Influence of CYP2D6 Genotype on Metoprolol Plasma Concentration and β-Adrenergic Inhibition During Long-Term Treatment

Comparison between the ECG Outcomes of Metoprolol and Bisoprolol

BACKGROUND

Beta-blockers are essential agents in the management of cardiovascular diseases, such as heart failure, acute myocardial infarction (MI), and cardiac arrhythmias. However, there are diurnal variations in the cardioprotective effects of the subgroups as a result of their different pharmacokinetic, pharmacodynamic, and pharmacogenetic profiles.

OBJECTIVES

We aimed to compare metoprolol and bisoprolol in terms of electrocardiogram (ECG) outcomes.

METHODS

A retrospective cross-sectional study was conducted at Prince Sultan Cardiac Center. The trial included 404 patients who met the inclusion criteria (204 in the metoprolol arm and 200 in the bisoprolol arm). Using case record forms that had already been created, information, such as patient demographics, medical histories, and treatment histories, was taken from their medical files. The most recent ECG records were also gathered. The ethical approval for this study was obtained from Qassim ethical committee (approval number: 45-44-902).

RESULTS

There was no significant difference found between the patients in both arms in terms of baseline characteristics, age, or sex.

CONCLUSION

In this retrospective cross-sectional study, we have compared the effects of metoprolol and bisoprolol beta blockers on ECG changes. The findings have indicated no difference between metoprolol and bisoprolol groups in terms of all ECG readings, particularly PR/ms, QTC-ms, and ventricular rate. Further studies are required to confirm these findings.

Preemptive Pharmacogenetic-Guided Metoprolol Management for Postoperative Atrial Fibrillation in Cardiac Surgery: The Preemptive Pharmacogenetic-Guided Metoprolol Management for Atrial Fibrillation in Cardiac Surgery Pilot Trial

OBJECTIVES

To test the hypothesis that implementation of a cytochrome P-450 2D6 (CYP2D6) genotype-guided perioperative metoprolol administration will reduce the risk of postoperative atrial fibrillation (AF), the authors conducted the Preemptive Pharmacogenetic-Guided Metoprolol Management for Atrial Fibrillation in Cardiac Surgery pilot study.

DESIGN

Clinical pilot trial.

SETTING

Single academic center.

PARTICIPANTS

Seventy-three cardiac surgery patients.

MEASUREMENTS AND MAIN RESULTS

Patients were classified as normal, intermediate, poor, or ultrarapid metabolizers after testing for their CYP2D6 genotype. A clinical decision support tool in the electronic health record advised providers on CYP2D6 genotype-guided metoprolol dosing. Using historical data, the Bayesian method was used to compare the incidence of postoperative AF in patients with altered metabolizer status to the reference incidence. A logistic regression analysis was performed to study the association between the metabolizer status and postoperative AF while controlling for the Multicenter Study of Perioperative Ischemia AF Risk Index. Of the 73 patients, 30% (n = 22) developed postoperative AF; 89% (n = 65) were normal metabolizers; 11% (n = 8) were poor/intermediate metabolizers; and there were no ultrarapid metabolizer patients identified. The estimated rate of postoperative AF in patients with altered metabolizer status was 30% (95% CI 8%-60%), compared with the historical reference incidence (27%). In the risk-adjusted analysis, there was insufficient evidence to conclude that modifying metoprolol dosing based on poor/intermediate metabolizer status was associated significantly with the odds of postoperative AF (odds ratio 0.82, 95% CI 0.15-4.55, p = 0.82).

CONCLUSIONS

A CYP2D6 genotype-guided metoprolol management was not associated with a reduction of postoperative AF after cardiac surgery.

Acute liver injury induced by drug interaction between dacomitinib and metoprolol due to the inhibition of CYP2D6 by dacomitinib

Introduction

In recent years, oral antineoplastic agents are commonly used in antitumor therapy. The interaction between drugs may affect the efficacy of drugs or lead to adverse reactions. We describe the case of a patient who presented acute liver injury, possibly induced by the concomitant use of metoprolol and dacomitinib.

