Racial and ethnic differences in response to medicines: towards individualized pharmaceutical treatment.
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It is now well documented that substantial disparities exist in the quality and quantity of medical care received by minority Americans, especially those of African, Asian and Hispanic heritage. In addition, the special needs and responses to pharmaceutical treatment of these groups have been undervalued or ignored. This article reviews the genetic factors that underlie varying responses to medicines observed among different ethnic and racial groups. Pharmacogenetic research in the past few decades has uncovered significant differences among racial and ethnic groups in the metabolism, clinical effectiveness, and side-effect profiles of many clinically important drugs. These differences must be taken into account in the design of cost management policies such as formulary implementation, therapeutic substitution and step-care protocols. These programs should be broad and flexible enough to enable rational choices and individualized treatment for all patients, regardless of race or ethnic origin. (+info)
Pharmacogenetics of acenocoumarol: cytochrome P450 CYP2C9 polymorphisms influence dose requirements and stability of anticoagulation.
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BACKGROUND AND OBJECTIVES: Cytochrome P4502C9 (CYP2C9) is the main enzyme implicated in coumarinic metabolism. Variant alleles, CYP2C9*2 and CYP2C9*3, have been related to decreased enzymatic activity, but their clinical relevance in acenocoumarol metabolism has not been established. We investigated CYP2C9 polymorphisms in relation to acenocoumarol dose requirement, stability of anticoagulation and bleeding. DESIGN AND METHODS: CYP2C9 genotyping was performed in 325 acenocoumarol-treated patients (INR target between 2.0 and 3.0) and in an additional group of 84 patients with repeated bleeding. RESULTS: Patients with the wild-type CYP2C9*1/*1 genotype (n=169) required a higher maintenance dose of acenocoumarol (17.1 8.7 mg/week) than did patients with the CYP2C9*2 (14.6 6.4 mg/week, p<0.05, N=97) or the CYP2C9*3 allele (11.2 6.2 mg/week, p<0.001, n=59). Out of 170 patients requiring a low-dose of acenocoumarol (70 years (OR=3.73, 95%CI=2.29-6.08, p<0.001), and the CYP2C9*3 allele (OR=4.75, 95%CI=2.36-9.55, p <0.001). Carriers of CYP2C9*3 spent less time within the therapeutic range (64.7 23.1%) than did patients with the CYP2C9*1/*1 genotype (75.1 22.0%, p<0.01), and more frequently had an INR >4.5 at the initiation of treatment (43.9% vs.11.6%, p<0.001), but did not show repeated bleeding more frequently (19.0% vs.15.5%, p=NS). INTERPRETATION AND CONCLUSIONS: CYP2C9*3 is related to lower acenocoumarol dose requirements, a higher frequency of over-anticoagulation at the initiation of therapy and an unstable anticoagulant response. (+info)
Pharmacogenetics in rheumatology: the prospects and limitations of an emerging field.
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OBJECTIVES: To review the fundamental concepts of pharmacogenetics and analyse how the broad principles of this rapidly emerging field may influence the treatment of rheumatic disease in future. METHODS: The names of common rheumatic drugs and the terms 'pharmacogenetics', 'pharmacogenomics' and 'genetic polymorphism' were used as keywords to search the Medline and Current Contents databases. General review articles on pharmacogenetics were also examined. RESULTS: Pharmacogenetics is the study of how genetic differences influence the variability in drug toxicity and efficacy. Although the principles of pharmacogenetics have been known for several decades, recent technological advances have hastened the possibility of direct clinical applications. Most studies so far have been phenotypic analyses, but genotyping is now readily available for many polymorphisms. There are several examples pertinent to rheumatology that illustrate the important principles and foretell the usefulness of pharmacogenetics in individualizing therapy. However, further studies are needed. CONCLUSIONS: Because traditional pharmacotherapy in rheumatology has been empirical and because of the slow acting nature of many anti-rheumatic medications, the risk of significant side-effects and the increasing armamentarium of drugs available, pharmacogenetics is particularly relevant to rheumatology. There are many scientific and non-scientific concerns that should be addressed in future studies. (+info)
Role of genetic and expression profiling in pharmacogenomics: the changing face of patient management.
