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Faggion PI, Isoton G, Possa E, Tasso L. Is the penetration of clindamycin into the masseter muscle really enough to treat odontogenic infections? Clin Oral Investig 2020; 25:3257-3266. [PMID: 33128135 DOI: 10.1007/s00784-020-03656-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Accepted: 10/20/2020] [Indexed: 11/25/2022]
Abstract
OBJECTIVES This study aims to determine the penetration of clindamycin into the masseter muscle of rats by microdialysis and correlate with the main microorganisms involved in odontogenic infections. MATERIALS AND METHODS Tissue concentrations of clindamycin in healthy muscle tissue were measured by microdialysis after administration of a single intravenous dose of 51 mg/kg and multiple doses of 17 mg/kg (8/8 h). It was quantified in plasma after a single administration of 51 mg/kg. Microdialysis samples were collected at 30-min intervals and clindamycin was assayed by LC-MS. Pharmacokinetic parameters and tissue penetration were determined. Pharmacokinetic/pharmacodynamic index (ƒ%T > minimum inhibitory concentration (MIC)) was considered to assess dosing regimens. RESULTS The pharmacokinetic parameters determined by non-compartmental plasma analysis for the dose of 51 mg/kg were similar to that determined by compartmental analysis. The maximum free interstitial concentration (Cmax) of clindamycin in muscle tissue was 14.20 (10.63-14.89) and 4.82 (3.35-6.66) mg/L for 51 mg/kg and 17 mg/kg 8/8 h, respectively. In addition, the area under the curve (AUC0-inf) for plasma and tissue of clindamycin were 44.78 (28.82-65.65) and 16.54 (13.83-18.35) h.mg/L for 51 mg/kg, respectively, and the tissue penetration factor determined was 1.10. Considering that the main bacteria that cause odontogenic infections generally present MIC ≤ 0.5 mg/L, the ƒ%T > MIC index is reached when the dose regimen of 17 mg/kg 8/8 h is employed. CONCLUSIONS This investigation showed that clindamycin excellently penetrates muscle tissue of rats. It provides effective antibacterial concentrations at the target site when 17 mg/kg 8/8 h is employed and can be applied to treat the main bacteria causing odontogenic infections. CLINICAL RELEVANCE It reinforces the use of clindamycin in odontogenic infections with significant tissue penetration.
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Affiliation(s)
- Paula I Faggion
- Laboratory of Pharmacokinetics, Health Sciences Postgraduate Program, University of Caxias do Sul, Caxias do Sul, Rio Grande do Sul, Brazil
| | - Gabriela Isoton
- College of Pharmacy, University of Caxias do Sul, Caxias do Sul, Rio Grande do Sul, Brazil
| | - Eduarda Possa
- College of Pharmacy, University of Caxias do Sul, Caxias do Sul, Rio Grande do Sul, Brazil
| | - Leandro Tasso
- Laboratory of Pharmacokinetics, Health Sciences Postgraduate Program, University of Caxias do Sul, Caxias do Sul, Rio Grande do Sul, Brazil.
- College of Pharmacy, University of Caxias do Sul, Caxias do Sul, Rio Grande do Sul, Brazil.
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2
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Chen C, Zhou H, Guan C, Zhang H, Li Y, Jiang X, Dong Z, Tao Y, Du J, Wang S, Zhang T, Du N, Guo J, Wu Y, Song Z, Luan H, Wang Y, Du H, Zhang S, Li C, Chang H, Wang T. Applicability of free drug hypothesis to drugs with good membrane permeability that are not efflux transporter substrates: A microdialysis study in rats. Pharmacol Res Perspect 2020; 8:e00575. [PMID: 32266794 PMCID: PMC7138916 DOI: 10.1002/prp2.575] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 02/10/2020] [Accepted: 02/10/2020] [Indexed: 12/16/2022] Open
Abstract
In clinical pharmacology, the free drug hypothesis has been widely applied in the interpretation of the relationship between pharmacokinetics and pharmacodynamics (PK/PD). The free drug hypothesis assumes that the unbound drug concentration in blood is the same as that in the site of action at steady state. The objective of this study is to demonstrate whether the free drug hypothesis is universally applicable for all drugs. The unbound concentrations of the 18 compounds in blood and in brain interstitial fluids (ISF) at steady state following constant intravenous infusion were simultaneously monitored up to 6 hours via in vivo microdialysis technique. Based on the permeability and efflux ratio (ER), the test compounds can be divided into two classes. Class I includes the compounds with good membrane permeability that are not substrates of efflux transporters (eg, P-gp, BCRP, and MRPs), whereas Class II includes the compounds that are substrates of efflux transporters. The steady-state unbound drug concentrations in blood, brain, and CSF are quantitatively very similar for Class I compounds, whereas the steady-state unbound concentrations in the brain and CSF are significantly lower than those in blood for Class II compounds. These results strongly suggest that the free drug hypothesis is not universal for all drugs but is only applicable for drugs with good permeability that are not substrates of efflux transporters.
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Affiliation(s)
- Chun Chen
- Drug Metabolism and Pharmacokinetics (DMPK) DepartmentPharmaronBeijingChina
| | - Hongyu Zhou
- Drug Metabolism and Pharmacokinetics (DMPK) DepartmentPharmaronBeijingChina
| | - Chi Guan
- Drug Metabolism and Pharmacokinetics (DMPK) DepartmentPharmaronBeijingChina
| | - Huanhuan Zhang
- Drug Metabolism and Pharmacokinetics (DMPK) DepartmentPharmaronBeijingChina
| | - Yingying Li
- Drug Metabolism and Pharmacokinetics (DMPK) DepartmentPharmaronBeijingChina
| | - Xue Jiang
- Drug Metabolism and Pharmacokinetics (DMPK) DepartmentPharmaronBeijingChina
| | - Zheng Dong
- Drug Metabolism and Pharmacokinetics (DMPK) DepartmentPharmaronBeijingChina
| | - Yuanyuan Tao
- Drug Metabolism and Pharmacokinetics (DMPK) DepartmentPharmaronBeijingChina
| | - Juan Du
- Drug Metabolism and Pharmacokinetics (DMPK) DepartmentPharmaronBeijingChina
| | - Shuyao Wang
- Drug Metabolism and Pharmacokinetics (DMPK) DepartmentPharmaronBeijingChina
| | - Teng Zhang
- Drug Metabolism and Pharmacokinetics (DMPK) DepartmentPharmaronBeijingChina
| | - Na Du
- Drug Metabolism and Pharmacokinetics (DMPK) DepartmentPharmaronBeijingChina
| | - Junyang Guo
- Drug Metabolism and Pharmacokinetics (DMPK) DepartmentPharmaronBeijingChina
| | - Yaqiong Wu
- Drug Metabolism and Pharmacokinetics (DMPK) DepartmentPharmaronBeijingChina
| | - Zehai Song
- Drug Metabolism and Pharmacokinetics (DMPK) DepartmentPharmaronBeijingChina
| | - Haofei Luan
- Drug Metabolism and Pharmacokinetics (DMPK) DepartmentPharmaronBeijingChina
| | - Yu Wang
- Drug Metabolism and Pharmacokinetics (DMPK) DepartmentPharmaronBeijingChina
| | - Hongwen Du
- Drug Metabolism and Pharmacokinetics (DMPK) DepartmentPharmaronBeijingChina
| | - Shaofeng Zhang
- Drug Metabolism and Pharmacokinetics (DMPK) DepartmentPharmaronBeijingChina
| | - Chen Li
- Drug Metabolism and Pharmacokinetics (DMPK) DepartmentPharmaronBeijingChina
| | - Hang Chang
- Drug Metabolism and Pharmacokinetics (DMPK) DepartmentPharmaronBeijingChina
| | - Tao Wang
- Drug Metabolism and Pharmacokinetics (DMPK) DepartmentPharmaronBeijingChina
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3
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Tomas A, Stilinović N, Sabo A, Tomić Z. Use of microdialysis for the assessment of fluoroquinolone pharmacokinetics in the clinical practice. Eur J Pharm Sci 2019; 131:230-242. [PMID: 30811969 DOI: 10.1016/j.ejps.2019.02.032] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 02/22/2019] [Accepted: 02/22/2019] [Indexed: 12/12/2022]
Abstract
Antibacterial drugs, including fluoroquinolones, can exert their therapeutic action only with adequate penetration at the infection site. Multiple factors, such as rate of protein binding, drug liposolubility and organ blood-flow all influence ability of antibiotics to penetrate target tissues. Microdialysis is an in vivo sampling technique that has been successfully applied to measure the distribution of fluoroquinolones in the interstitial fluid of different tissues both in animal studies and clinical setting. Tissue concentrations need to be interpreted within the context of the pathogenesis and causative agents implicated in infections. Integration of microdialysis -derived tissue pharmacokinetics with pharmacodynamic data offers crucial information for correlating exposure with antibacterial effect. This review explores these concepts and provides an overview of tissue concentrations of fluoroquinolones derived from microdialysis studies and explores the therapeutic implications of fluoroquinolone distribution at various target tissues.
