFX may be considered potentially valuable options in the treatment of epididymitis as is recommended by guidelines in Japan [15]. Regarding PK-PD parameters for efficacy of fluoroquinolones, Uegami et al. [16] reported that estimated values of fluoroquinolones against gram-negative rods should be 100 in AUC24/ MIC and 8 in Cmax/MIC. According to their results and our simulation shown in Table 1, LVFX 500 mg once daily regimens is enough effective for pathogens which LVFX MIC is less than 2 mg/mL, and STFX 100 mg once daily is enough effective only for pathogens which MIC is less than 0.25 mg/mL. The breakpoint MIC of LVFX for Enterobacteriaceae (which includes E. coli, Klebsiella, Enterobacter, Citrobacter, Serratia and Proteus spp.) in the Clinical and Laboratory Standards Institute (CLSI) [17] is 4 and that of STFX is not written. In the present study, the results indicate that LVFX and STFX might be not enough effective for bacterial epididymitis caused by pathogens with lower MIC than breakpoint MIC. However, it should be noted that the patients in this study were uninfected. LVFX and STFX concentrations in serum and epididymal tissue should depend on the presence and extent of epididymitis. A previous study suggested that penetration into rat epididymal tissue was dependent on vascular permeability associated with inflammation, and that the concentration of antibiotic amdinocillin was significantly higher at the site of inflammation [18]. This suggests the possibility that the PK-PD characteristics identified in this study may underestimate the epididymal concentrations and possibly the therapeutic effect of LVFX and STFX regimens for epididymitis. Thus, oral administration of LVFX 500 mg or STFX 100 mg achieves effective epididymal concentrations for treatment of epididymitis. However, a higher dose of STFX regimen would be recommended for epididymitis to exceed the breakpoint MIC. There are some limitations in this study. First, the number of enrolled patients was 9 per agent, and young patients or patients with severe renal failure such as dialysis patients were not enrolled. Second, we might be better to collect blood samples at elimination phase for exact evaluation in terms of pharmacokinetics; 6e8 h after the start of operation shown in Fig. 2. Third, epididymal tissues were uninfected and non-inflammatory. Ideally, we should assess epididymal tissue from patients with epididymitis, however, that is clinically difficult. Fourth, epididymal tissue used in this study included little epididymal fluid. Epididymitis is caused as retrograde infection and initial step of epididymitis is infection and inflammation in the ducts of epididymis. Namely, our results cannot apply to epididymal fluid as an initial infectious center. In conclusion, we investigated the penetration of LVFX and STFX into human non-inflammatory epididymal tissue in this study. Our results suggest that oral administration of LVFX 500 mg or STFX 100 mg achieves effective epididymal concentrations for treatment of epididymitis and these results are helpful for developing rational optimized dosing regimens for epididymitis based on acceptable tissue PD characteristics related to the MIC of the target agents. Ethical approval This clinical study was approved by the Okayama University Institutional Review Board prior to study initiation (Registration no. 1409).
Funding This work was not supported by any company.
Conflict of interest None to declare.
Acknowledgments The authors thank all of the investigators who contributed to this study.
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Please cite this article in press as: Sadahira T, et al., Clinical pharmacokinetics of oral levofloxacin and sitafloxacin in epididymal tissue, J Infect Chemother (2016), http://dx.doi.org/10.1016/j.jiac.2016.12.010