Case report

A 62-year-old male patient with non-small cell lung cancer was admitted for anti-cancer treatment. He regularly took metoprolol tartrate 12.5 mg, 2/day for hypertension. He was treated with dacomitinib according to EGFR Exon21 L858R positive. After 3 days of dacomitinib, the patient's alanine aminotransferase (ALT) and glutathione aminotransferase (AST) increased, and the heart rate and systolic blood pressure of the patient decreased significantly. The patient was diagnosed with acute liver injury.

Management and outcomes

Dacomitinib was discontinued and glutathione, magnesium isoglycyrrhizinate were given to treat acute liver injury. Two days after discontinued dacomitinib, the patient's heart rate increased, but the ALT and AST of the patient elevated again. Metoprolol tartrate was subsequently discontinued and the ALT and AST gradually decreased and the patient discharged from the hospital eight days later with his liver function improved.

Discussion

To our knowledge, this is the first case in the literature of acute liver injury possibly induced by the interaction between metoprolol and dacomitinib. The interaction most likely arose because dacomitinib is a CYP2D6 strong inhibitor and could therefore impair the metabolism of metoprolol (a CYP2D6 substrate) and increase its serum concentration. Therefore, hepatic function should be carefully monitored in patients treated with dacomitinib and metoprolol and other inhibitors or inducers of CYP2D6.

The effect of rs776746 polymorphism in the <i>CYP3A5</i> gene on heart rate when using bisoprolol in patients with acute coronary syndrome

Aim. The aim of this work was to study the occurrence of the rs776746 allelic variant of the CYP3A5 gene and its effect on heart rate (HR) when using bisoprolol in patients hospitalized with acute coronary syndrome (ACS).

Materials and methods. The study included patients with ACS who were prescribed bisoprolol for clinical indications. All patients underwent molecular genetic testing. In order to evaluate the effectiveness of the therapy with bisoprolol, all patients underwent Holter electrocardiogram (ECG) monitoting on days 10, the following parameters were assessed: minimum, average, maximum heart rate and heart rate during an exercise test. The stress test was performed as a ladder test.

Results. The study involved 97 patients (63,5±10,5 years), including 60 men and 37 women. The frequency of occurrence of the desired alleles of the CYP3A5 gene was: CYP3A5*3 - 93%, and CYP3A5*1 - 7%, which corresponds to its prevalence in the European population. 84 carriers of the CYP3A5*3*3 genotype (87%), 12 heterozygous carriers of the *1 allele (12%) and one patient with the *1*1 genotype (1%) were identified. In order to search for differences in the effects of bisoprolol depending on the genetically predetermined activity of CYP3A5, we divided the general group of patients into two subgroups: subgroup 1 (CYP3A5*3*3), represented by carriers of the genotype associated with the synthesis of the inactive form of CYP3A5, and subgroup 2 (CYP3A5*1*3 and CYP3A5*1*1), represented by carriers of at least one allele encoding the synthesis of a fully functional protein CYP3A5, coupled with an increased metabolic rate. Patients did not differ in clinical and demographic characteristics. By the time of daily ECG monitoring, both groups reached comparable heart rate values. In carriers of at least one CYP3A5*1 allele (n = 13), associated with an increased metabolic rate, the daily dose of bisoprolol on the 10th day of hospitalization was significantly higher (p <0.05). The only carrier of the homozygous CYP3A5 *1*1 variant receives bisoprolol at a daily dose of 10 mg. Taking into account the close to significant differences in glomerular filtration rate (GFR) in patients in the groups with the studied genetic variants, and the known eliminating role of the kidneys for bisoprolol, a linear regression model was built with the inclusion of factors that could affect the dose of bisoprolol: GFR, functional class of chronic heart failure, gender, age, number of simultaneously assigned CYP3A5 substrates. Of the parameters listed, only the CYP3A5 genotype significantly predicted the dose of bisoprolol (F=8.5; p<0.005; R2=0.096).

Conclusion. In this study, it was demonstrated for the first time that patients with different genetic variants of CYP3A5, in particular with respect to the rs776746 polymorphism, may differ in individual requirements for the dose of bisoprolol.

