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Lombardo F, Obach RS, Waters NJ. Plasma Protein Binding and Volume of Distribution: Determination, Prediction and Use in Early Drug Discovery. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/9783527627448.ch9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Bertera FM, Mayer MA, Opezzo JAW, Taira CA, Höcht C. Increased sensitivity to diltiazem hypotensive effect in an experimental model of high-renin hypertension. J Pharm Pharmacol 2010. [DOI: 10.1211/jpp.61.01.0011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Abstract
Objectives
The aim of this work was to evaluate the pharmacokinetic–pharmacodynamic properties of diltiazem in an experimental model of high-renin hypertension, such as the aortic coarctated (ACo) rat, to further characterize the responsiveness of this model to calcium channel blockers.
Methods
A ‘shunt’ microdialysis probe was inserted in a carotid artery of anaesthetized ACo and control sham-operated (SO) rats for simultaneous determination of diltiazem plasma concentrations and their effects on mean arterial pressure and heart rate after the intravenous application of 3 and 6 mg/kg of the drug. Correlation between plasma levels and cardiovascular effects was established by fitting the data to a modified Emax model.
Key findings
Volume of distribution was greater in ACo than in SO rats. Diltiazem plasma clearance (Cl) was significantly greater in ACo rats than in normotensive SO rats after administration of diltiazem (6 mg/kg). Moreover, Cl increased with dose in ACo but not in SO rats. No differences were observed in the maximal bradycardic effect comparing both experimental groups, and sensitivity (S0) to diltiazem chronotropic effect was similar comparing SO and ACo rats. Differences were not found in the maximal response of the hypotensive effect comparing SO and ACo rats, but the S0 to diltiazem hypotensive effect was greater in ACo rats than in SO rats.
Conclusions
ACo induced profound changes in diltiazem pharmacokinetic behaviour. In addition, our results suggested an increased sensitivity to diltiazem blood pressure lowering effect in experimental renovascular hypertension with high-renin levels.
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Affiliation(s)
- Facundo M Bertera
- Cátedra de Farmacología, Universidad de Buenos Aires, Junín 956, (C1113AAD) Buenos Aires, Argentina
| | - Marcos A Mayer
- Cátedra de Farmacología, Universidad de Buenos Aires, Junín 956, (C1113AAD) Buenos Aires, Argentina
- Instituto de Fisiopatología y Bioquímica Clínica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, (C1113AAD) Buenos Aires, Argentina
| | - Javier A W Opezzo
- Cátedra de Farmacología, Universidad de Buenos Aires, Junín 956, (C1113AAD) Buenos Aires, Argentina
- Instituto de Fisiopatología y Bioquímica Clínica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, (C1113AAD) Buenos Aires, Argentina
| | - Carlos A Taira
- Cátedra de Farmacología, Universidad de Buenos Aires, Junín 956, (C1113AAD) Buenos Aires, Argentina
- Instituto de Fisiopatología y Bioquímica Clínica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, (C1113AAD) Buenos Aires, Argentina
| | - Christian Höcht
- Cátedra de Farmacología, Universidad de Buenos Aires, Junín 956, (C1113AAD) Buenos Aires, Argentina
- Instituto de Fisiopatología y Bioquímica Clínica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, (C1113AAD) Buenos Aires, Argentina
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Differential hippocampal pharmacokinetics of phenobarbital and carbamazepine in repetitive seizures induced by 3-mercaptopropionic acid. Neurosci Lett 2009; 453:54-7. [DOI: 10.1016/j.neulet.2009.01.079] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2008] [Revised: 01/26/2009] [Accepted: 01/30/2009] [Indexed: 01/16/2023]
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In Vitro and In Vivo Pharmacodynamic Properties of Metoprolol in Fructose-fed Hypertensive Rats. J Cardiovasc Pharmacol 2008; 51:532-41. [DOI: 10.1097/fjc.0b013e3181730306] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Comparison of different pharmacodynamic models for PK–PD modeling of verapamil in renovascular hypertension. J Pharmacol Toxicol Methods 2008; 57:212-9. [DOI: 10.1016/j.vascn.2008.03.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2008] [Accepted: 03/10/2008] [Indexed: 11/23/2022]
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Bertera FM, Mayer MA, Opezzo JAW, Taira CA, Bramuglia GF, Höcht C. Pharmacokinetic–pharmacodynamic modeling of diltiazem in spontaneously hypertensive rats: A microdialysis study. J Pharmacol Toxicol Methods 2007; 56:290-9. [PMID: 17560132 DOI: 10.1016/j.vascn.2007.04.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2007] [Accepted: 04/16/2007] [Indexed: 11/21/2022]
