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Cengiz N, Adibelli Z, Yakupoğlu YK, Türker H. Neurological Complications after Renal Transplantation: A Retrospective Clinical Study. Noro Psikiyatr Ars 2015; 52:331-335. [PMID: 28360735 DOI: 10.5152/npa.2015.9876] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2014] [Accepted: 11/19/2014] [Indexed: 11/22/2022] Open
Abstract
INTRODUCTION The aim of this study was to evaluate the incidence and types of neurological complications (NCs) and associated factors in renal transplantation (RT) patients. METHODS Three hundred and forty-four patients who had RT performed at our institution between January 2005 and July 2014 were retrospectively evaluated. RESULTS File records of the patients revealed 19 who experienced a total of 22 episodes of NCs, of whom three had more than one episode. The mean age of 19 patients included in the study, of whom eight were female, was 37.52±13.08 (range, 18-65) years. NCs were classified into central or peripheral depending on the location of involvement of the central nervous system (CNS). CNS involvement was found in 16 (84.2%) of the 19 patients. Tremor (36.8%) was the most common CNS complication in these patients. Encephalopathy, generalized tonic-clonic seizures, and status epilepticus were observed in two patients (10.5%). Delirium and dementia were observed in one patient (5.2%). Headache was experienced by one patient, and agitated depression was observed in one patient. Six patients (26.3%) had the peripheral nervous system involvement. One patient had the numbness of hands with normal electromyography findings, and four patients had polyneuropathy. In one patient, lumbar plexopathy was observed. Seventeen of the 22 NCs were considered to be caused by immunosuppressive agents. Each incidence of amyloidosis, infection, septic emboli, and hypoglycemia caused a neurological episode. The etiology of one episode was unknown. CONCLUSION Different neurological disorders can be seen after RT, and most of them are caused by immunosuppressive drugs. NCs seen after RT can be treated by decreasing the dose or changing the immunosuppressive drug.
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Affiliation(s)
- Nilgün Cengiz
- Department of Neurology, Ondokuz Mayıs University, Faculty of Medicine, Samsun, Turkey
| | - Zelal Adibelli
- Department of Nephrology, Atatürk State Hospital, Antalya, Turkey
| | | | - Hande Türker
- Department of Neurology, Ondokuz Mayıs University, Faculty of Medicine, Samsun, Turkey
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Clinical Pharmacokinetics of Once-Daily Tacrolimus in Solid-Organ Transplant Patients. Clin Pharmacokinet 2015; 54:993-1025. [DOI: 10.1007/s40262-015-0282-2] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Zununi Vahed S, Ardalan M, Samadi N, Omidi Y. Pharmacogenetics and drug-induced nephrotoxicity in renal transplant recipients. BIOIMPACTS : BI 2015; 5:45-54. [PMID: 25901296 PMCID: PMC4401167 DOI: 10.15171/bi.2015.12] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2014] [Revised: 06/07/2014] [Accepted: 06/09/2014] [Indexed: 12/11/2022]
Abstract
INTRODUCTION The advent of calcineurin inhibitors (CNIs), as the leading immunosuppressive agents, not only has revolutionized the transplant medicine but also made it a better therapeutic intervention that guarantees the graft outcome and improves the survival rate of patients. However, genetic polymorphism(s) in the CNIs metabolic substrates genes (CYP3A4, CYP3A5) and their transporter such as P-glycoprotein (P-gp) can influence the CNIs metabolism and elicit some possible systemic and intra-renal exposures to drugs and/or metabolites with differential risk of nephrotoxicity, jeopardizing the transplantation. METHODS In the current study, we review the recent literatures to evaluate the effects of genetic polymorphisms of the genes involved in development of chronic calcineurin nephrotoxicity and progression of chronic allograft dysfunction (CAD) providing an extensive overview on their clinical impacts. RESULTS Identifying the inherited genetic basis for the inter-individual differences in terms of drug responses and determining the risk of calcineurin-mediated nephrotoxicity and CAD allow optimized personalized administration of these agents whith minimal adverse effects. CONCLUSION Pharmacogenetics characteristics of CYP isoforms (CYP3A) and efflux transporters (P-gp and MRP), involved in metabolism and extracellular transportation of the immunosuppressive CNIs, can be of pivotal information in the pharmacotherapy of the renal-transplant recipients. Such information can be used for the successes clinical interventions to attain an improved drug administration strategy with reduced rates of rejection and toxicity.