Sex-Based Difference in the Effect of Metoprolol on Heart Rate and Bradycardia in a Population-Based Setting

Background: Metoprolol, a beta-blocker, is used to reduce the heart rate. Although it has been demonstrated that the metoprolol plasma concentration is higher in women than in men, the same dose is recommended. In this study, we investigated whether the metoprolol concentration was associated with a stronger heart-rate reduction and bradycardia in women than in men. Methods: This study is part of the Rotterdam Study (RS), a population-based prospective cohort study. Blood samples from a random subset of 2000 participants were used to assess metoprolol plasma levels. An analysis of heart rate (beats per minute, bpm) and bradycardia (<60 bpm) was performed in metoprolol users with an ECG at the day of blood collection to study sex-specific differences in heart rate and the risk of bradycardia. Results: In total, 40 women and 39 men were included. There was a statistically significant association between metoprolol concentration and heart rate in women (p-value: 0.014) but not in men (p-value: 0.639). Furthermore, women in the highest concentration group had a more than 15-times-higher risk of bradycardia than women in the lowest concentration group (OR = 15.6; 95% CI = 1.1, 217.3); however, this was not seen in men (OR = 1.3; 95% CI = 0.1, 12.4). After adjustment for age, BMI, time between blood sample and ECG, hypertension, myocardial infarction, heart failure, atrial fibrillation, digoxin use, and calcium channel blocker use, the association between concentration and bradycardia in women remained statistically significant. Conclusions: Women, but not men, had a statistically significantly lower heart rate at higher metoprolol plasma concentration and a statistically significantly increased risk of bradycardia.

Impact of the CYP2D6 Genotype on Metoprolol Tolerance and Adverse Events in Elderly Chinese Patients With Cardiovascular Diseases

The latest consensus has changed CYP2D6 genotyping among Chinese population, while its impact on metoprolol tolerance and adverse events in elderly Chinese patients with cardiovascular diseases remains unclear. In this study, we prospectively included elderly patients who started metoprolol treatment for cardiovascular indications. According to the latest consensus on CYP2D6 genotype-to-phenotype translation, the patients were categorized as normal, intermediate, or poor metabolizers (NMs, IMs, or PMs, respectively) by detecting the presence of the CYP2D6*1, *2, *5, *10, and *14. Logistic regression model was used to analyze the correlation between the CYP2D6 phenotype and incidence of adverse events, which were assessed over a 12-week period. In this study, there were 651 (62.7%) NMs, 385 (37.1%) IMs, and 3 (0.3%) PMs. After 12 weeks of follow-up, compared with NMs, IMs had the lower maintenance dose [50.0 (25.0–50.0) mg/day vs. 25.0 (25.0–50.0) mg/day, p < 0.001] and lower weight-adjusted maintenance doses (0.52 ± 0.25 mg/day/kg vs. 0.42 ± 0.22 mg/day/kg, p < 0.001), and had higher incidence of postural hypotension (6.0% vs. 10.9%, p = 0.006), bradycardia (21.5% vs. 28.6%, p = 0.011), asystole (0.8% vs. 3.1%, p = 0.009) and syncope (2.0% vs. 6.2%, p = 0.001). In logistic regression model, the overall incidence of adverse events was 1.37-fold larger in IMs than in NMs (odds ratio = 1.37, 95% confidence interval = 1.05–1.79, p = 0.021). We conclude that IMs have lower tolerance and higher incidence of metoprolol-related adverse events than NMs in elderly Chinese patients with cardiovascular diseases. CYP2D6 genotyping is justifiable in elderly patients to minimize the risk of adverse events and ensure the benefits of metoprolol.

Chromosomal Region 11p14.1 is Associated with Pharmacokinetics and Pharmacodynamics of Bisoprolol

Purpose

Bisoprolol is a widely used beta-blocker in patients with cardiovascular diseases. As with other beta-blockers, there is variability in response to bisoprolol, but the underlying reasons for this have not been clearly elucidated. Our aim was to investigate genetic factors that affect bisoprolol pharmacokinetics (PK) and pharmacodynamics (PD), and potentially the clinical outcomes.

