Amber L. Beitelshees

Pharmacokinetics and CYP2D6 genotypes do not predict metoprolol adverse events or efficacy in hypertension

β‐Blocker use can be associated with adverse effects that may have an impact on adherence or harm patients. The commonly prescribed β‐blocker metoprolol is metabolized by the polymorphic cytochrome P450 (CYP) 2D6 enzyme, resulting in widely variable drug exposure. We investigated whether metoprolol plasma concentrations, CYP2D6 polymorphisms, or genotype‐derived phenotype was associated with adverse effects or efficacy in patients with hypertension.

Pharmacogenomics of antihypertensive drugs : Rationale and design of the Pharmacogenomic Evaluation of Antihypertensive Responses (PEAR) study

BACKGROUND Selection of antihypertensive therapy is often empiric, and use of genetic information to guide drug therapy selection holds future promise. TRIAL DESIGN The objective of this trial is to identify the genetic determinants of the antihypertensive and adverse metabolic responses to a thiazide diuretic (hydrochlorothiazide), a beta-blocker (atenolol), and their combination. This will be accomplished through candidate gene and genome-wide association approaches. Individuals with uncomplicated hypertension (N = 800), with ages 17 and 65 years, are being enrolled. Current antihypertensive therapy is discontinued, and hypertension is confirmed, along with collection of other baseline data. Subjects are then randomized to either hydrochlorothiazide or atenolol, with 1 dose titration step, followed by assessment of response to therapy after at least 6 weeks on the target dose. Those with blood pressure >120/70 mm Hg have the second drug added, with similar dose titration and response assessment procedures. Data collected include home, office, and 24-hour ambulatory blood pressure. Biological samples collected in the fasting state include plasma, serum, DNA (buffy coat), and urine. Epstein-Barr virus transformed lymphocyte cell lines are also being created. CONCLUSIONS Pharmacogenetic-guided therapy holds clinical potential for hypertension, but the literature in the field is limited. This trial will add substantially to our understanding of the genetic determinants of antihypertensive and adverse metabolic responses to 2 commonly used antihypertensive drug classes.

Synergistic polymorphisms of β1 and α2C-adrenergic receptors and the influence on left ventricular ejection fraction response to β-blocker therapy in heart failure

Objectives The Arg389Gly polymorphism (Arg389Gly) in the &bgr;1-adrenergic receptor gene (ADRB1) has been associated with improvement in left-ventricular remodeling with &bgr;-blocker treatment. One study of risk for heart failure suggested a synergistic effect of ADRB1 Arg389Gly with the insertion/deletion polymorphism in the &agr;2C-adrenergic receptor gene (ADRA2C). We tested whether the ADRA2C insertion/deletion polymorphism was associated with &bgr;-blocker response in heart failure, either alone or in combination with the ADRB1Arg389Gly polymorphism. Methods Fifty-four &bgr;-blocker naive heart failure patients underwent echocardiography before and after 5–6 months of metoprolol CR/XL therapy. Multivariant linear regression modeling was performed to assess the impact of genotypes and other variables on changes in left-ventricular function in response to metoprolol therapy. Results Deletion carriers had a significantly greater negative chronotropic response. Predictors of the end of study ejection fraction were baseline ejection fraction, deletion carrier status and Arg389Arg genotype. Patients with Arg389Arg/Del-carrier status showed the greatest ejection fraction increase with metoprolol CR/XL. Adjusting for baseline ejection fraction, final S-metoprolol plasma concentration and race, final ejection fraction in patients with this genotype combination was significantly higher than all other genotype combination groups. Conclusion ADRB1 and ADRA2C polymorphisms synergistically influence the ejection fraction response to &bgr;-blocker therapy of heart failure patients.