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Affiliation(s)
- Sepideh Zununi Vahed
- Research Center for Pharmaceutical Nanotechnology, School of Advanced Biomedical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
- Chronic Kidney Disease Research Center, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
- Research Center for Pharmaceutical Nanotechnology, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Mohammadreza Ardalan
- Research Center for Pharmaceutical Nanotechnology, School of Advanced Biomedical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
- Chronic Kidney Disease Research Center, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Nasser Samadi
- Research Center for Pharmaceutical Nanotechnology, School of Advanced Biomedical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Yadollah Omidi
- Research Center for Pharmaceutical Nanotechnology, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran
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Li Y, Hu X, Cai B, Chen J, Bai Y, Tang J, Liao Y, Wang L. Meta-analysis of the effect of MDR1 C3435 polymorphism on tacrolimus pharmacokinetics in renal transplant recipients. Transpl Immunol 2012; 27:12-8. [PMID: 22504573 DOI: 10.1016/j.trim.2012.03.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2011] [Revised: 03/26/2012] [Accepted: 03/27/2012] [Indexed: 02/05/2023]
Abstract
BACKGROUND The published data revealed conflicting results of the polymorphism of MDR1 exon 26 SNP C3435T on the pharmacokinetics of tacrolimus in different post transplant times; thus, the aim was to perform a meta-analysis of different post transplant times to investigate the influence of SNP C3435T on the tacrolimus pharmacokinetics. METHODS A literature search was conducted to locate the relevant papers by using the PUBMED and EMBASE electronic source until 2011. The pharmacokinetic parameters, including dose administration, concentration and concentration to dose ratio were extracted and a meta-analysis was performed by using STATA10.0. RESULTS A total of 13 papers concerning 1327 individuals were included in the meta-analysis. The overall results showed SNP C3435T could influence the pharmacokinetic parameters in different post transplant times, the subjects with CC genotype had lower concentration dose ratio and need higher tacrolimus dose than the CT and TT genotype. CONCLUSIONS Our meta-analysis of available studies has demonstrated a definite correlation between the SNP C3435T in MDR1 gene and pharmacokinetics of tacrolimus. However, additional studies with large sample size and better study designs are warranted to verify our finding.
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Affiliation(s)
- Yi Li
- Department of Clinical Immunological Laboratory, West China Hospital, Sichuan University, Chengdu, People's Republic of China
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Laberge AM, Burke W. Clinical and public health implications of emerging genetic technologies. Semin Nephrol 2010; 30:185-94. [PMID: 20347647 DOI: 10.1016/j.semnephrol.2010.01.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The clinical utility of many emerging genetic technologies has yet to be established. For many new genetic tests, no practice guidelines are available to help clinicians decide when and how to use them in practice. The clinical and public health implications of new genetic technologies are easiest to evaluate when these tests are compared with other genetic tests, including those already well established in clinical practice. Genetic tests can be divided into different categories based on their intent as follows: (1) to establish a diagnosis (genetic diagnostic tests), (2) to classify disease processes to assist management (gene expression profiling), (3) to predict drug response or side effects (pharmacogenomic tests), and (4) to predict susceptibility to disease (genetic susceptibility testing). As new genetic tests emerge, their translation into practice will depend on their performance based on laboratory standards, but also on their ability to enhance prevention or assist clinicians in diagnosing and treating patients. This article reviews the clinical and public health implications of different types of genetic tests, the evaluation of genetic tests from a public health perspective, and the need for partnership to achieve the potential for benefit of new genetic technologies.