Patients and Methods

Patients with non-ST elevation acute coronary syndrome were recruited prospectively on admission to hospital and followed up for up to 2 years. Patients from this cohort who were on treatment with bisoprolol, at any dose, had bisoprolol adherence data and a plasma sample, one month after discharge from index hospitalisation were included in the study. Individual bisoprolol clearance values were estimated using population pharmacokinetic modeling. Genome-wide association analysis after genotyping was undertaken using an Illumina HumanOmniExpressExome-8 v1.0 BeadChip array, while CYP2D6 copy number variations were determined by PCR techniques and phenotypes for CYP2D6 and CYP3A were inferred from the genotype. GWAS significant SNPs were analysed for heart rate response to bisoprolol in an independent cohort of hypertensive subjects.

Results

Six hundred twenty-two patients on bisoprolol underwent both PK and genome wide analysis. The mean (IQR) of the estimated clearance in this population was 13.6 (10.0-18.0) L/h. Bisoprolol clearance was associated with rs11029955 (p=7.17×10-9) mapped to the region of coiled-coil domain containing 34 region (CCDC34) on chromosome 11, and with rs116702638 (p=2.54×10-8). Each copy of the minor allele of rs11029955 was associated with 2.2 L/h increase in clearance. In an independent cohort of hypertensive subjects, rs11029955 was associated with 24-hour heart rate response to 4-week treatment with bisoprolol (p= 9.3×10-5), but not with rs116702638.

Conclusion

A novel locus on the chromosomal region 11p14.1 was associated with bisoprolol clearance in a real-world cohort of patients and was validated in independent cohort with a pharmacodynamic association.

Influence of CYP2D6 and CYP3A5 Polymorphisms on the Pharmacokinetics and Pharmacodynamics of Bisoprolol in Hypertensive Chinese Patients

Purpose: This study was performed to investigate the effects of common polymorphisms in CYP2D6 and CYP3A5 on the plasma concentrations and antihypertensive effects of bisoprolol in hypertensive Chinese patients. Methods: One hundred patients with essential hypertension were treated with open-label bisoprolol 2.5 mg daily for 6 weeks. Clinic blood pressure (BP) and ambulatory BP (ABP) were measured after the placebo run-in and after 6 weeks treatment. Peak plasma concentrations of bisoprolol were measured at 3 h after the first dose and 3 h after the dose after 6 weeks treatment. Trough levels were measured before the dose after 6 weeks treatment. Bisoprolol plasma concentrations were measured with a validated liquid chromatography tandem mass spectrometry method. Six common polymorphisms in CYP2D6 and the CYP3A5 ^* 3 polymorphism were genotyped by TaqMan® assay. Results: After 6 weeks of treatment, clinic BP and heart rate were significantly reduced by 14.3 ± 10.9/8.4 ± 6.2 mmHg (P < 0.01) and 6.3 ± 7.6 BPM (P < 0.01), respectively. Similar reductions were seen in ABP values. Bisoprolol plasma concentration at 3 h after the first dose and 3 h post-dose after 6 weeks of treatment were significantly associated with baseline body weight (P < 0.001) but there was no significant effect of the CYP2D6 and CYP3A5 polymorphisms on these or the trough plasma concentrations. There was no significant association of the CYP2D6 and CYP3A5 polymorphisms or plasma bisoprolol concentrations with the clinic BP or ABP responses to bisoprolol. Conclusion: Bisoprolol 2.5 mg daily effectively reduced BP and HR. The common polymorphisms in CYP2D6 that were examined and the CYP3A5 ^* 3 polymorphism appear to have no benefit in predicting the hemodynamic response to bisoprolol in these patients.