Abstract
INTRODUCTION The aim of the present work was to study the applicability of a modified E(max) pharmacodynamic model for the pharmacokinetic-pharmacodynamic (PK-PD) modeling of diltiazem in spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto (WKY) rats. METHODS A "shunt" microdialysis probe was inserted in a carotid artery of anaesthetized SHR and WKY rats for simultaneous determination of unbound plasma concentrations of diltiazem and their effects on mean arterial pressure (MAP) and heart rate (HR) after the intravenous application of 1 and 3 mg kg(-1) of the drug. Correlation between diltiazem plasma levels and their cardiovascular effects was established by fitting the data to a conventional and modified E(max) model. RESULTS Volume of distribution and clearance of diltiazem was greater in SHR than in WKY animals. A proportional increase of area under curve with dose increment was observed in WKY animals but not in SHR. A good correlation between plasma unbound concentrations of diltiazem and their hypotensive and chronotropic effects was found in both experimental groups using both PK-PD models. The application of the modified E(max) model for PK-PD modeling of diltiazem allowed a more accurate and precise estimation of PK-PD parameters than the E(max) equation do. Chronotropic effect of 3 mg kg(-1) diltiazem was lower in SHR compared to WKY animals. Initial sensitivity (S(0)) to diltiazem chronotropic effect was greater in SHR with regards to WKY animals after administration of 1 mg kg(-1). S(0) to diltiazem hypotensive effect was greater in SHR with regards to WKY animals after administration of both doses of diltiazem. DISCUSSION Microdialysis sampling is a useful technique for the pharmacokinetic study and pharmacokinetic-pharmacodynamic (PK-PD) modeling of diltiazem. The modified E(max) model allows an accurate estimation of drug sensitivity in conditions when maximal pharmacological response can not be attained. Genetic hypertension induced changes in the pharmacokinetic and PK-PD behavior of diltiazem suggesting that SHR is an interesting animal model for pre-clinical evaluation of calcium channel blockers.
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Affiliation(s)
- Facundo M Bertera
- Department of Pharmacology, Faculty of Pharmacy and Biochemistry, University of Buenos Aires, Junín 956, (C1113AAD) Buenos Aires, Argentina
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Höcht C, Lazarowski A, Gonzalez NN, Auzmendi J, Opezzo JAW, Bramuglia GF, Taira CA, Girardi E. Nimodipine restores the altered hippocampal phenytoin pharmacokinetics in a refractory epileptic model. Neurosci Lett 2007; 413:168-72. [PMID: 17240061 DOI: 10.1016/j.neulet.2006.11.075] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2006] [Revised: 10/16/2006] [Accepted: 11/24/2006] [Indexed: 11/27/2022]
Abstract
The present work was undertaken to examine the central pharmacokinetics of phenytoin (PHT) in an experimental model of epilepsy, induced by administration of 3-mercaptopropionic acid (MP), and possible participation of P-glycoprotein in this model of epilepsy. Repeated seizures were induced in male Wistar rats by injection of 3-MP (45 mg kg(-1), i.p.) during 10 days. Control rats (C) were injected with saline solution. In order to monitor extracellular PHT levels, either a shunt microdialysis probe or a concentric probe was inserted into carotid artery or hippocampus, respectively. All animals were administered with PHT (30 mg kg(-1), i.v.) 30 min after intraperitoneal administration of vehicle (V) or nimodipine (NIMO, 2 mg kg(-1)). No differences were found in PHT plasma levels comparing all experimental groups. In pre-treated rats with V, hippocampal PHT concentrations were lower in MP (maximal concentration, C(max): 2.7+/-0.3 microg ml(-1), p<0.05 versus C rats) than in C animals (C(max): 5.3+/-0.9 microg ml(-1)). Control rats pre-treated with NIMO showed similar results (C(max): 4.5+/-0.8 microg ml(-1)) than those pre-treated with V. NIMO pre-treatment of MP rats showed higher PHT concentrations (C(max): 6.8+/-1.0 microg ml(-1), p<0.05) when compared with V pre-treated MP group. Our results indicate that central pharmacokinetics of PHT is altered in MP epileptic rats. The effect of NIMO on hippocampal concentrations of PHT suggests that P-glycoprotein has a role in reduced central bioavailability of PHT in our epileptic refractory model.
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Affiliation(s)
- Christian Höcht
- Cátedra de Farmacología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, (C1113AAD) Buenos Aires, Argentina.