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Affiliation(s)
- Ana Tomas
- Department of Pharmacology, Toxicology and Clinical Pharmacology, Faculty of Medicine, University of Novi Sad, Serbia.
| | - Nebojša Stilinović
- Department of Pharmacology, Toxicology and Clinical Pharmacology, Faculty of Medicine, University of Novi Sad, Serbia
| | - Ana Sabo
- Department of Pharmacology, Toxicology and Clinical Pharmacology, Faculty of Medicine, University of Novi Sad, Serbia
| | - Zdenko Tomić
- Department of Pharmacology, Toxicology and Clinical Pharmacology, Faculty of Medicine, University of Novi Sad, Serbia
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4
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Loryan I, Hoppe E, Hansen K, Held F, Kless A, Linz K, Marossek V, Nolte B, Ratcliffe P, Saunders D, Terlinden R, Wegert A, Welbers A, Will O, Hammarlund-Udenaes M. Quantitative Assessment of Drug Delivery to Tissues and Association with Phospholipidosis: A Case Study with Two Structurally Related Diamines in Development. Mol Pharm 2017; 14:4362-4373. [PMID: 29099189 DOI: 10.1021/acs.molpharmaceut.7b00480] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Drug induced phospholipidosis (PLD) may be observed in the preclinical phase of drug development and pose strategic questions. As lysosomes have a central role in pathogenesis of PLD, assessment of lysosomal concentrations is important for understanding the pharmacokinetic basis of PLD manifestation and forecast of potential clinical appearance. Herein we present a systematic approach to provide insight into tissue-specific PLD by evaluation of unbound intracellular and lysosomal (reflecting acidic organelles) concentrations of two structurally related diprotic amines, GRT1 and GRT2. Their intratissue distribution was assessed using brain and lung slice assays. GRT1 induced PLD both in vitro and in vivo. GRT1 showed a high intracellular accumulation that was more pronounced in the lung, but did not cause cerebral PLD due to its effective efflux at the blood-brain barrier. Compared to GRT1, GRT2 revealed higher interstitial fluid concentrations in lung and brain, but more than 30-fold lower lysosomal trapping capacity. No signs of PLD were seen with GRT2. The different profile of GRT2 relative to GRT1 is due to a structural change resulting in a reduced basicity of one amino group. Hence, by distinct chemical modifications, undesired lysosomal trapping can be separated from desired drug delivery into different organs. In summary, assessment of intracellular unbound concentrations was instrumental in delineating the intercompound and intertissue differences in PLD induction in vivo and could be applied for identification of potential lysosomotropic compounds in drug development.
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Affiliation(s)
- Irena Loryan
- Translational PKPD Group, Department of Pharmaceutical Biosciences, Associate member of SciLifeLab, Uppsala University , 751 24 Uppsala, Sweden
| | | | | | - Felix Held
- Fraunhofer-Chalmers Centre, Chalmers Science Park , 412 88 Gothenburg, Sweden.,Department of Mathematical Sciences, Chalmers University of Technology and University of Gothenburg , 412 96 Gothenburg, Sweden
| | | | | | | | | | | | | | | | | | | | - Olaf Will
- Grünenthal GmbH , 52099 Aachen, Germany
| | - Margareta Hammarlund-Udenaes
- Translational PKPD Group, Department of Pharmaceutical Biosciences, Associate member of SciLifeLab, Uppsala University , 751 24 Uppsala, Sweden
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5
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Composition and Function of the Interstitial Fluid. Protein Sci 2016. [DOI: 10.1201/9781315374307-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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6
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Kitamura A, Okura T, Higuchi K, Deguchi Y. Cocktail-Dosing Microdialysis Study to Simultaneously Assess Delivery of Multiple Organic–Cationic Drugs to the Brain. J Pharm Sci 2016; 105:935-940. [DOI: 10.1002/jps.24691] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Revised: 09/17/2015] [Accepted: 09/25/2015] [Indexed: 12/22/2022]
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7
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Katsube T, Yano Y, Wajima T, Yamano Y, Takano M. Pharmacokinetic/pharmacodynamic modeling and simulation to determine effective dosage regimens for doripenem. J Pharm Sci 2010; 99:2483-91. [PMID: 19904828 DOI: 10.1002/jps.21997] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The aim of this study was to obtain information on effective dosage regimens of doripenem by a modeling and simulation approach based on pharmacokinetic (PK)/pharmacodynamic (PD) theory. The PK/PD model we have already developed was modified to explain in vitro bactericidal kinetics of doripenem for several Pseudomonas aeruginosa strains. Time-course profiles of bacterial counts in patients infected with P. aeruginosa were simulated for typical clinical dosage regimens in Japan considering the variability of PK and the patients' backgrounds by a Monte Carlo simulation. Moreover, time-course profiles of probability achieving the criterion (log(CFU/mL) < 0) were predicted for the evaluation of antibacterial efficacy by renal function. The in vitro bacterial profiles at various dosage regimens could be well explained by the PK/PD model. The simulations suggested the dependence of antibacterial efficacy on the frequency of administration, indicating time-dependent antibacterial activity. It was also suggested that 500 mg t.i.d. showed significant bacterial reduction in patients for any degree of renal function and any severities in 2 weeks after the start of treatment. Our approach to simulate time-course profiles of bacterial counts should be useful for determining and examining effective dosage regimens, including the treatment period, in drug development.
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Affiliation(s)
- Takayuki Katsube
- Clinical Research Department, Shionogi & Co., Ltd, Sagisu 5-12-4, Fukushima-ku, Osaka 553-0002, Japan.
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8
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Okura T, Ozawa T, Ito Y, Kimura M, Kagawa Y, Yamada S. Enhancement by grapefruit juice of morphine antinociception. Biol Pharm Bull 2009; 31:2338-41. [PMID: 19043223 DOI: 10.1248/bpb.31.2338] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The aim of this study was to investigate the effect of grapefruit juice intake on the antinociception of morphine in rats. The antinociception of morphine (30 mg/kg, per os (p.o.)) was significantly enhanced by the oral administration of grapefruit juice (2 ml/rat). Further, the effect of grapefruit juice was examined in morphine-tolerant rats. The repeated administration of morphine (100 mg/kg p.o.) for 5 d caused a marked decrease in the antinociception, indicating the development of morphine-tolerance. In the morphine-tolerant rats, oral administration of grapefruit juice potentiated significantly the antinociceptive effect of morphine. To examine the pharmacokinetics of morphine after the repeated treatment with morphine for 5 d, microdialysis probes were implanted into the jugular vein and spinal intrathecal space in rats. The morphine concentrations in the blood and intrathecal cerebrospinal fluid (CSF) were gradually decreased by the repeated treatment with morphine. The grapefruit juice treatment significantly increased the blood concentration of morphine in morphine-tolerant rats. These results suggest that oral administration of grapefruit juice enhances the morphine antinociception by increasing the intestinal absorption of this agent.
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Affiliation(s)
- Takashi Okura
- Department of Pharmacokinetics and Pharmacodynamics and Global Center of Excellence and Clinical Pharmaceutics, School of Pharmaceutical Sciences, University of Shizuoka, Japan
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9
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Katsube T, Yano Y, Yamano Y, Munekage T, Kuroda N, Takano M. Pharmacokinetic-pharmacodynamic modeling and simulation for bactericidal effect in an in vitro dynamic model. J Pharm Sci 2008; 97:4108-17. [PMID: 18314887 DOI: 10.1002/jps.21265] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A pharmacokinetic (PK)/pharmacodynamic (PD) modeling strategy to explain the data from an in vitro dynamic model is proposed. Two carbapenem antibiotics, doripenem and meropenem, and three Pseudomonas aeruginosa strains were used as example drugs and strains. The PD model we originally developed to explain the in vitro time-kill data was modified by incorporating bactericidal activities and simulated in vivo PK profiles of the drugs. By employing only one parameter regarding the bactericidal activity from the data at a certain dosage regimen, the bacterial profiles at various dosage regimens could be well simulated for both antibiotics by the PK/PD model. Moreover, simulated bacterial counts for various dosage regimens correlated with time above minimum inhibitory concentration derived from free drug concentrations (fT > MIC) for doripenem. The predicted fT > MIC values to achieve PK/PD endpoints for three strains (static effect: 25.0%, 23.9%, and 39.8%, 2-log killing effect: 28.1%, 29.5%, and 49.6%, 90% maximum killing effect: 36.5%, 46.8%, and 80.7%) were similar to those estimated from free drug concentrations in animal infection models. The proposed in vitro PK/PD model would be useful for simulating bactericidal kinetics in the dynamic model and predicting the human therapeutic target for PK/PD indices estimated from animal infection models.