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As the determination of gene sequences and their function gains speed at the dawn of the third millennium, biomedical research efforts are oriented towards definition of the genetic and molecular expression patterns that may drive different disease. A major part of these efforts is addressed to the definition of inter-individual variations that are expected to become integral for treatment planning, in terms of efficacy and adverse effects of drugs. It is this thrust on genome-based 'rational therapeutics' that is hoped to progressively lead to the era of 'personalized medicine'. This approach uses the technological expertise from genomics and functional genomics to define, predict and monitor the nature of the response of an individual to drugs, and to rationally design newer drugs. In the present review we will conduct our readers through an understanding of the fundamentals of pharmacogenomics and of the technologies currently available that are advancing this relatively new science. Conversely, there are issues raised that concern how medical practice is preparing itself to implement new alternatives for therapeutical interventions and finally, how to respect patient confidentiality and rights. (+info)
Sulfation through the looking glass--recent advances in sulfotransferase research for the curious.
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Members of the cytosolic sulfotransferase (SULT) superfamily catalyse the sulfation of a multitude of xenobiotics, hormones and neurotransmitters. Humans have at least 10 functional SULT genes, and a number of recent advances reviewed here have furthered our understanding of SULT function. Analysis of expression patterns has shown that sulfotransferases are highly expressed in the fetus, and SULTs may in fact be a major detoxification enzyme system in the developing human. The X-ray crystal structures of three SULTs have been solved and combined with mutagenesis experiments and molecular modelling, they have provided the first clues as to the factors that govern the unique substrate specificities of some of these enzymes. In the future these and other studies will facilitate prediction of the fate of chemicals metabolised by sulfation. Variation in sulfation capacity may be important in determining an individual's response to xenobiotics, and there has been an explosion in information on sulfotransferase polymorphisms and their functional consequences, including the influence of SULT1A1 genotype on susceptibility to colorectal and breast cancer. Finally, the first gene knockout experiments with SULTs have recently been described, with the generation of estrogen sulfotransferase deficient mice in which reproductive capacity is compromised. Our improved understanding of these enzymes will have significant benefits in such diverse areas as drug design and development, cancer susceptibility, reproduction and development. (+info)
Pharmacogenetic approaches to hypertension therapy: design and rationale for the Genetics of Hypertension Associated Treatment (GenHAT) study.
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The Genetics of Hypertension Associated Treatment (GenHAT) study will determine whether variants in hypertension susceptibility genes interact with antihypertensive medication to modify coronary heart disease (CHD) risk in hypertensives. GenHAT is an ancillary study of the Antihypertensive and Lipid Lowering Treatment to Prevent Heart Attack Trial, ALLHAT, a double-blind, randomized trial of 42 418 hypertensives, 55 years of age or older, with systolic or diastolic hypertension and one or more risk factors for cardiovascular disease. About 50% are non-white, and about half are female. ALLHAT completes follow-up in March 2002. GenHAT is typing variants in hypertension genes; completion of genotyping is scheduled for 2003. Analysis of gene-treatment interactions in relation to outcomes include CHD, stroke, heart failure, and blood pressure lowering. To our knowledge, GenHAT is the largest pharmacogenetic study ever conducted. An added strength is its ability to link gene-treatment interactions with important clinical outcomes across diverse ethnic and gender groups. (+info)
Pharmacogenetic analysis of adverse drug effect reveals genetic variant for susceptibility to liver toxicity.
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A retrospective pharmacogenetic study was conducted to identify possible genetic susceptibility factors in patients in whom the administration of the anti-Parkinson drug, tolcapone (TASMAR), was associated with hepatic toxicity. We studied 135 cases of patients with elevated liver transaminase levels (ELT) of >/=1.5 times above the upper limit of normal, in comparison with matched controls that had also received the drug but had not experienced ELT. DNA samples were genotyped for 30 previously described or newly characterized bi-allelic single nucleotide polymorphisms (SNPs), representing 12 candidate genes selected based on the known metabolic pathways involved in the tolcapone elimination. SNPs located within the UDP-glucuronosyl transferase 1A gene complex, which codes for the enzymes involved in the main elimination pathway of the drug, were found to be significantly associated with the occurrence of tolcapone-associated ELTs. (+info)
Deconstruction of p53 functions and regulation.
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The 11th international p53 workshop was held in Barcelona, Spain, May 15-18, 2002. The p53 workshop was organized by Carlos Cordon-Cardo (Memorial Sloan Kettering, New York). The workshop included 46 oral presentations and 206 posters. (+info)