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Abstract
Tacrolimus is an immunosuppressive medication in the class of calcineurin inhibitors that acts by inhibiting T-cell and interleukin-2 activity, and is commonly used after allogeneic organ transplant. We present a patient who used tacrolimus after cadaveric kidney transplant and experienced blurry vision. Ocular examination and patient's course subsequently revealed aqueous tear deficiency as a dose-dependent adverse effect of oral tacrolimus.
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Abstract
Neurologic complications affect posttransplant recovery of more than 20% of transplant recipients. Etiology is usually related to surgical procedure of transplantation, primary disorders causing failure of transplanted organ, opportunistic infections, and neurotoxicity of immunosuppressive medications. Risk of opportunistic infections and immunosuppressant neurotoxicity is greatest within the first six months, but it persists along with long-term maintenance immunosuppression required to prevent graft rejection. Neurotoxicity may require alteration of immunosuppressive regimen, and prompt therapy of opportunistic infections improves outcomes.
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Affiliation(s)
- Sasa A Zivković
- Neurology Service, VA Pittsburgh Healthcare System, University Drive C, Pittsburgh, PA 15240, USA.
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Fangmann J, Arns W, Marti HP, Hauss J, Ketteler M, Beckurts T, Boesmueller C, Pohanka E, Martin PY, Gerhardt M, Farese S, Neumayer HH, Floege J, Gurr C, Budde K. Impact of daclizumab, low-dose cyclosporine, mycophenolate mofetil and steroids on renal function after kidney transplantation. Nephrol Dial Transplant 2009; 25:283-92. [PMID: 19773417 DOI: 10.1093/ndt/gfp468] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Early and long-term use of cyclosporine A (CsA) leads to increased risks of renal toxicity. We hypothesized that administration of daclizumab in combination with mycophenolate mofetil (MMF) allows a relevant reduction in the dose of CsA. METHODS We carried out a 3-year, prospective, randomized, controlled clinical multi-centre trial in 156 patients. The patients were randomized to standard treatment (CsA, MMF, steroids) or to high-dose daclizumab (first dose: 2 mg/kg), in combination with low-dose CsA, MMF and steroids. We maintained the mean CsA levels of daclizumab patients at 57% of standard patients (132 versus 216 ng/ml) on Day 7 post-transplant, and 84% by 6 months. RESULTS Primary outcome, creatinine clearance (with imputation of informative dropouts) at 12 months, was significantly better in daclizumab-treated (34 +/- 17) than standard patients (29 +/- 17; P = 0.028, two sided). Only 5 cases of BPAR were recorded in the daclizumab compared to 22 in the standard group (P = 0.0016). Daclizumab patients had 91% event-free survival after 1 year compared to 66% in standard patients (P = 0.00017). CONCLUSION We demonstrate here that high-dose daclizumab in combination with lower CsA levels in adult renal transplant recipients is as or more effective than standard regimen (CsA, MMF, steroids) and may result in better outcomes at 12 months post-transplant with no increase in adverse reactions.
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Affiliation(s)
- Josef Fangmann
- Klinik fuer Visceral, Transplantations, Thorax und Gefaesschirurgie, Universitaetsklinikum Leipzig, Liebigstr. 20, 04103 Leipzig, Germany.
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Joy MS, La M, Bo Xiao. Individualizing Therapy in Patients With Chronic Kidney Disease. J Pharm Pract 2008. [DOI: 10.1177/0897190008315907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Patients with chronic kidney diseases have multiple clinical abnormalities that may affect disposition of drugs, including alterations in glomerular filtration rate, excretion of plasma proteins, reductions in serum albumin, and reductions in drug metabolizing enzyme activity. Inflammation may also influence the previous factors. Concomitant drug therapies can lead to drug— drug interactions that may affect the pharmacokinetics of administered drugs. Pharmacogenomics has begun to be evaluated for effects of genotype and haplotype of drug metabolizing enzymes and transporters on drug disposition. Because of the multiple potential etiologies for alterations in drug disposition in patients with chronic kidney diseases, they require appropriate evaluation for implementation of individualized strategies in therapies to enhance efficacy and reduce toxicities. This review will highlight the disease- and patient-specific variables that are targets for patient-centered approaches to therapeutic interventions. The field of pharmacogenomics will be reviewed with reference to common therapies for transplantation and glomerular diseases.