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10
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Katsube T, Yamano Y, Yano Y. Pharmacokinetic–Pharmacodynamic Modeling and Simulation for in Vivo Bactericidal Effect in Murine Infection Model. J Pharm Sci 2008; 97:1606-14. [PMID: 17705288 DOI: 10.1002/jps.21062] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
A pharmacokinetic (PK)/pharmacodynamic (PD) modeling strategy to simulate in vivo bactericidal effects for three carbapenem antibiotics, doripenem (DRPM), meropenem (MEPM)/cilastatin (CS), and imipenem (IPM)/CS, against a Pseudomonas aeruginosa (P. aeruginosa) strain is proposed. The PD model we have already developed to explain in vitro time-kill profiles was modified to incorporate the growth rate, bactericidal activities, and PK profiles in murine lung infection models. Plasma concentration data and bacterial time-kill data for each antibiotic consist of six and eight time points, respectively, at one dose regimen (four or five mouse/point). In vivo time-kill curves could be well simulated for each antibiotic by the PK/PD model. Simulated bacterial counts at 24 h and PK/PD indices derived from total drug concentrations (time above the minimum inhibitory concentration (MIC) (T > MIC), C(max)/MIC, and AUC/MIC) for various dose regimens were examined for MEPM/CS and IPM/CS. Simulated bacterial counts correlated only with T > MIC (correlation coefficient: 0.951 for MEPM/CS, 0.982 for IPM/CS) and T > MIC values to achieve a bacteriostatic effect and a 2-log killing effect for both antibiotics were estimated to be approximately 15 and 20%, respectively, which are similar to previously reported results. These findings suggested that the proposed PK/PD model is a good tool for predicting in vivo bactericidal effects.
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Affiliation(s)
- Takayuki Katsube
- Biostatistics Department, Shionogi & Co., Ltd., Sagisu 5-12-4, Fukushima-ku, Osaka 553-0002, Japan
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11
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Aoki M, Iguchi M, Hayashi H, Suzuki H, Shibasaki S, Kurosawa T, Hayashi M. Proposal of Membrane Transport Mechanism of Protein-Unbound Ulifloxacin into Epithelial Lining Fluid Determined by Improved Microdialysis. Biol Pharm Bull 2008; 31:1773-7. [DOI: 10.1248/bpb.31.1773] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Makoto Aoki
- Applied Pharmacology Research Laboratories, Pharmaceutical Research Center, Meiji Seika Kaisha, Ltd
| | - Maki Iguchi
- Applied Pharmacology Research Laboratories, Pharmaceutical Research Center, Meiji Seika Kaisha, Ltd
| | - Hiroyuki Hayashi
- Applied Pharmacology Research Laboratories, Pharmaceutical Research Center, Meiji Seika Kaisha, Ltd
| | - Hisashi Suzuki
- Applied Pharmacology Research Laboratories, Pharmaceutical Research Center, Meiji Seika Kaisha, Ltd
| | - Shigeki Shibasaki
- Applied Pharmacology Research Laboratories, Pharmaceutical Research Center, Meiji Seika Kaisha, Ltd
| | - Tohru Kurosawa
- Applied Pharmacology Research Laboratories, Pharmaceutical Research Center, Meiji Seika Kaisha, Ltd
| | - Masahiro Hayashi
- School of Pharmacy, Tokyo University of Pharmacy and Life Sciences
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12
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Yu LJ, Chen Y, Treadway JL, McPherson RK, McCoid SC, Gibbs EM, Hoover DJ. Establishment of Correlation between in Vitro Enzyme Binding Potency and in Vivo Pharmacological Activity: Application to Liver Glycogen Phosphorylase a Inhibitors. J Pharmacol Exp Ther 2006; 317:1230-7. [PMID: 16537796 DOI: 10.1124/jpet.105.100545] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In drug discovery, establishing a correlation between in vitro potency and in vivo activity is critical for the validation of the selected target and for developing confidence in the in vitro screening strategy. The present study developed a competition equilibrium dialysis assay using a 96-well dialysis technique to determine the intrinsic Kd for 13 inhibitors of human liver glycogen phosphorylase a (GPa) in the presence of liver homogenate to mimic the physiological environment. The results provided evidence that binding of an inhibitor to GPa was affected by extra cofactors present in the liver homogenate. A good correlation was demonstrated between the in vitro Kd determined under liver homogenate environment and free liver concentration of an inhibitor at the minimum efficacious dose in diabetic ob/ob mice. This study revealed important elements (such as endogenous cofactors missing from the in vitro assay and free concentration at the target tissue) that contributed to a better understanding of the linkage between in vitro and in vivo activity. The approach developed here may be applied to many drugs in pharmacology studies in which the correlation between in vitro and in vivo activities for the target tissue (such as solid tumors, brain, and liver) is critical.
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Affiliation(s)
- Li J Yu
- Department of Pharmacokinetics, Groton Laboratories, Pfizer Global Research & Development, Pfizer Inc., Groton, Connecticut, USA.
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13
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Zeitlinger M, Müller M, Joukhadar C. Lung microdialysis--a powerful tool for the determination of exogenous and endogenous compounds in the lower respiratory tract (mini-review). AAPS JOURNAL 2005; 7:E600-8. [PMID: 16353939 PMCID: PMC2751264 DOI: 10.1208/aapsj070362] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In vivo measurement of concentrations of drugs and endogenous substances at the site of action has become a primary focus of research. In this context the minimal invasive microdialysis (MD) technique has been increasingly employed for the determination of pharmacokinetics in lung. Although lung MD is frequently employed to investigate various drugs and endogenous substances, the majority of lung MD studies were performed to determine the pharmacokinetic profile of antimicrobials that can be related to the importance of respiratory tract infections. For the lower respiratory tract various methods, such as surgical collection of whole lung tissue and bonchoalveolar lavage (BAL), are currently available for the determination of pharmacokinetics of antimicrobials. Head-to-head comparison of pharmacokinetics of antibiotics in lung revealed high differences between MD and conventional methods. MD might be regarded as a more advantageous approach because of its higher anatomical resolution and the ability to obtain dynamic time-vs-concentration profiles within one subject. However, due to ethical objections lung MD is limited to animals or patients undergoing elective thoracic surgery. From these studies it was speculated that the concentrations in healthy lung tissue may be predicted reasonably by the measurement of concentrations in skeletal muscle tissue. However, until now this was only demonstrated for beta-lactam antibiotics and needs to be confirmed for other classes of antimicrobials. In conclusion, the present review shows that MD is a promising method for the determination of antimicrobials in the lung, but might also be applicable for measuring a wide range of other drugs and for the investigation of metabolism in the lower respiratory tract.
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Affiliation(s)
- Markus Zeitlinger
- Department of Clinical Pharmacology, Division of Clinical Pharmacokinetics, Medical University of Vienna, Austria.