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Höcht C, Opezzo JAW, Bramuglia GF, Taira CA. Application of microdialysis for pharmacokinetic-pharmacodynamic modelling. Expert Opin Drug Discov 2006; 1:289-301. [DOI: 10.1517/17460441.1.4.289] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Höcht C, DiVerniero C, Opezzo JAW, Taira CA. Applicability of microdialysis as a technique for pharmacokinetic-pharmacodynamic (PK-PD) modeling of antihypertensive beta-blockers. J Pharmacol Toxicol Methods 2006; 52:244-50. [PMID: 16125622 DOI: 10.1016/j.vascn.2005.01.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2004] [Accepted: 01/18/2005] [Indexed: 11/25/2022]
Abstract
INTRODUCTION The aim of the present work was to examine microdialysis as a technique for the study of pharmacokinetic-pharmacodynamic modeling of antihypertensive drugs. For this purpose, we studied the antihypertensive and the chronotropic effect of metoprolol and its plasma concentrations in sham operated (SO) and aortic coarctated (ACo) rats at an early hypertensive stage. METHODS Plasma metoprolol concentrations were obtained by means of a "shunt" vascular microdialysis probe. Changes in mean arterial pressure and heart rate were also measured in the same experiment. RESULTS A rapid decay of metoprolol levels was observed in both experimental groups. For the chronotropic effect, a good association between plasma levels and the chronotropic effect was observed in SO and ACo rats. ACo rats had a greater sensitivity to the chronotropic effect (Emax:-38+/-2%, n=5, p<0.05) than SO animals (Emax:-27+/-1%, n=5). A delay in the blood pressure reduction induced by metoprolol was observed in both experimental groups. A good association was observed between concentrations of metoprolol in the effect compartment and the corresponding hypotensive effect in both experimental groups. The calculated PK-PD parameters were not different between SO and ACo groups. DISCUSSION A good correlation was found between metoprolol concentration and its chronotropic and antihypertensive effects in normotensive and ACo hypertensive rats, allowing the employment of PK-PD models. The microdialysis technique allows simultaneous determination of plasma levels of antihypertensive drugs and their cardiovascular effects, and is therefore a powerful tool for PK-PD modeling.
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Affiliation(s)
- Christian Höcht
- Cátedra de Farmacología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Batalla de Junín 956, C1113AAD Buenos Aires, Argentina.
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Höcht C, Opezzo JAW, Taira CA. Applicability of reverse microdialysis in pharmacological and toxicological studies. J Pharmacol Toxicol Methods 2006; 55:3-15. [PMID: 16567112 DOI: 10.1016/j.vascn.2006.02.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2006] [Accepted: 02/15/2006] [Indexed: 10/24/2022]
Abstract
A recent application of microdialysis is the introduction of a substance into the extracellular space via the microdialysis probe. The inclusion of a higher amount of a drug in the perfusate allows the drug to diffuse through the microdialysis membrane to the tissue. This technique, actually called as reverse microdialysis, not only allows the local administration of a substance but also permits the simultaneous sampling of the extracellular levels of endogenous compounds. Local effects of exogenous compounds have been studied in the central nervous system, hepatic tissue, dermis, heart and corpora luteae of experimental animals by means of reverse microdialysis. In central nervous studies, reverse microdialysis has been extensively used for the study of the effects on neurotransmission at different central nuclei of diverse pharmacological and toxicological agents, such as antidepressants, antipsychotics, antiparkinsonians, hallucinogens, drugs of abuse and experimental drugs. In the clinical setting, reverse microdialysis has been used for the study of local effects of drugs in the adipose tissue, skeletal muscle and dermis. The aim of this review is to describe the principles of the reverse microdialysis, to compare the technique with other available methods and finally to describe the applicability of reverse microdialysis in the study of drugs properties both in basic and clinical research.
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Affiliation(s)
- Christian Höcht
- Cátedra de Farmacología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, (C1113AAD) Buenos Aires, Argentina.
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Gao ZB, Ding PT, Zhang L, Yuan ZT, Shi J, Wei J, Chen DW. Application of microdialysis to study thein vivo release of pingyangmycin fromin situ gels in rabbits. Biomed Chromatogr 2006; 20:1223-8. [PMID: 16799932 DOI: 10.1002/bmc.688] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Microdialysis was used together with HPLC to monitor the local concentration of pingyangmycin hydrochloride (PYM) after embolizing rabbit ear-veins with an injectable sustained release formulation, PYM-Zein/PYM-Zein-sucrose acetate isobutyrate (SAIB), in situ gel. The dialysis probe was perfused at 2 microL/min. The in vivo recovery was 46.6 3.1% (n = 4). The samples were injected directly into HPLC. PYM was detected using UV detector at 291 nm. Separation from other components in the dialysate was performed using a Discovery((R)) RP-Amide C(16) column within 12 min. The response for PYM in the dialysate was linear (r(2) > 0.996) over the range of 2.5-212 microg/mL. The limit of detection and limit of quantitation of PYM in the dialysate were 0.4 and 1.5 microg/mL, respectively. The results demonstrated that the in situ gel of PYM-Zein-SAIB could extend the release of PYM to 4 days. SAIB could significantly cut down the initial burst of PYM from the in situ gels (p < 0.05).