Examination of Metoprolol Pharmacokinetics and Pharmacodynamics Across CYP2D6 Genotype-Derived Activity Scores

Recent CYP2D6 phenotype standardization efforts by CYP2D6 activity score (AS) are based on limited pharmacokinetic (PK) and pharmacodynamic (PD) data. Using data from two independent clinical trials of metoprolol, we compared metoprolol PK and PD across CYP2D6 AS with the goal of determining whether the PK and PD data support the new phenotype classification. S‐metoprolol apparent oral clearance (CLo), adjusted for clinical factors, was correlated with CYP2D6 AS (P < 0.001). The natural log of CLo was lower with an AS of 1 (7.6 ± 0.4 mL/minute) vs. 2–2.25 (8.3 ± 0.6 mL/minute; P = 0.012), similar between an AS of 1 and 1.25–1.5 (7.8 ± 0.5 mL/minute; P = 0.702), and lower with an AS of 1.25–1.5 vs. 2–2.25 (P = 0.03). There was also a greater reduction in heart rate with metoprolol among study participants with AS of 1 (−10.8 ± 5.5) vs. 2–2.25 (−7.1 ± 5.6; P < 0.001) and no significant difference between those with an AS of 1 and 1.25–1.5 (−9.2 ± 4.7; P = 0.095). These data highlight linear trends among CYP2D6 AS and metoprolol PK and PD, but inconsistencies with the phenotypes assigned by AS based on the current standards. Overall, this case study with metoprolol suggests that utilizing CYP2D6 AS, instead of collapsing AS into phenotype categories, may be the most precise approach for utilizing CYP2D6 pharmacogenomics in clinical practice.

Bisoprolol responses (PK/PD) in hypertensive patients: A cytochrome P450 (CYP) 2D6 targeted polymorphism study

BACKGROUND

Bisoprolol is an effective β1-adrenergic blocker, an inter-individual genetic variability was recorded in its response. This study aimed at investigating the association of CYP2D6*2A (rs1080985) and CYP2D6*10 (rs1065852) single-nucleotide polymorphism (SNP) with Bisoprolol response in cardiac patients attending King Abdulaziz University Hospital, Jeddah, Kingdom of Saudi Arabia.

PATIENTS AND METHODS

In the study, 107 patients were enrolled. Five mL of venous blood was collected from each patient and genotyping for CYP2D6*2A and CYP2D6*10 using Vivid® CYP2D6 Green Screening Kit (Life Technologies, USA). Response to Bisoprolol was evaluated through assessment of diastolic and systolic blood pressure and by measuring Bisoprolol plasma level using triple quad mass spectrometer (TQ-MS).

RESULTS

All patients were found to carry homozygous wild type CYP2D6*10 (GG) and none were carrying heterozygous (GA) or mutant homozygous (AA) genotype. CYP2D6*2A allele was detected in the homozygous wild type (GG) in 70 out of 107 patients, the heterozygous (GC) in 19 patients, and the homozygous mutant (CC) in 18 patients with minor allele frequency (MAF) of 25.7%. The plasma concentrations of Bisoprolol in CC carriers were significantly lower than those in GG & CC carriers by 25%, and 51%; respectively. Higher systolic and diastolic blood pressures were also observed in CC carriers than GG and CC carriers.

CONCLUSION

There is a possible association of CYP2D6*2A genotype with plasma concentration of bisoprolol. This could provide a helpful tool to choose the optimum dose for bisoprolol, depending on the patient's genotyping, in order to increase effectiveness and ameliorate its toxicity.

Population pharmacokinetic analysis of bisoprolol in type 2 diabetic patients with hypertension

PURPOSE

Given that it has been reported that type 2 diabetes mellitus may affect the pharmacokinetics of a large number of drugs and that there are still no published population pharmacokinetic (PopPK) analyses in routinely treated patients with hypertension and type 2 diabetes mellitus as comorbid condition, the aim of this study was to determine PK variability of bisoprolol in 70 Serbian patients using the PopPK approach.

METHODS

PopPK analysis was conducted using a nonlinear mixed effects model (NONMEM), version 7.3.0 (Icon Development Solutions). In our patients, a total daily dose of bisoprolol ranged from 1.25 to 10 mg. The drug was administrated orally as a single daily dose or in two divided doses per day.