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14
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Marchand S, Dahyot C, Lamarche I, Mimoz O, Couet W. Microdialysis study of imipenem distribution in skeletal muscle and lung extracellular fluids of noninfected rats. Antimicrob Agents Chemother 2005; 49:2356-61. [PMID: 15917533 PMCID: PMC1140500 DOI: 10.1128/aac.49.6.2356-2361.2005] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The aim of this study was to investigate the imipenem distribution in muscle and lung interstitial fluids by microdialysis in rats and to compare the free concentrations in tissue with the free concentrations in blood. Microdialysis probes were inserted into the jugular vein, hind leg muscle, and lung. Imipenem recoveries in these three media were determined in each rat by retrodialysis by drug period before drug administration. Imipenem was infused intravenously at a dose of 120 mg . kg-1 over 30 min, and microdialysis samples were collected for 150 min. The whole study was conducted with nonhydrated rats (n=4) and hydrated rats (n=6) while the animals were under isoflurane anesthesia. The decay of free concentrations in blood, muscle, and lung with time were monoexponential; and the concentration profiles in these three media were virtually superimposed in both groups. Accordingly, the ratios of the area under the curve (AUC) for tissue (muscle or lung) to the AUC for blood were always virtually equal to 1. Compared to values previously determined with awake rats, clearance was reduced by 2 and 1.5 in nonhydrated and hydrated rats, respectively, but the volume of distribution was unchanged. By combining microdialysis in blood and tissues, it was possible to demonstrate that free imipenem concentrations were virtually identical in blood, muscle, and lung.
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Affiliation(s)
- Sandrine Marchand
- EA 3809, Faculté de Médecine et de Pharmacie, Poitiers Cedex, France
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15
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Plock N, Kloft C. Microdialysis—theoretical background and recent implementation in applied life-sciences. Eur J Pharm Sci 2005; 25:1-24. [PMID: 15854796 DOI: 10.1016/j.ejps.2005.01.017] [Citation(s) in RCA: 181] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2004] [Revised: 01/20/2005] [Accepted: 01/21/2005] [Indexed: 11/26/2022]
Abstract
In the past decade microdialysis has become a method of choice in the study of unbound tissue concentrations of both endogenous and exogenous substances. Microdialysis has been shown to offer information about substances directly at the site of action while being well tolerable and safe. The large variety of its field of application has been demonstrated. However, a few challenges have to be met to make this method generally applicable in routine applications. This review will provide an overview over theoretical aspects that have to be considered during the implementation of microdialysis. Moreover, a comparison between microdialysis and other tissue sampling techniques will demonstrate advantages and limitations of the methods mentioned. Subsequently, it will present a critical synopsis of a variety of scientific/biomedical applications of this method with emphasis on the most recent literature, focussing on target tissues while giving examples of substances examined. It is concluded that microdialysis will be of great value in future investigations of pharmacokinetics, pharmacodynamics and in monitoring of disease status and progression.
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Affiliation(s)
- Nele Plock
- Department of Clinical Pharmacy, Institute of Pharmacy, Freie Universitaet Berlin, Kelchstr. 31, D-12169 Berlin, Germany
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16
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Deguchi Y, Sun J, Tauchi Y, Sakai S, Morimoto K. Distribution characteristics of grepafloxacin, a fluoroquinolone antibiotic, in lung epithelial lining fluid and alveolar macrophage. Drug Metab Pharmacokinet 2005; 18:319-26. [PMID: 15618751 DOI: 10.2133/dmpk.18.319] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The purpose of this study was to investigate the distribution of Grepafloxacin (GPFX), a new quinolone antimicrobial agent, in the lung epithelial lining fluid (ELF) and the alveolar macrophage (AM) in rats, which are potential infection sites in respiratory tract infections. We also aimed to clarify the mechanism governing the transferability of GPFX into the alveolus compartment from a kinetic point of view. The AUC ratios of ELF/plasma and AM/plasma after the oral administration of GPFX were 5.69 +/- 1.00 and 352 +/- 57, respectively, which were several-fold greater than those of ciprofloxacin (CPFX). Pharmacokinetic analyses of time profiles of GPFX concentrations in ELF and AM revealed that the influx clearance from plasma to ELF across the alveolar barrier is 5-fold greater than the efflux clearance from ELF. In addition, the permeability of GPFX across the cultured AM cell membrane was 7-fold and 11-fold greater than that of levofloxacin (LVFX) and CPFX, respectively. The extent of intracellular binding to AM cells (expressed as a constant (alpha)) was the greatest for GPFX, followed by CPFX and LVFX. There was a significant correlation between the alpha value and the partitioning to the immobilized artificial membrane (IAM) column, which consists of phospholipid residues covalently bound to silica. These results suggest that GPFX is highly distributed in ELF and AM, and that the high transferability of GPFX into ELF may be attributable to the existence of asymmetrical transport across the alveolar barrier. In addition, it was suggested that both rapid permeability across the AM cell membrane and avid binding to the membrane phospholipids may be responsible for the high accumulation of GPFX in AM.
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Affiliation(s)
- Yoshiharu Deguchi
- Department of Pharmaceutics, Hokkaido College of Pharmacy, Otaru, Japan
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17
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Müller M, dela Peña A, Derendorf H. Issues in pharmacokinetics and pharmacodynamics of anti-infective agents: distribution in tissue. Antimicrob Agents Chemother 2004; 48:1441-53. [PMID: 15105091 PMCID: PMC400530 DOI: 10.1128/aac.48.5.1441-1453.2004] [Citation(s) in RCA: 190] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- Markus Müller
- Health Science Center, Department of Pharmaceutics, College of Pharmacy, University of Florida, Gainesville, Florida 32610-0494, USA
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18
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Ezzine S, Yamaguchi N, Varin F. Determination of interstitial rocuronium concentrations in the muscle tissue of anesthetized dogs by microdialysis. J Pharmacol Toxicol Methods 2004; 49:121-9. [PMID: 14990337 DOI: 10.1016/j.vascn.2003.08.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2003] [Accepted: 08/06/2003] [Indexed: 11/17/2022]
Abstract
INTRODUCTION The objective was to establish and validate a microdialysis technique for the quantification of interstitial concentrations of the neuromuscular blocker, rocuronium, in the muscle tissue of dogs under steady-state conditions. METHODS The standard and combined retrodialysis approaches were used for in vivo microdialysis probe calibration. After induction of anesthesia with pentobarbital (30 mg/kg), the left femoral vein was cannulated and blood drawn for protein binding determination. Microdialysis probes were inserted in the muscle and calibrated in vivo, using vecuronium as the calibrator. Each dog received a short 2-min infusion followed by a 120-min infusion of rocuronium via the right jugular vein and three microdialysis samples were collected at steady-state during a 2-h period. Samples were stored at -70 degrees C until HPLC analysis. RESULTS Using combined retrodialysis, rocuronium unbound interstitial (C(ISFu)) and venous plasma (C(pssuv)) concentrations are in good agreement; with a ratio C(ISFu)/C(pssuv) of 100+/-11%. Using standard retrodialysis, this ratio was 47+/-7%. CONCLUSIONS Combined retrodialysis is a more reliable and accurate technique for quantitative assessment of rocuronium interstitial concentrations especially for lengthy anesthetic procedures. These findings have potential implications, as drug concentrations in the site of action would be more relevant for concentration-effect relation of muscle relaxants.
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Affiliation(s)
- Samia Ezzine
- Faculté de Pharmacie, Université de Montréal, 2900 Edouard Montpetit, CP 6128, succursale Centre-ville, Montreal, Quebec, Canada H3C 3 J7
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19
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Abstract
By incorporating the transporter-mediated or receptor-mediated transport process in physiologically based pharmacokinetic models, we succeeded in the quantitative prediction of plasma and tissue concentrations of beta-lactam antibiotics, insulin, pentazocine, quinolone antibacterial agents, and inaperizone and digoxin. The author's research on transporter-mediated pharmacokinetics focuses on the molecular and functional characteristics of drug transporters such as oligopeptide transporter, monocarboxylic acid transporter, anion antiporter, organic anion transporters, organic cation/carnitine transporters (OCTNs), and the ATP-binding cassette transporters P-glycoprotein and MRP2. We have successfully demonstrated that these transporters play important roles in the influxes and/or effluxes of drugs in intestinal and renal epithelial cells, hepatocytes, and brain capillary endothelial cells that form the blood-brain barrier. In the systemic carnitine deficiency (SCD) phenotype mouse model, juvenile visceral steatosis (jvs) mouse, a mutation in the OCTN2 gene was found. Furthermore, several types of mutation in human SCD patients were found, demonstrating that OCTN2 is a physiologically important carnitine transporter. Interestingly, OCTNs transport carnitine in a sodium-dependent manner and various cationic drugs transport it in a sodium-independent manner. OCTNs are thought to be multifunctional transporters for the uptake of carnitine into tissue cells and for the elimination of intracellular organic cationic drugs.
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Affiliation(s)
- Akira Tsuji
- Faculty of Pharmaceutical Sciences, Kanazawa University, 13-1 Takara-machi, Kanazawa 920-0934, Japan.