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Affiliation(s)
- Melanie S. Joy
- School of Medicine, Division of Nephrology and Hypertension, UNC Kidney Center, University of North Carolina, School of Pharmacy, Divisions of Pharmacotherapy and Experimental Therapeutics and Molecular Pharmaceutics, University of North Carolina, Chapel Hill, North Carolina,
| | - Mary La
- School of Medicine, Division of Nephrology and Hypertension, UNC Kidney Center, University of North Carolina
| | - Bo Xiao
- School of Medicine, Division of Nephrology and Hypertension, UNC Kidney Center, University of North Carolina
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Luo Y, Zhang A, Huang H, Zheng S. Haemolytic Uraemic Syndrome after Living-donor Liver Transplantation: Is Small-for-size Graft a Potential Risk Factor? J Int Med Res 2008; 36:599-604. [PMID: 18534145 DOI: 10.1177/147323000803600328] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Haemolytic uraemic syndrome (HUS) is a rare complication of solid organ transplantation. Immunosuppressive drugs, including cyclosporin A and tacrolimus, have frequently been incriminated. Here we report a case of tacrolimus-induced HUS in a woman with small-for-size syndrome after living-donor liver transplantation. Hypertension, microangiopathic anaemia and end-stage renal failure occurred in the immediate post-transplant period; all other risk factors that might be implicated in the development of HUS were investigated and excluded if no evidence was found. A possible association between small-for-size syndrome, which frequently results in a high blood concentration of tacrolimus post-operatively, and the occurrence of HUS is discussed.
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Affiliation(s)
- Y Luo
- Department of Haematology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - A Zhang
- Department of Hepatobiliary Surgery, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - H Huang
- Department of Haematology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - S Zheng
- Department of Hepatobiliary Surgery, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China
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Abstract
Chronic liver disease is a major source of morbidity and mortality in the United States today. There is little information on the interethnic variation in the clinical presentation, therapeutic responses and prognosis of individuals with liver disease. This review will discuss the ethnic variations and implications of the most common liver diseases.
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Ng FL, Holt DW, MacPhee IAM. Pharmacogenetics as a tool for optimising drug therapy in solid-organ transplantation. Expert Opin Pharmacother 2007; 8:2045-58. [PMID: 17714059 DOI: 10.1517/14656566.8.13.2045] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Existing immunosuppressive therapies used for solid-organ transplantation have narrow therapeutic indices, whereby underdosing is associated with acute immunological rejection of the transplanted organ and overdosing is associated with infections and malignancy, as well as organ-specific toxicities. There is significant inter-individual variation in the pharmacokinetics and pharmacodynamics of these drugs, an issue that has been addressed, in part, by therapeutic drug monitoring. Genetic polymorphisms in drug metabolising enzymes, drug efflux pumps and drug targets which may underly this heterogeneity have been identified and may provide a tool to guide prescribing. There are a number of associations between genotype and pharmacology, but as of now, only thiopurine-S-methyltransferase and cytochrome P450 3A5 have a sufficiently large influence to have potential in guiding therapy. Recent studies have also identified that donor genotype may play a significant role in immunosuppressive drug pharmacokinetics and pharmacodynamics.
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Affiliation(s)
- Fu Liang Ng
- Cellular and Molecular Medicine: Renal Medicine and Cardiac and Vascular Sciences Analytical Unit, St. George's, University of London, Cranmer Terrace, London, UK
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Abstract
Recent advancements in immunobiology have introduced several new diagnostic tools for monitoring kidney transplant recipients. These have been added to more established tests that, although imperfect, remain important benchmarks of diagnostic utility. Both new and old tests can be characterized with regard to their practicality, and as to whether they detect aberrant function or define the cause of dysfunction. Unfortunately, no current test is both practical and specific to a particular disease entity. Accordingly, the diagnosis of graft dysfunction remains dependent on the proper use and interpretation of many studies. This article reviews the current assays that have been evaluated in the clinic for the diagnosis of renal allograft-related diseases. These are limited to assays based on routinely obtainable samples such as blood, biopsy tissue, and urine. Newer studies are presented, along with more mundane assays, to highlight the practical use of studies regardless of their degree of mechanistic sophistication.