RESULTS

A wide range of the drug concentrations were noted (1-103 ng/mL) in the population consisted of the adult patients with type 2 diabetes mellitus. From a total of 21 separately assessed covariates, our results indicated that only creatinine clearance could have a potential impact on the variability of the clearance of bisoprolol.

CONCLUSION

Routine assessment of renal function should be carried out before the initiation of treatment with bisoprolol in order to individualize the dose and to prevent possible accumulation and adverse drug reactions.

Population Pharmacokinetic Analysis of Bisoprolol in Patients With Acute Coronary Syndrome

To date, many questions about the extent and cause of pharmacokinetic (PK) variability of even the most widely studied and prescribed β1-adrenergic receptor blockers, such as metoprolol and bisoprolol, remain unanswered. Given that there are still no published population pharmacokinetic (PopPK) analyses of bisoprolol in routinely treated patients with acute coronary syndrome (ACS), the aim of this study was to determine its PK variability in 71 Serbian patients with ACS. PopPK analysis was conducted using a nonlinear mixed-effects model (NONMEM), version 7.3.0 (Icon Development Solutions). In each patient, the same formulation of bisoprolol was administered once or twice daily at a total daily dose of 0.625-7.5 mg. We separately assessed the effects of 31 covariates on the PKs of bisoprolol, and our results indicated that only 2 covariates could have possible influence on the variability of the clearance of bisoprolol: the mean daily dose of the drug and smoking habits of patients. These findings suggest that possible autoinduction of drug metabolism by higher total daily doses and induction of cytochrome P450 isoform 3A4 (CYP3A4) by cigarette smoke in liver could be the potential causes of increased total clearance of bisoprolol in patients with ACS.

Beta-blockers in COPD: A systematic review based on recent research

Chronic obstructive pulmonary disease (COPD) with cardiovascular complications is very common. Due to fear of exacerbating airway spasm, β-blockers are rarely used in such patients. Many observational studies suggest that β-blockers can reduce the disease progression and the risk of mortality in patients with COPD, but lack of confirmation from randomized controlled trials. This article reviews the application of β-blockers in patients with COPD based on the results of the latest published randomized controlled trials.

CYP2D6 polymorphism and its impact on the clinical response to metoprolol: A systematic review and meta-analysis

AIMS

CYP2D6 genetic polymorphisms are associated with metoprolol pharmacokinetics. Whether the clinical response to metoprolol is also affected remains uncertain.

METHODS

We conducted a systematic review on the effects of CYP2D6 polymorphism on the clinical response to metoprolol. Searches were conducted using MEDLINE. Meta-analyses were performed on the impact of CYP2D6-inferred phenotypes on heart rate (HR) reduction, diastolic (DBP) and systolic (SBP) blood pressure reduction, average daily doses, all-type adverse events and bradycardia.

RESULTS

Our qualitative assessment indicated inconsistent results in individual studies and endpoints, but CYP2D6 poor metabolizers (PM) generally presented a greater reduction in HR. The meta-analysis of 15 studies, including a total of 1146 individuals, found a reduction in HR of 3 beats/min (P = .017), and of SBP and DBP by 3 mmHg (P = .0048) for PM compared to non-PM individuals using similar metoprolol doses. Bradycardia appeared more frequent by 4-fold for PM, although significant heterogeneity was observed regarding bradycardia, which limits the scope of this finding.

CONCLUSION

Patients without any CYP2D6 metabolic capacities appear to have increased reduction in DBP, HR and SBP during metoprolol treatment and may be at a higher risk of bradycardia compared to patients with active CYP2D6 phenotypes. Further prospective data are required to determine whether CYP2D6 is associated with clinical events in patients treated with metoprolol, as well as to demonstrate the clinical utility of an individualized approach of prescribing metoprolol using CYP2D6-inferred phenotypes.