Plasma Renin Activity Predicts Blood Pressure Responses to β-Blocker and Thiazide Diuretic as Monotherapy and Add-On Therapy for Hypertension

BACKGROUND Age and race categories or renin profiling have been recommended to predict blood pressure responses to monotherapy with a beta-blocker or thiazide diuretic. Whether these or other characteristics predict blood pressure responses when the drugs are administered as add-on therapy is uncertain. METHODS We evaluated predictors of blood pressure response in 363 men and women < or =65 years of age with primary hypertension (152 blacks, 211 whites), 86 of whom (24%) were untreated and 277 of whom (76%) were withdrawn from previous antihypertensive drugs before randomization to either atenolol followed by addition of hydrochlorothiazide (N = 180) or hydrochlorothiazide followed by addition of atenolol (N = 183). Responses were determined by home blood pressure averages before and after each drug administration. Race, age, plasma renin activity, and other characteristics including pretreatment blood pressure levels were incorporated into linear regression models to quantify their contributions to prediction of blood pressure responses. RESULTS Plasma renin activity and pretreatment blood pressure level consistently contributed to prediction of systolic and diastolic responses to each drug administered as mono- and as add-on therapy. Higher plasma renin activity was consistently associated with greater blood pressure responses to atenolol and lesser responses to hydrochlorothiazide. The predictive effects of plasma renin activity were statistically independent of race, age, and other characteristics. CONCLUSIONS Plasma renin activity and pretreatment blood pressure level predict blood pressure responses to atenolol and hydrochlorothiazide administered as mono- and as add-on therapy in men and women < or =65 years of age.

Genomic Association Analysis of Common Variants Influencing Antihypertensive Response to Hydrochlorothiazide

To identify novel genes influencing blood pressure response to thiazide diuretic therapy for hypertension, we conducted genome-wide association meta-analyses of ≈1.1 million single-nucleotide polymorphisms in a combined sample of 424 European Americans with primary hypertension treated with hydrochlorothiazide from the Pharmacogenomic Evaluation of Antihypertensive Responses study (n=228) and the Genetic Epidemiology of Responses to Antihypertensive study (n=196). Polymorphisms associated with blood pressure response at P<10–5 were tested for replication of the associations in independent samples of hydrochlorothiazide-treated European hypertensives. The rs16960228 polymorphism in protein kinase C, &agr; replicated for same-direction association with diastolic blood pressure response in the Nordic Diltiazem study (n=420) and the Genetics of Drug Responsiveness in Essential Hypertension study (n=206), and the combined 4-study meta-analysis P value achieved genome-wide significance (P=3.3×10−8). Systolic or diastolic blood pressure responses were consistently greater in carriers of the rs16960228 A allele than in GG homozygotes (>4/4 mm Hg) across study samples. The rs2273359 polymorphism in the GNAS-EDN3 region also replicated for same-direction association with systolic blood pressure response in the Nordic Diltiazem study, and the combined 3-study meta-analysis P value approached genome-wide significance (P=5.5×10−8). The findings document clinically important effects of genetic variation at novel loci on blood pressure response to a thiazide diuretic, which may be a basis for individualization of antihypertensive drug therapy and identification of new drug targets.

KCNMB1 genotype influences response to verapamil SR and adverse outcomes in the INternational VErapamil SR/Trandolapril STudy (INVEST)

Objectives We sought to determine whether polymorphisms in the large-conductance calcium and voltage-dependent potassium (BK) channel &bgr;1 subunit gene, KCNMB1, are associated with blood pressure response to verapamil SR or adverse outcomes in the GENEtic substudy of the INternational VErapamil SR/trandolapril STudy (INVEST-GENES). Background KCNMB1 is involved in calcium sensitivity and hypertension. The association between variability in KCNMB1 and calcium antagonist response, however, has not been assessed. Methods Genetic samples were collected from 5979 patients in INVEST. Blood pressure response to verapamil SR and time to achieve blood pressure control was assessed in relation to Glu65Lys and Val110Leu genotypes. The primary outcome (all cause mortality, nonfatal myocardial infarction or nonfatal stroke) was compared between genotype groups, and interaction with verapamil SR therapy was assessed. Results Systolic blood pressure response to verapamil SR did not differ by KCNMB1 genotype. Lys65 variant carriers, however, achieved blood pressure control earlier than Glu65Glu individuals [1.47 (interquartile ratio 2.77) versus 2.83 (interquartile ratio 4.17) months, P=0.01] and were less likely to require multiple drugs at the time of blood pressure control (adjusted odds ratio 0.43, 95% confidence interval 0.19–0.95). Leu110 variant carriers had a reduced risk of primary outcome (hazard ratio 0.68, 95% confidence interval 0.47–0.998). Subgroup analysis revealed this finding to be more pronounced in verapamil SR-assigned patients (hazard ratio 0.587, 95% confidence interval 0.33–1.04) compared with atenolol-assigned patients (hazard ratio 0.946, 95% confidence interval 0.56–1.59). No difference was seen in the occurrence of the primary outcome compared by codon 65 genotype. Conclusions Our findings suggest that KCNMB1 genotype influences responsiveness to verapamil SR and risk of adverse cardiovascular outcomes.