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Affiliation(s)
- Raffaele Girlanda
- Transplantation Branch, National Institutes of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Department of Health and Human Services, Bethesda, MD 20892, USA
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Ebinger M, Uhr M. ABC drug transporter at the blood-brain barrier: effects on drug metabolism and drug response. Eur Arch Psychiatry Clin Neurosci 2006; 256:294-8. [PMID: 16783492 DOI: 10.1007/s00406-006-0664-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
At the blood-brain barrier (BBB) many cellular and dynamic mechanisms influence the cerebral drug metabolism and the drug response. In this review, we focus mainly on the role P-glycoprotein (P-gp) plays at the BBB. This protein is a 170-kDa ATP-dependent drug transport protein, located in the apical membrane of endothelial cells. Utilizing ATP hydrolysis as an energy source, it exports molecules which attempt to pass through the cell membrane from the outside to the inside, protecting cells from toxins and a wide range of substances. We briefly summarize some of the currently available in vivo and in vitro methods to investigate P-gp and its substrates. Hitherto, no chemical characteristic has been discovered that clearly distinguishes substrates from non-substrates of P-gp. We discuss some examples of substrates stressing the diversity of drugs and endogenous substances that relate to P-gp either as a substrate, an inhibitor, an inducer or as a combination of the above. Finally, we discuss genetic polymorphisms of the genes encoding for P-gp and their effects on drug response.
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Affiliation(s)
- Martin Ebinger
- Max Planck Institute of Psychiatry, Kraepelinstrasse 2-10, 80804 Munich, Germany
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Dey S. Single nucleotide polymorphisms in human P-glycoprotein: its impact on drug delivery and disposition. Expert Opin Drug Deliv 2006; 3:23-35. [PMID: 16370938 DOI: 10.1517/17425247.3.1.23] [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] [Indexed: 01/07/2023]
Abstract
Drug efflux pumps belong to a large family of ATP-binding cassette transporter proteins. These pumps bind their substrate and export it through the membrane using energy derived from ATP hydrolysis. P-glycoprotein, the main efflux pump in this family, is expressed not only in tumour cells but also in normal tissues with excretory function (liver, kidney and the intestine). It has a broad specificity of substrates and plays an important role in drug delivery and disposition. Recently, genetic screening of P-glycoprotein has yielded multiple single nucleotide polymorphisms, which seem to alter transporter function and expression. This review discusses the various polymorphisms of this gene and its impact on drug disposition and diseases.
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Affiliation(s)
- Surajit Dey
- College of Pharmacy, University of Southern Nevada, 11 Sunset Way, Henderson, NV 89014, USA.
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Yu S, Wu L, Jin J, Yan S, Jiang G, Xie H, Zheng S. Influence of CYP3A5 gene polymorphisms of donor rather than recipient to tacrolimus individual dose requirement in liver transplantation. Transplantation 2006; 81:46-51. [PMID: 16421475 DOI: 10.1097/01.tp.0000188118.34633.bf] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
BACKGROUND Tacrolimus is a widely used immunosuppressant in organ transplantation, but it is characterized by a narrow therapeutic index and high interindividual variations of its pharmacokinetics. Tacrolimus is a substrate for CYP3A. It has been conjectured that CYP3A5 polymorphism is associated with tacrolimus pharmacokinetic variations. The objective of this study was to evaluate the contribution of polymorphisms of the donor and recipient CYP3A5 gene on tacrolimus disposition in liver transplantation. METHODS Fifty-three liver transplant recipients treated with tacrolimus were enrolled in this study. Tacrolimus dosage and blood trough concentration were investigated at 1 week, 2 weeks, and 1 month after transplantation. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis was applied to determine the genotype of CYP3A5 gene. RESULTS The concentration/dose (C/D) ratios in patients with *1/*1(*1/*3) genotype donor were significantly lower than in patients with *3/*3 genotype donor at 2 weeks (P = 0.036) and 1 month (P = 0.021), but not at 1 week posttransplantation. Combination analysis showed that such significance still existed between CYP3A5 expressor group and nonexpressor group for both donor and recipient genotype. Also differences of C/D ratio between CYP3A5 expressor and nonexpressor donors in nonexpressor recipients were larger than those between recipients in nonexpressor donors. CONCLUSION The large interindividual variation of tacrolimus dose requirement is influenced by the metabolic activity of CYP3A5. Polymorphisms of the donor CYP3A5 gene seem to contribute more to such variation than the recipient. A larger population and further studies are needed to explore the exact mechanisms for tacrolimus pharmacokinetics.