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20
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Freddo RJ, Dalla Costa T. Determination of norfloxacin free interstitial levels in skeletal muscle by microdialysis. J Pharm Sci 2002; 91:2433-40. [PMID: 12379929 DOI: 10.1002/jps.10230] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Tissue penetration and distribution of antibiotics are important issues when establishing antibiotic therapies. Free concentrations of antibiotics at the infection site are responsible for bacteria killing effect. The knowledge of the correlation between blood levels and tissue concentrations can be helpful for adequate dosing of these drugs. It was the aim of this study to investigate norfloxacin pharmacokinetics in rats to predict free interstitial levels of the drug, determined by microdialysis, using pharmacokinetic parameters derived from total plasma data. Norfloxacin free tissue and total plasma levels were determined in Wistar rats after administering 5 and 10 mg/kg i.v. bolus doses. Plasma and microdialysis samples were analyzed by high-performance liquid chromatography. Norfloxacin plasma pharmacokinetics was consistent with a two compartments model. A simultaneous fitting of plasma and tissue concentrations was performed using a proportionality factor because norfloxacin free tissue levels determined by microdialysis were lower than those predicted using plasma data. A similar proportionality (f(T)) factor was calculated by the computer program Scientist((R)) for both doses (0.25 +/- 0.08). It can be concluded that it is possible to predict concentration time profiles of norfloxacin in the peripheral compartment based on plasma data using the adequate tissue penetration factor.
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Affiliation(s)
- Rodrigo J Freddo
- Programa de Pós-Graduação em Ciĉncias Farmacêuticas, Faculdade de Farmácia, Universidade Federal do Rio Grande do Sul, Av. Ipiranga, 2752, Porto Alegre, Brazil
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21
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Deguchi Y. Application of In Vivo Brain Microdialysis to the Study of Blood-brain Barrier Transport of Drugs. Drug Metab Pharmacokinet 2002; 17:395-407. [PMID: 15618691 DOI: 10.2133/dmpk.17.395] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Recent advances in blood-brain barrier (BBB) research have led to a new understanding of drug transport processes at the BBB. The BBB acts as a dynamic regulatory interface at which nutrients necessary for neural activity are actively taken up into the brain from the blood circulation, and actively excludes metabolites that might interfere with the maintenance of brain homeostasis. Such influx and efflux transport functions at the BBB would also control the concentrations of various drugs in the brain interstitial fluid (ISF), which are an important determinant of the central nervous system (CNS) effects. Thus, direct measurement of the brain ISF concentration of drugs can provide significant information for clarifying the influx and efflux transport functions of drugs across the BBB. Although several experimental techniques have been developed to investigate transport functions across the BBB, in vivo brain microdialysis seems to be one of the most suitable techniques for characterizing the influx and efflux transport functions across the BBB under physiological and pathological conditions. This review covers studies during the past decade, in which the influx and efflux transport of drugs across the BBB was kinetically and mechanistically evaluated by means of the brain microdialysis technique. Some applications of brain microdialysis to studies on neuronal function and neurotherapeutics are also included.
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Affiliation(s)
- Yoshiharu Deguchi
- Department of Drug Disposition & Pharmacokinetics, School of Pharmaceutical Sciences, Teikyo University, Tsukui-gun, Kanagawa, Japan.
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Araki H, Ogake N, Tsuneda R, Minami S, Watanabe Y, Tamai I, Tsuji A. Muscle Distribution of Antimicrobial Agents after a Single Intravenous Administration to Rats. Drug Metab Pharmacokinet 2002; 17:237-44. [PMID: 15618675 DOI: 10.2133/dmpk.17.237] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The purpose of this study was to evaluate the distribution of three fluoroquinolones (pazufloxacin, ciprofloxacin and ofloxacin) and a beta-lactam, ceftazidime in the tissue interstitial and intracellular spaces after a single intravenous administration to rats based on muscle microdialysis. The unbound concentration in the tissue interstitial fluid (C(isf,u)) after administration was estimated from the concentration in the dialysate by muscle microdialysis, the in vitro permeability rate constant, and the previously reported effective dialysis coefficient. The C(isf,u)s of pazufloxacin, ciprofloxacin, ofloxacin and ceftazidime in the muscle were close to their unbound concentrations in the venous plasma. These results were consistent with ones previously obtained at steady state. Based on these results, the total concentration in the tissue interstitial fluid (C(isf)) was calculated from the ratio of plasma protein binding, the plasma concentration, and previously reported interstitial-to-plasma albumin ratio in muscle of rats. The calculated C(isf) was compared with the muscle concentration (C(m)) obtained using the homogenized tissue. The C(isf) of ceftazidime was higher than the C(m). The C(isf) of pazufloxacin was found to be almost equal to its C(m). The C(isf)s of ciprofloxacin and ofloxacin were lower than their C(m)s with the exception of the values at 5 min after administration. These results indicate that ceftazidime is mainly distributed in the interstitial space of the muscle, that pazufloxacin is distributed equally in both the interstitial space and the tissue cells, and that ciprofloxacin and ofloxacin are mainly distributed in the tissue cells rather than the interstitial space.
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Affiliation(s)
- Harumi Araki
- Research Laboratories, Toyama Chemical Co., Ltd., Japan.
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23
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De La Peña A, Dalla Costa T, Talton JD, Rehak E, Gross J, Thyroff-Friesinger U, Webb AI, Müller M, Derendorf H. Penetration of cefaclor into the interstitial space fluid of skeletal muscle and lung tissue in rats. Pharm Res 2001; 18:1310-4. [PMID: 11683245 DOI: 10.1023/a:1013042128791] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
PURPOSE To measure and compare the penetration of cefaclor from the plasma compartment into the interstitial space of lung and skeletal muscle in rats and to integrate the data in a pharmacokinetic model. METHODS Unbound interstitial concentrations in muscle and lung were measured by in vivo microdialysis following i.v. bolus doses of 50 and 75 mg/kg cefaclor. Unbound muscle concentrations were also measured after a primed, continuous i.v. infusion at an infusion rate of 0.3 mg/kg/min. RESULTS The cefaclor half-life in plasma, muscle and lung was approximately 1 h. Unbound cefaclor concentrations in muscle and lung were found to be virtually identical. A 2-compartment body model was fitted to the data with a tissue penetration factor (AUC(tissue(unbound)))/AUC(plasma(unbound))) of approximately 0.26 independent of dose, tissue and mode of administration. CONCLUSIONS Unbound concentrations of cefaclor in the interstitial space fluid of lung and skeletal muscle are of similar magnitude and lower than those in plasma. Using total plasma concentrations would overestimate the antibacterial activity of the drug and therefore its clinical efficacy. Instead, therapeutically active levels of cefaclor at the site of action should be taken into account. Microdialysis allows direct measurement of these unbound concentrations.
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Affiliation(s)
- A De La Peña
- University of Florida, College of Pharmacy, Department of Pharmaceutics, Gainesville 32610, USA
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24
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Abstract
The objective of this review is to survey the recent literature regarding the applications of microdialysis in pharmacokinetic studies and facilitating many other studies in peripheral tissues such as muscle, subcutaneous adipose tissue, heart, lung, etc. It has been reported extensively that microdialysis is a useful technique for monitoring free concentrations of compounds in extracellular fluid (ECF), and it is gaining popularity in pharmacokinetic and pharmacodynamic studies, both in experimental animals and humans. The first part of this review discusses the use of microdialysis technique for ECF sampling in peripheral tissues in animal studies. The second part of the review describes the use of microdialysis for ECF sampling in peripheral tissues in human studies. Microdialysis has been applied extensively to measure both endogenous and exogenous compounds in ECF. Of particular benefit is the fact that microdialysis measures the unbound concentrations in the peripheral tissue fluid which have been shown to be responsible for the pharmacological effects. With the increasing number of applications of microdialysis, it is obvious that this method will have an important place in studying drug pharmacokinetics and pharmacodynamics.