Genetic Variation in PEAR1 Is Associated With Platelet Aggregation and Cardiovascular Outcomes

Background—Aspirin or dual antiplatelet therapy with aspirin and clopidogrel is a standard therapy for patients who are at increased risk for cardiovascular events. However, the genetic determinants of variable response to aspirin (alone and in combination with clopidogrel) are not known. Methods and Results—We measured ex vivo platelet aggregation before and after dual antiplatelet therapy in individuals (n=565) from the Pharmacogenomics of Anti-Platelet Intervention (PAPI) Study and conducted a genome-wide association study of drug response. Significant findings were extended by examining genotype and cardiovascular outcomes in 2 independent aspirin-treated cohorts: 227 percutaneous coronary intervention patients and 1000 patients of the International Verapamil SR/Trandolapril Study (INVEST) Genetic Substudy (INVEST-GENES). Results from the genome-wide association study revealed a strong association between single-nucleotide polymorphisms on chromosome 1q23 and post–dual antiplatelet therapyplatelet aggregation. Further genotyping revealed rs12041331 in the platelet endothelial aggregation receptor-1 (PEAR1) gene to be most strongly associated with dual antiplatelet therapy response (P=7.66×10−9). In white and black patients undergoing percutaneous coronary intervention, A-allele carriers of rs12041331 were more likely to experience a cardiovascular event or death compared with GG homozygotes (hazard ratio, 2.62; 95% confidence interval, 0.96–7.10; P=0.059; and hazard ratio, 3.97; 95% confidence interval, 1.10–14.31; P=0.035, respectively). In aspirin-treated INVEST-GENES patients, rs12041331 A-allele carriers had significantly increased risk of myocardial infarction compared with GG homozygotes (odds ratio, 2.03; 95% confidence interval, 1.01–4.09; P=0.048). Conclusion—Common genetic variation in PEAR1 may be a determinant of platelet response and cardiovascular events in patients on aspirin alone or in combination with clopidogrel. Clinical Trial Registration—URL: http://www.clinicaltrials.gov. Unique identifiers: NCT00799396 and NCT00370045

Pharmacometabolomics reveals racial differences in response to atenolol treatment.

Antihypertensive drugs are among the most commonly prescribed drugs for chronic disease worldwide. The response to antihypertensive drugs varies substantially between individuals and important factors such as race that contribute to this heterogeneity are poorly understood. In this study we use metabolomics, a global biochemical approach to investigate biochemical changes induced by the beta-adrenergic receptor blocker atenolol in Caucasians and African Americans. Plasma from individuals treated with atenolol was collected at baseline (untreated) and after a 9 week treatment period and analyzed using a GC-TOF metabolomics platform. The metabolomic signature of atenolol exposure included saturated (palmitic), monounsaturated (oleic, palmitoleic) and polyunsaturated (arachidonic, linoleic) free fatty acids, which decreased in Caucasians after treatment but were not different in African Americans (p<0.0005, q<0.03). Similarly, the ketone body 3-hydroxybutyrate was significantly decreased in Caucasians by 33% (p<0.0001, q<0.0001) but was unchanged in African Americans. The contribution of genetic variation in genes that encode lipases to the racial differences in atenolol-induced changes in fatty acids was examined. SNP rs9652472 in LIPC was found to be associated with the change in oleic acid in Caucasians (p<0.0005) but not African Americans, whereas the PLA2G4C SNP rs7250148 associated with oleic acid change in African Americans (p<0.0001) but not Caucasians. Together, these data indicate that atenolol-induced changes in the metabolome are dependent on race and genotype. This study represents a first step of a pharmacometabolomic approach to phenotype patients with hypertension and gain mechanistic insights into racial variability in changes that occur with atenolol treatment, which may influence response to the drug.

Cost-Effectiveness of Cytochrome P450 2C19 Genotype Screening for Selection of Antiplatelet Therapy with Clopidogrel or Prasugrel

For example, scenario B has an ICER, as reported in Table 2, of –

Impact of Abdominal Obesity on Incidence of Adverse Metabolic Effects Associated With Antihypertensive Medications

11,710 (95% confidence interval [CI] –11,480 to –