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Affiliation(s)
- Songfeng Yu
- Key Lab of Combined Multi-organ Transplantation, Ministry of Public Health, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, PR China
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Abstract
New immunosuppressive strategies that can prevent both acute and chronic rejection are being investigated to achieve graft tolerance and to minimize side effects and toxicity that may lead to graft loss. Drug pharmacokinetics and pharmacodynamics, as well as pharmacogenetics, all play a role in customizing treatment to the individual patient. To improve patient compliance, new drug formulations are on trial, such as the modified- release oral form of tacrolimus MR4 for once daily administration, which seems to be equivalent to bid administration in terms of steady-state exposure. Monoclonal/polyclonal antibodies are increasingly used in the induction phase in protocols where steroids are discontinued early. However, discontinuing steroids carries a high risk of acute rejection or organ failure in some subgroups of patients. The supposed benefit of steroid discontinuation may not be enjoyed by all patients. Minimizing anticalcineurin agents may prove to be similarly or even more advantageous. The use of new drugs and new combinations has greatly improved short-term transplant outcomes. The new goal is, therefore, to improve long-term results and particularly to prevent chronic rejection, thus increasing patient and organ survival.
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Affiliation(s)
- M B Regazzi
- Department of Pharmacology, IRCCS Policlinico S. Matteo, Pavia, Italy.
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18
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Szekeres T, Haushofer A. Clinical pharmacogenetics of immunosuppressive drugs in organ transplantation. Pharmacogenomics 2005; 6:163-8. [PMID: 15882134 DOI: 10.1517/14622416.6.2.163] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Organ transplantation has become an important additional option for patients with organ failure. Immunosuppressive drugs showing a very narrow therapeutic window have to be administered. Different transporters and metabolic pathways are responsible for absorption and metabolism of these drugs; for instance, the P-glycoprotein (P-gp) pump regulates the absorption of a drug, and its metabolism is catalyzed by cytochrome P450s (CYPs). As the phenotypes of P-gp or the CYPs are predetermined by their genotypes, genetic testing prior to drug therapy may help to predict the drug doses required. This review describes polymorphisms of the genes coding for P-gp and CYPs, and focuses on the compounds cyclosporin and tacrolimus. It is hoped that this information might help to judge the value of pharmacogenetic testing prior to immunosuppressive therapy in solid organ transplantation.
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Affiliation(s)
- Thomas Szekeres
- Medical University of Vienna, Clinical Institute for Medical and Chemical Laboratory Diagnostics 5H, General Hospital of Vienna, Waehringer Guertel 18-20, A-1090 Vienna, Austria.
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Abstract
A basic tenet of clinical pharmacology is that the pharmacologic activity of an exogenously administered agent is related to the free drug concentration available at its receptor or ligand-binding site. The discipline of pharmacokinetics can be defined as the study of the processes that lead to the availability of an agent to its site of action. In this review we will discuss basic principles of pharmacokinetics that govern the absorption, distribution, metabolism, elimination and binding of immunosuppressive drugs commonly utilized in whole organ transplantation. In a discipline such as organ transplantation, where the agents utilized carry significant toxicity and where failure of efficacy can have dire consequences, knowledge of the pharmacokinetics of the agents utilized has become a basic skill for all transplant professionals. In this review we describe some of the underlying principles that govern the disposition of the agents commonly utilized in solid organ transplantation. In addition, we hope this review will help in understanding some of the basic drug interactions encountered in transplant practice.