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Affiliation(s)
- A de la Peña
- 100494 College of Pharmacy, University of Florida, Gainesville, FL 32610-0494, USA
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25
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Deguchi Y, Yokoyama Y, Sakamoto T, Hayashi H, Naito T, Yamada S, Kimura R. Brain distribution of 6-mercaptopurine is regulated by the efflux transport system in the blood-brain barrier. Life Sci 2000; 66:649-62. [PMID: 10794520 DOI: 10.1016/s0024-3205(99)00637-2] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
6-mercaptopurine (6-MP) has been used clinically for 40 years to maintain remission in patients with acute lymphoblastic leukemia (ALL). However, central nervous system (CNS) relapses frequently occur in patients with ALL who continuously receive anticancer drugs, including 6-MP, during remission maintenance therapy. The cause of such CNS relapse is not well understood. One possible reason may involve the restricted distribution of 6-MP in the brain. This study, therefore, investigates the blood-brain barrier (BBB) transport which largely regulates 6-MP distribution in the brain using a quantitative microdialysis technique and centers on the efflux transport of 6-MP across the BBB. The brain tissue, cerebrospinal fluid (CSF), or hippocampal interstitial fluid (ISF) concentration of 6-MP was very low compared with the unbound plasma concentration, suggesting that 6-MP distribution in the brain is highly restricted. Kinetic analyses of this BBB transport showed that the efflux clearance from brain ISF to plasma across the BBB (CLout) is approximately 20-times greater than the influx clearance from plasma to brain (CLin). The CLout was significantly reduced by 1mM N-ethylmaleimide (NEM), a sulfhydryl-modifying agent, suggesting the participation of transport protein in the efflux of 6-MP across the BBB. In addition, efflux transport was inhibited by an intracerebral infusion of probenecid (1.5 mM), p-aminohippuric acid (PAH, 3.0 mM), benzoate (3.6 mM), or salicylate (3.7 mM) administered through a microdialysis probe, but neither choline (0.8 mM) nor tetraethylammonium (TEA, 0.7 mM) had any effect. These data suggest that the restricted 6-MP brain distribution may be ascribed to efficient efflux from the brain, possibly via both the organic anion transport system, shared with probenecid and PAH, and the monocarboxylic acid transport system, shared with benzoate and salicylate.
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Affiliation(s)
- Y Deguchi
- Department of Biopharmacy, School of Pharmaceutical Sciences, University of Shizuoka, Japan.
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26
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Abstract
The role played by efflux transport systems across the blood-brain barrier (BBB) in the disposition of xenobiotics in the brain is described. Several drugs and organic anions are transported across the BBB via P-glycoprotein and other carrier-mediated efflux transport systems. Studies using in vitro cultured brain capillary endothelial cells, kinetic analysis, and mdr1a gene knock-out mice have shown that P-glycoprotein, located on the BBB, restricts the entry of vincristine and quinidine to the brain. Brain microdialysis studies have demonstrated that the brain interstitial fluid (ISF) concentrations of quinolone antibiotics are significantly lower than their corresponding unbound serum concentrations. A distributed model analysis supports the finding that efflux transport systems on the BBB restrict distribution of 3'-azido-3'-deoxythymidine (AZT), 2',3'-dideoxyinosine (DDI), and quinolone antibiotics. A brain efflux index (BEI) method has been developed to provide direct evidence of an efflux transport system for carrying substrates from the cerebrum to the circulating blood across the BBB. The BEI method revealed the existence of carrier-mediated efflux organic anion transport systems for compounds such as p-aminohippuric acid, AZT, DDI, taurocholic acid, BQ-123, and estron sulfate. Moreover, cerebral neurotransmitters such as gamma-aminobutyric acid, L-glutamic acid, and L-aspartic acid are transported from brain to the circulating blood in the intact form via a carrier-mediated efflux transport system. The BBB not only restricts nonspecific permeation from the circulating blood to the brain, but also functions as an active efflux transport system for xenobiotics. Accordingly, the BBB plays a very important role by pumping xenobiotics and some endogenous compounds out of the brain, acting as a central nervous system (CNS)-specific detoxifying system supporting and maintaining normal cerebral function.
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Oldner A, Goiny M, Rudehill A, Ungerstedt U, Sollevi A. Tissue hypoxanthine reflects gut vulnerability in porcine endotoxin shock. Crit Care Med 1999; 27:790-7. [PMID: 10321671 DOI: 10.1097/00003246-199904000-00037] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To study differences in organ sensitivity during progressive endotoxin shock tissue levels of hypoxanthine, used as an indicator of adenosine triphosphate depletion and cellular energy failure, were monitored simultaneously in several organs by in vivo microdialysis. DESIGN Prospective, controlled animal study. SETTING University research laboratory. SUBJECTS Seventeen landrace pigs. MEASUREMENTS AND MAIN RESULTS Tissue levels of hypoxanthine, assessed by in vivo microdialysis, were monitored (in the ileum, liver, lung, skeletal muscle, subcutaneous fat, and arterial blood) simultaneously in addition to central hemodynamics during endotoxin shock in ten pigs. Seven sham animals not receiving endotoxin served as controls. Marked changes were seen in central hemodynamic parameters in response to endotoxemia. Very prominent increases were seen in the ileum and liver, followed by the lung, whereas only limited changes were observed in subcutaneous fat. These results indicate a differentiated development of cellular energy failure in response to endotoxemia in different organs. By considering the high amounts of xanthine oxidase seen in the gut, the increases in hypoxanthine may provide an important substrate for reactive oxygen species formation in this organ. The limited changes seen in subcutaneous fat suggest that this tissue may provide limited sensitivity when monitoring the septic patient. CONCLUSIONS These findings support the concept of specific vulnerability of the gut during endotoxemia.
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Affiliation(s)
- A Oldner
- Department of Anesthesiology and Intensive Care, Karolinska Hospital, Stockholm, Sweden
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28
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Müller M, Brunner M, Schmid R, Putz EM, Schmiedberger A, Wallner I, Eichler HG. Comparison of three different experimental methods for the assessment of peripheral compartment pharmacokinetics in humans. Life Sci 1998; 62:PL227-34. [PMID: 9566779 DOI: 10.1016/s0024-3205(98)00071-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In many cases the concentration reached in a peripheral effect compartment rather than in plasma determines the clinical outcome of therapy. Therefore, several experimental approaches have been developed for direct assessment of drug kinetics in peripheral compartments. Particularly saliva sampling, skin blister fluid sampling, and in vivo microdialysis are frequently employed for measuring peripheral drug concentrations. However, data derived from these techniques have never been directly compared. In the present study, the tissue kinetics of theophylline were measured following single dose administration simultaneously in cantharides induced skin blisters, saliva and microdialysates of subcutaneous- and skeletal muscle- tissue and compared to plasma concentrations. Theophylline was administered to 9 healthy volunteers as an i.v. infusion of 240 mg. Mean ratio (AUCsaliva/AUCplasma) was 0.63 +/- 0.05, mean ratio (AUCblister/AUCplasma) was 0.69 +/- 0.12, mean ratio (AUCmuscle/AUCplasma) was 0.41 +/- 0.10, mean ratio (AUCsubcutaneous/AUCplasma) was 0.34 +/- 0.07. The time course of the concentration(peripheral)/concentration(plasma)-ratios showed that tissue concentrations obtained by microdialysis were closely correlated to free plasma levels, whereas saliva- and cantharides blister data overestimated the corresponding free plasma concentrations. It is concluded that microdialysis represents a reliable technique for the measurement of unbound peripheral compartment concentrations and is superior to saliva- and skin blister concentration measurements.
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Affiliation(s)
- M Müller
- Department of Clinical Pharmacology, University of Vienna Medical School, Austria.
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Müller M, Rohde B, Kovar A, Georgopoulos A, Eichler HG, Derendorf H. Relationship between serum and free interstitial concentrations of cefodizime and cefpirome in muscle and subcutaneous adipose tissue of healthy volunteers measured by microdialysis. J Clin Pharmacol 1997; 37:1108-13. [PMID: 9506005 DOI: 10.1002/j.1552-4604.1997.tb04294.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Microdialysis is a suitable method to monitor unbound concentrations of antimicrobial drugs in the interstitial tissue space which is the site of many infections. The aim of this investigation was to examine whether free tissue levels of cefodizime (81% plasma protein binding) and cefpirome (10% plasma protein binding) in muscle and subcutaneous adipose tissue of healthy volunteers obtained by microdialysis are consistent with the extent of their respective plasma protein binding. Healthy volunteers were given cefodizine and cefpirome at a single intravenous 2-g dose in a randomized crossover design. Microdialysis probes were inserted into a medial vastus muscle and into the periumbilical subcutaneous layer. After calibration of the probe, samples of serum and microdialysis fluid were obtained and drug concentrations were measured using a microagar diffusion-bioassay. There was a reasonable agreement between plasma protein binding data and the tissue penetration of both cephalosporins (AUC0-infinity tissue, free/AUC0-infinity serum, total-ratios) into the interstitial fluid of the muscle tissue, but not for the subcutaneous tissue layer. Furthermore, the serum and tissue concentrations of both drugs were fitted to an open two-compartment body model. The measured free-tissue concentrations were compared with calculated unbound concentrations in the peripheral compartment. Good agreement was observed for the free muscle concentrations, but unbound concentrations in the subcutaneous tissue was somewhat higher (cefpirome) or lower (cefodizime) than predicted. This may be due to the different lipophilicities of the two compounds.