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Affiliation(s)
- Zi-bin Gao
- Department of Pharmaceutics, Shenyang Pharmaceutical University, Wenhua Road 103, Shenyang 110016, People's Republic of China
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Abrahamsson P, Winsö O. An assessment of calibration and performance of the microdialysis system. J Pharm Biomed Anal 2005; 39:730-4. [PMID: 15939565 DOI: 10.1016/j.jpba.2005.04.036] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2004] [Revised: 04/12/2005] [Accepted: 04/12/2005] [Indexed: 11/18/2022]
Abstract
To improve the reliability of microdialysis measurements of tissue concentrations of metabolic substances, this study was designed to test both the performance and the internal validity of the microdialysis methods in the hands of our research group. The stability of the CMA 600 analyser was tested with a known glucose solution in 72 standard microvials and in 48 plastic vials. To evaluate if variation in sampling time makes any difference in sample concentration (recovery), sampling times of 10, 20 and 30 min were compared in vitro with a constant flow rate of 1 microl/min. For testing of sampling times at different flow rates, an in vitro study was performed in which a constant sample volume of 10 microl was obtained. With the no net flux method, the actual concentration of glucose and urea in subcutaneous tissue was measured. The CMA 600 glucose analysis function was accurate and stable with a coefficient of variability (CV) of 0.2-0.55%. There was no difference in recovery for the CMA 60 catheter for glucose when sampling times were varied. Higher flow rates resulted in decreased recovery. Subcutaneous tissue concentrations of glucose and urea were 4.4 mmol/l and 4.1 mmol/l, respectively. To conclude, this work describes an internal validation of our use of the microdialysis system by calibration of vials and catheters. Internal validation is necessary in order to be certain of adequate sampling times, flow rates and sampling volumes. With this in mind, the microdialysis technique is useful and appropriate for in vivo studies on tissue metabolism.
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Affiliation(s)
- Pernilla Abrahamsson
- Department of Surgical and Perioperative Sciences, Anesthesiology and Intensive Care, Umeå University Hospital, Umeå, Sweden.
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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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Höcht C, Opezzo JAW, Taira CA. Hypothalamic Antihypertensive Effect of Irbesartan in Chronic Aortic Coarctated Rats. Pharmacology 2005; 73:146-54. [PMID: 15564789 DOI: 10.1159/000082348] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2004] [Accepted: 09/13/2004] [Indexed: 11/19/2022]
Abstract
The aim of the present work was to study the central and plasma pharmacokinetics of irbesartan (IRB) and its possible hypothalamic antihypertensive effect in sham-operated (SO) and aortic-coarctated (ACo) rats at a chronic hypertensive stage using the microdialysis technique. Anesthetized Wistar rats were used 42 days after ACo or SO. For the study of plasma pharmacokinetics, a vascular shunt probe was inserted into the carotid artery. In a separated experiment, a concentric probe was placed into the anterior hypothalamus for the study of IRB distribution in the central nervous system. Based on the hypothalamic concentrations of IRB reached in ACo rats, the anterior hypothalamus of SO and ACo animals was perfused with a Ringer solution containing approximately 6 microg x ml(-1) of the drug. IRB (10 mg x kg(-1) i.v.) induced a late decrease of heart rate (HR) in ACo animals (DeltaHR: -42 +/- 10 bpm, n = 5, p < 0.05 vs. SO rats) but not in SO rats (DeltaHR: 11 +/- 13 bpm, n = 5). Systemic administration of the drug reduced the mean arterial pressure (MAP) of both experimental groups, but the hypotensive effect was greater in ACo (DeltaMAP: -39.9 +/- 5.0 mm Hg, n = 5, p < 0.05 vs. SO rats) than in SO rats (DeltaMAP: -25.4 +/- 2.1 mm Hg, n = 5). A similar pharmacokinetic profile was observed in both experimental groups. Hypothalamic distribution of IRB was greater in ACo (AUC: 730 +/- 130 ng x ml(-1) h(-1), n = 5, p < 0.05 vs. SO rats) than in SO animals (AUC: 283 +/- 87 ng x ml(-1) h(-1), n = 5). The IRB hypothalamic perfusion induced an antihypertensive effect in ACo (DeltaMAP: -15.1 +/- 1.0 mm Hg, n = 5, p < 0.05 vs. Ringer perfusion) but not in SO rats. In conclusion, the chronic aortic coarctation did not modify the plasma pharmacokinetics of IRB, but it increased the distribution of the drug in the central nervous system. The greater hypotensive effect of IRB observed in ACo animals suggests the involvement of AT1 receptors in the maintenance of the hypertensive stage in chronic ACo rats. The hypotensive effect of IRB in ACo animals could be explained, at least in part, due an action on the anterior hypothalamic angiotensin system.
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Affiliation(s)
- Christian Höcht
- Department of Pharmacology, Faculty of Pharmacy and Biochemistry, University of Buenos Aires, Buenos Aires, Argentina.
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