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Affiliation(s)
- Titte R Srinivas
- Department of Medicine, University of Florida, Gainesville, Florida, USA
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20
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Morris RG. Immunosuppressant Drug Monitoring: Is the Laboratory Meeting Clinical Expectations? Ann Pharmacother 2005; 39:119-27. [PMID: 15590877 DOI: 10.1345/aph.1e287] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
OBJECTIVE: To review the literature relating to immunosuppressant drug measurement as performed in therapeutic drug monitoring laboratories associated with transplantation centers and consider whether the assay methods widely used for patient dosage management achieve acceptable quality criteria in the context of other sources of variability with these drugs. DATA SOURCES: Articles used were accessed primarily through MEDLINE, as well as references cited in related publications. Searches were restricted to organ transplantation in humans. STUDY SELECTION AND DATA EXTRACTION: Emphasis was placed on the literature relating to the quality of immunosuppressant drug assays, their limitations, and evidence of clinical benefit in dosage individualization. DATA SYNTHESIS: There is a dilemma evident between the quality of the analytical services offered by some diagnostic immunoassay manufacturers and the ability of a significant number of clinical laboratories globally to select only appropriate assay methods. CONCLUSIONS: In many cases, clinical laboratories fail to meet the reasonable clinical expectations required for interpretation of immunosuppressant drug assay results as an adjunct to optimal dosage individualization and patient care.
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Affiliation(s)
- Raymond G Morris
- Clinical Pharmacology Laboratory, The Queen Elizabeth Hospital, Woodville SA, Australia
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21
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Affiliation(s)
- Philip F Halloran
- Division of Nephrology and Transplantation Immunology, University of Alberta, Edmonton, Canada.
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22
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Staatz CE, Tett SE. Clinical pharmacokinetics and pharmacodynamics of tacrolimus in solid organ transplantation. Clin Pharmacokinet 2004; 43:623-53. [PMID: 15244495 DOI: 10.2165/00003088-200443100-00001] [Citation(s) in RCA: 629] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The aim of this review is to analyse critically the recent literature on the clinical pharmacokinetics and pharmacodynamics of tacrolimus in solid organ transplant recipients. Dosage and target concentration recommendations for tacrolimus vary from centre to centre, and large pharmacokinetic variability makes it difficult to predict what concentration will be achieved with a particular dose or dosage change. Therapeutic ranges have not been based on statistical approaches. The majority of pharmacokinetic studies have involved intense blood sampling in small homogeneous groups in the immediate post-transplant period. Most have used nonspecific immunoassays and provide little information on pharmacokinetic variability. Demographic investigations seeking correlations between pharmacokinetic parameters and patient factors have generally looked at one covariate at a time and have involved small patient numbers. Factors reported to influence the pharmacokinetics of tacrolimus include the patient group studied, hepatic dysfunction, hepatitis C status, time after transplantation, patient age, donor liver characteristics, recipient race, haematocrit and albumin concentrations, diurnal rhythm, food administration, corticosteroid dosage, diarrhoea and cytochrome P450 (CYP) isoenzyme and P-glycoprotein expression. Population analyses are adding to our understanding of the pharmacokinetics of tacrolimus, but such investigations are still in their infancy. A significant proportion of model variability remains unexplained. Population modelling and Bayesian forecasting may be improved if CYP isoenzymes and/or P-glycoprotein expression could be considered as covariates. Reports have been conflicting as to whether low tacrolimus trough concentrations are related to rejection. Several studies have demonstrated a correlation between high trough concentrations and toxicity, particularly nephrotoxicity. The best predictor of pharmacological effect may be drug concentrations in the transplanted organ itself. Researchers have started to question current reliance on trough measurement during therapeutic drug monitoring, with instances of toxicity and rejection occurring when trough concentrations are within 'acceptable' ranges. The correlation between blood concentration and drug exposure can be improved by use of non-trough timepoints. However, controversy exists as to whether this will provide any great benefit, given the added complexity in monitoring. Investigators are now attempting to quantify the pharmacological effects of tacrolimus on immune cells through assays that measure in vivo calcineurin inhibition and markers of immunosuppression such as cytokine concentration. To date, no studies have correlated pharmacodynamic marker assay results with immunosuppressive efficacy, as determined by allograft outcome, or investigated the relationship between calcineurin inhibition and drug adverse effects. Little is known about the magnitude of the pharmacodynamic variability of tacrolimus.