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Affiliation(s)
- M Müller
- Department of Clinical Pharmacology, Vienna University School of Medicine, Austria
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30
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Araki H, Ogake N, Minami S, Watanabe Y, Narita H, Tamai I, Tsuji A. Application of muscle microdialysis to evaluate the concentrations of the fluoroquinolones pazufloxacin and ofloxacin in the tissue interstitial fluids of rats. J Pharm Pharmacol 1997; 49:1141-4. [PMID: 9401953 DOI: 10.1111/j.2042-7158.1997.tb06057.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Muscle microdialysis has been used to determine the unbound concentrations of the fluoroquinolones, pazufloxacin and ofloxacin, in tissue interstitial fluids (Cisf,u) of rats under steady state conditions. Cisf,u was estimated from the concentration in dialysate and the in-vitro permeability rate constant by the extrapolation method based on the clearance concept. Paper-disks were inserted under the abdominal skin of rats, and the drug concentrations in the fluids penetrating into the disks (Cdisk) were measured and compared with Cisf,u. The Cisf,u of pazufloxacin and ofloxacin in muscle were close to their unbound concentrations in the venous plasma; these were 75.3% and 77.1%, respectively, of the total concentrations in plasma at the steady state. The Cdisk of pazufloxacin and ofloxacin were also close to their Cisf,u. These results indicate that the unbound concentrations of the fluoroquinolones in the tissue interstitial fluids were the same as those in the venous plasma. The disk insertion technique seems to be useful for evaluating drug concentrations in tissue interstitial fluid.
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Affiliation(s)
- H Araki
- Research Laboratories, Toyama Chemical Company Limited, Japan
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31
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Petersen LJ. Quantitative measurement of extracellular histamine concentrations in intact human skin in vivo by the microdialysis technique: methodological aspects. Allergy 1997; 52:547-55. [PMID: 9201366 DOI: 10.1111/j.1398-9995.1997.tb02598.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Calculation of recovery is needed in microdialysis studied to calculate absolute concentrations of compounds in the extracellular water space. The purposes of this study were to determine the extracellular concentration of histamine in intact human skin in vivo and to study the validity of absolute histamine measurements during allergic skin reactions. A skin microdialysis technique and two calibration techniques, the no net flux method and the flow rate method, were used to quantify histamine concentrations in resting skin. To validate these techniques, skin glucose concentrations were analysed as well. In addition, the influence of vasodilation and plasma extravasation on recovery was followed after intradermal injection of codeine, a mast-cell secretagogue. As expected, both calibration methods estimated skin glucose concentrations to be identical with venous blood glucose concentrations. However, skin histamine levels could not be calculated by the no net method, because the data did not meet the theoretic assumptions of this method. In contrast, histamine data fitted theoretically with the flow rate method, and skin histamine concentrations of 18.8 +/- 2.8 nM were found to be significantly greater than plasma histamine concentrations of 4.3 +/- 0.7 nM. Within minutes after intradermal injection of codeine, recovery increased significantly in a dose-dependent fashion. Vasodilation per se did not influence recovery. In conclusion, absolute assessment of skin histamine concentrations can be made by microdialysis by the flow rate method. The validity of such an estimate and the theoretic prerequisites for the calculations are discussed. Quantitative measurement of skin histamine levels during allergic reactions cannot be performed since recovery is altered by plasma extravasation after skin challenge.
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Affiliation(s)
- L J Petersen
- Department of Dermatology, Bispebjerg Hospital, University of Copenhagen, Denmark
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Abstract
BACKGROUND Both the in vitro microbiologic activity of an antibiotic drug and its pharmacokinetic characteristics are important criteria to be considered when predicting clinical efficacy. At present, however, it is not clear which pharmacokinetic parameters are the most useful in determining optimal therapeutic approaches. OBJECTIVES To review the various pharmacokinetic properties of antibiotics, with special reference to the cephalosporins, and to consider the contributions that these make to the definitive prediction of clinical efficacy. DISCUSSION It is important, when attempting to use the pharmacokinetic parameters in conjunction with the minimum inhibitory concentrations for possible pathogens to predict clinical efficacy, to measure the concentration of an antibacterial drug at the site of bacterial proliferation. In most cases bacteria proliferate in the interstitial fluid; therefore it is important to choose an antibiotic that achieves high concentrations in this compartment; the intracellular concentration is less critical. The interstitial fluid concentration is in equilibrium with the free (i.e. non-protein-bound) serum concentration and either of these antibiotic levels is more predictive of clinical efficacy than are intracellular levels.
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Affiliation(s)
- F Scaglione
- Department of Pharmacology, University of Milan, Italy
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33
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Kovar A, Dalla Costa T, Derendorf H. Comparison of plasma and free tissue levels of ceftriaxone in rats by microdialysis. J Pharm Sci 1997; 86:52-6. [PMID: 9002459 DOI: 10.1021/js960244a] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Ceftriaxone has a very high plasma protein binding (up to 98%) that is saturable and decreases with higher concentrations. This high protein binding results in high concentrations in plasma that are frequently related to the anti-infective activity. However, because only the free fraction of the drug is pharmacologically active and most of the infections are located in the tissues, it is more relevant to evaluate unbound concentrations in the interstitial space. Plasma and tissue pharmacokinetics of ceftriaxone in rats after single intravenous administration were investigated at two different concentrations (50 and 100 mg/kg). Both plasma and tissue samples were taken simultaneously from the same animal and analyzed by reversed-phase high-performance liquid chromatography. Free tissue levels in the thigh muscle were measured by microdialysis. The concentration in plasma is much higher than the free concentration in tissue. After determination of nonlinear protein binding by microdialysis and including these parameters in the pharmacokinetic model, it is possible to predict free concentrations in the interstitial space from plasma levels for any given dose.
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Affiliation(s)
- A Kovar
- Department of Pharmaceutics, College of Pharmacy, University of Florida, Gainesville 32610, USA
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Kovar A, Nolting A, Derendorf H. [Microdialysis for the determination of free drugs in tissues]. PHARMAZIE IN UNSERER ZEIT 1997; 26:17-23. [PMID: 9157461 DOI: 10.1002/pauz.19970260108] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- A Kovar
- College of Pharmacy, Department of Pharmaceutics, Health Science Center, Gainesville, Fl 32610-0494, USA
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Müller M, Haag O, Burgdorff T, Georgopoulos A, Weninger W, Jansen B, Stanek G, Pehamberger H, Agneter E, Eichler HG. Characterization of peripheral-compartment kinetics of antibiotics by in vivo microdialysis in humans. Antimicrob Agents Chemother 1996; 40:2703-9. [PMID: 9124826 PMCID: PMC163607 DOI: 10.1128/aac.40.12.2703] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The calculation of pharmacokinetic/pharmacodynamic surrogates from concentrations in serum has been shown to yield important information for the evaluation of antibiotic regimens. Calculations based on concentrations in serum, however, may not necessarily be appropriate for peripheral-compartment infections. The aim of the present study was to apply the microdialysis technique for the study of the peripheral-compartment pharmacokinetics of select antibiotics in humans. Microdialysis probes were inserted into the skeletal muscle and adipose tissue of healthy volunteers and into inflamed and noninflamed dermis of patients with cellulitis. Thereafter, volunteers received either cefodizime (2,000 mg as an intravenous bolus; n = 6), cefpirome (2,000 mg as an intravenous bolus; n = 6), fleroxacin (400 mg orally n = 6), or dirithromycin (250 mg orally; n = 4); the patients received phenoxymethylpenicillin (4.5 x 10(6) U orally; n = 3). Complete concentration-versus-time profiles for serum and tissues could be obtained for all compounds. Major pharmacokinetic parameters (elimination half-life, peak concentration in serum, time to peak concentration, area under the concentration-time curve [AUC], and AUC/MIC ratio) were calculated for tissues. For cefodizime and cefpirome, the AUCtissue/AUCserum ratios were 0.12 to 0.35 and 1.20 to 1.79, respectively. The AUCtissue/AUCserum ratios were 0.34 to 0.38 for fleroxacin and 0.42 to 0.49 for dirithromycin. There was no visible difference in the time course of phenoxymethylpenicillin in inflamed and noninflamed dermis. We demonstrated, by means of microdialysis, that the concept of pharmacokinetic/pharmacodynamic surrogate markers for evaluation of antibiotic regimens originally developed for serum pharmacokinetics can be extended to peripheral-tissue pharmacokinetics. This novel information may be useful for the rational development of dosage schedules and may improve predictions regarding therapeutic outcome.