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Affiliation(s)
- Christine E Staatz
- School of Pharmacy, The University of Queensland, Brisbane, Queensland, Australia
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MacPhee IAM, Fredericks S, Tai T, Syrris P, Carter ND, Johnston A, Goldberg L, Holt DW. The influence of pharmacogenetics on the time to achieve target tacrolimus concentrations after kidney transplantation. Am J Transplant 2004; 4:914-9. [PMID: 15147425 DOI: 10.1111/j.1600-6143.2004.00435.x] [Citation(s) in RCA: 200] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Previously, we reported that, at 3 months after renal transplantation, individuals with CYP3AP1 genotype CYP3AP1*1 (linked to CYP3A5*1 and strongly associated with expression of CYP3A5) required twofold higher doses of tacrolimus to achieve target blood concentrations than individuals with the genotype CYP3AP1*3/*3 (CYP3A5 nonexpressors). This study assesses the relationship between concentration-controlled dosing during the early period after transplantation, the time to achieve target concentrations and genotype in 178 renal transplant recipients (CYP3AP1*1/*3 or *1/*1: n = 53, CYP3AP1*3/*3: n = 125). Patients with CYP3AP1*1/*3 or *1/*1 had lower mean tacrolimus concentrations during the first week (Median 13.5 vs. 18.5 microg/L, p < 0.0001) with significant delay in achieving target concentrations (15-20 microg/L during week 1, then 10-15 microg/L). More CYP3AP1*3/*3 patients had tacrolimus concentrations above target during the first week (73.6% vs. 35.8%, p = 0.003). There was no difference in the rate of biopsy-confirmed acute rejection, but rejection occurred earlier in the CYP3AP1*1/*3 or *1/*1 group (median 7 d vs. 13 d, p = 0.005). In conclusion, an initial dosing regimen for tacrolimus based on knowledge of the CYP3AP1 genotype and subsequently guided by concentration measurements has the potential to increase the proportion of patients achieving target blood concentrations early after transplantation.
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Affiliation(s)
- Iain A M MacPhee
- Cellular & Molecular Medicine-Renal Medicine, St. George's Hospital Medical School, London, UK.
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Xie HG, Wood AJJ, Kim RB, Stein CM, Wilkinson GR. Genetic variability in CYP3A5 and its possible consequences. Pharmacogenomics 2004; 5:243-72. [PMID: 15102541 DOI: 10.1517/phgs.5.3.243.29833] [Citation(s) in RCA: 208] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The cytochrome P450 3A (CYP3A) subfamily members are the most abundant and important drug-metabolizing enzymes in humans, and wide interindividual variability in CYP3A expression and function is present. CYP3A4 alone cannot fully explain the observed constitutive variability because its genetic variants are relatively uncommon and have limited functional significance, whereas CYP3A5 expression in humans is highly variable and may be contributory. However, it is difficult to delineate the relative contribution of CYP3A4 and CYP3A5, and to differentiate their effects on drug metabolism as their protein structure, function and substrates are so similar. By contrast, molecular biology methods provide the ability to identify CYP3A4 and CYP3A5 genotypes with certainty. This review collates currently available data on CYP3A5 polymorphisms, provides information on the population frequency of each genetic variant in major ethnic groups, and describes in vitro and in vivo studies that have attempted to identify genotype-phenotype associations.
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Affiliation(s)
- Hong-Guang Xie
- Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
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