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Affiliation(s)
- M Müller
- Department of Clinical Pharmacology, University of Vienna, Austria
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Sato H, Kitazawa H, Adachi I, Horikoshi I. Microdialysis assessment of microfibrous collagen containing a P-glycoprotein-mediated transport inhibitor, cyclosporine A, for local delivery of etoposide. Pharm Res 1996; 13:1565-9. [PMID: 8899852 DOI: 10.1023/a:1016096016642] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
PURPOSE This study was designed to assess a local drug delivery system of an anticancer agent, etoposide (VP-16), using microfibrous collagen as a drug carrier. For this objective, the microdialysis method was utilized to investigate the local pharmacokinetics of VP-16. METHODS Microfibrous collagen sheets (CS) containing 20 mg/kg of VP-16 with and without 40 mg/kg of cyclosporine A (CyA) were prepared and applied on the liver surface of rats. VP-16 concentrations in the liver extracellular fluid (ECF) were monitored by a microdialysis method. RESULTS The local application of CS containing VP-16 resulted in a relatively long maintenance of drug concentrations in the liver ECF with very low concentrations in plasma. The inclusion of CyA in the CS resulted in 2-fold and 3-fold increases of the AUC and MRT values of VP-16 in the liver ECF, respectively. The liver ECF-to-plasma AUC ratios of VP-16 were 32-39 and 0.17 with local CS application and iv administration, respectively, indicating a remarkable advantage of the local drug delivery system. A pharmacokinetic interaction experiment suggested that the observed increase of the liver ECF concentrations of VP-16 with CyA resulted from inhibition of the biliary excretion of VP-16 by CyA. CONCLUSIONS We found that the local delivery of the CS containing CyA on the liver surface is advantageous in terms of the extent and duration of liver ECF drug concentrations, when CyA was included in the CS. The effect of CyA was probably derived from the inhibition of P-glycoprotein-mediated biliary excretion of VP-16 by CyA. The usefulness of the microdialysis technique for the assessment of the local drug delivery system was also demonstrated.
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Affiliation(s)
- H Sato
- Department of Hospital Pharmacy, Toyama Medical and Pharmaceutical University, Japan
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Nolting A, Costa TD, Vistelle R, Rand KH, Derendorf H. Determination of free extracellular concentrations of piperacillin by microdialysis. J Pharm Sci 1996; 85:369-72. [PMID: 8901070 DOI: 10.1021/js950304x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The tissue penetration and distribution of antibiotics is of great importance, since most of the infections occur in the tissue. At the infection site, the free, unbound fraction of the antibiotic is responsible for the antiinfective effect. These free extracellular concentrations can be measured by microdialysis. It was the aim of the study to correlate free levels of the beta-lactam antibiotic piperacillin in blood with those in tissue. In vivo microdialysis sampling was used to study the tissue distribution patterns of piperacillin in anesthetized rats after single dose iv administration of the drug. The pharmacokinetics of piperacillin in plasma were consistent with a two-compartment body model. Comparisons between calculated free concentrations in the peripheral compartment and measured free extracellular concentrations revealed excellent agreement. Microdialysis is a suitable method to evaluate unbound drug concentrations in the tissues. In case of piperacillin, predictions of the concentration time profiles of free drug in the peripheral compartment can be made on the basis of plasma data.
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Affiliation(s)
- A Nolting
- Department of Pharmaceutics, University of Florida, Gainesville 32610, USA
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Oravcová J, Böhs B, Lindner W. Drug-protein binding sites. New trends in analytical and experimental methodology. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL APPLICATIONS 1996; 677:1-28. [PMID: 8925081 DOI: 10.1016/0378-4347(95)00425-4] [Citation(s) in RCA: 238] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
In the last few years, continuous progress in instrumental analytical methodology has been achieved with a substantial increase in the number of new, more specific and more flexible methods for ligand-protein assays. In general, the methods used for drug-protein binding studies can be divided into two main groups: separation methods (enabling the calculation of binding parameters, i.e. the number of binding sites and their respective affinity constants) and non-separation methods (describing predominantly qualitative parameters of the ligand-protein complex). This review will be focussed particularly on recent trends in the development of drug-protein binding methods including stereoselective and non-stereoselective aspects using chromatography, capillary electrophoresis and microdialysis as compared to the "conventional approach" using equilibrium dialysis, ultrafiltration or size exclusion chromatography. The advantages and limitations of various methods will be discussed including a focus on "optimal" experimental strategies taking into account in vitro, ex vivo and/or in vivo studies. Furthermore, the importance of some particular aspects concerning the drug binding to proteins (covalent binding of drugs and metabolites, stereoselective interactions and evaluation of binding data) will be outlined in more detail.
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Affiliation(s)
- J Oravcová
- Institute of Pharmaceutical Chemistry, Karl-Franzens-University of Graz, Austria
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Deguchi Y, Inabe K, Tomiyasu K, Nozawa K, Yamada S, Kimura R. Study on brain interstitial fluid distribution and blood-brain barrier transport of baclofen in rats by microdialysis. Pharm Res 1995; 12:1838-44. [PMID: 8786954 DOI: 10.1023/a:1016263032765] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
PURPOSE This study was performed to examine the distribution in the brain interstitial fluid (ISF) and the blood-brain barrier (BBB) transport of baclofen in rats by a microdialysis technique. METHODS Following an i.v. bolus administration and/or the constant i.v. infusion of baclofen to the microdialysis cannula-bearing anesthetized rats, the concentrations of baclofen in the hippocampal ISF, whole brain tissue, cerebrospinal fluid (CSF), and plasma were determined by high-performance liquid chromatography (HPLC). Data were kinetically analyzed to estimate the transport parameters, i.e., the influx clearance (CLin) from plasma to brain and the efflux rate constant (keff) from brain to plasma, and the steady-state volume of distribution in the brain (Vd). RESULTS The concentrations of baclofen in ISF, whole brain tissue, and CSF at the pseudo-steady state were almost 30-fold lower than the plasma unbound concentration, suggesting the restricted distribution of baclofen in the brain. The estimated values of CLin and keff were 0.00157 +/- 0.00076 ml/min/g of brain and 0.0872 +/- 0.0252 min-1, respectively. The efflux clearance (CLout) calculated by multiplying keff by Vd (0.816 +/- 0.559 ml/g of brain) was 0.0712 +/- 0.0529 ml/min/g of brain, and it was significantly 40-fold greater than the CLin value and fully greater than the convective flow in ISF. Furthermore, no significant concentration gradient was observed between ISF and CSF. These results suggest that the CLout value mainly reflects the efflux clearance through the BBB. Additionally, the hippocampal ISF/plasma concentration ratio of baclofen was markedly increased by both systemic administration of probenecid and its direct instillation into ISF. CONCLUSIONS The restricted distribution of baclofen in the brain ISF may be ascribed to the efficient efflux from the brain through the BBB which is regulated possibly by a probenecid-sensitive organic anion transport system.
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Affiliation(s)
- Y Deguchi
- Department of Biopharmacy, School of Pharmaceutical Sciences, University of Shizuoka, Japan
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van Amsterdam C, Boukhabza A, Ofner B, Pacha W, Lemaire M. Measurement of free concentration of SDZ ICM 567 in blood and muscle using microdialysis sampling. Biopharm Drug Dispos 1995; 16:521-7. [PMID: 7579033 DOI: 10.1002/bdd.2510160609] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- C van Amsterdam
- Department of Drug Metabolism and Pharmacokinetics 507/801, Sandoz Pharma Ltd., Basel, Switzerland
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Tetsuya T, Yoshiharu D, Yuko K, Pardridge WM, Akira T. Determination of in vivo steady-state unbound drug concentration in the brain interstitial fluid by microdialysis. Int J Pharm 1992. [DOI: 10.1016/0378-5173(92)90006-n] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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