Azilsartan medoxomil

Azilsartan is used for treatment of the high blood pressure (hypertension). Reducing high blood pressure enables avoid strokes, heart attacks and problems of kidneys. Azilsartan comes under the name angiotensin receptor blocker (ARBs) as a class of drugs. It acts by relaxing blood vessels to make it easier for blood to flow. Azilsartan Medoxomil's a comprehensive profile containing the description, formulae, Elemental Analysis, Uses and application. Furthermore, methods and schemes are outlined for the preparation of the drug substance. The physical properties of the medication include constant of ionization, solubility, X-ray powder diffraction pattern, differential scanning calorimetry, thermal conduct and spectroscopic studies are investigated. The methods employed in bulk medicines and/or in pharmaceutical formulations to analyze the drug substance include spectrophotometric, electrochemical and the chromatographic methods. Other studies on this drug substance include drug stability, Pharmaceutical Applications, Mechanism of Action, Pharmacodynamics, and a Dosing Information are reviewed. At the end of this profile, there are more than sixty references were listed.

Pharmacogenomics And Hypertension: Current Insights

Hypertension is a multifactorial disease that affects approximately one billion subjects worldwide and is a major risk factor associated with cardiovascular events, including coronary heart disease and cerebrovascular accidents. Therefore, adequate blood pressure control is important to prevent these events, reducing premature mortality and disability. However, only one third of patients have the effective control of blood pressure, despite several classes of antihypertensive drugs available. These disappointing outcomes may be at least in part explained by interpatient variability in drug response due to genetic polymorphisms. To address the effects of genetic polymorphisms on blood pressure responses to the antihypertensive drug classes, studies have applied candidate genes and genome wide approaches. More recently, a third approach that considers gene-gene interactions has also been applied in hypertension pharmacogenomics. In this article, we carried out a comprehensive review of recent findings on the pharmacogenomics of antihypertensive drugs, including diuretics, β-blockers, angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers, and calcium channel blockers. We also discuss the limitations and inconsistences that have been found in hypertension pharmacogenomics and the challenges to implement this valuable approach in clinical practice.

CYP2D6 Genotype-guided Metoprolol Therapy in Cardiac Surgery Patients: Rationale and Design of the Pharmacogenetic-guided Metoprolol Management for Postoperative Atrial Fibrillation in Cardiac Surgery (PREEMPTIVE) Pilot Study

OBJECTIVES

The Preemptive Pharmacogenetic-guided Metoprolol Management for Atrial Fibrillation in Cardiac Surgery (PREEMPTIVE) pilot trial aims to use existing institutional resources to develop a process for integrating CYP2D6 pharmacogenetic test results into the patient electronic health record, to develop an evidence-based clinical decision support tool to facilitate CYP2D6 genotype-guided metoprolol administration in the cardiac surgery setting, and to determine the impact of implementing this CYP2D6 genotype-guided integrated approach on the incidence of postoperative atrial fibrillation (AF), provider, and cost outcomes.

DESIGN

One-arm Bayesian adaptive design clinical trial.

SETTING

Single center, university hospital.

PARTICIPANTS

The authors will screen (including CYP2D6 genotype) up to 600 (264 ± 144 expected under the adaptive design) cardiac surgery patients, and enroll up to 200 (88 ± 48 expected) poor, intermediate, and ultrarapid CYP2D6 metabolizers over a period of 2 years at a tertiary academic center.

INTERVENTIONS

All consented and enrolled patients will receive the intervention of CYP2D6 genotype-guided metoprolol management based on CYP2D6 phenotype classified as a poor, intermediate, extensive (normal), or ultrarapid metabolizer.

MEASUREMENTS AND MAIN RESULTS

The primary outcome will be the incidence of postoperative AF. Secondary outcomes relating to rates of CYP2D6 genotype-guided prescription changes, costs, lengths of stay, and implementation metrics also will be investigated.

CONCLUSIONS

The PREEMPTIVE pilot study is the first perioperative pilot trial to provide essential information for the design of a future, large-scale trial comparing CYP2D6 genotype-guided metoprolol management with a nontailored strategy in terms of managing AF. In addition, secondary outcomes regarding implementation, clinical benefit, safety, and cost-effectiveness in patients undergoing cardiac surgery will be examined.

Comparative research on the metabolism of metoprolol by four CYP2D6 allelic variants in vitro with LC-MS/MS

Specific study about the effect of cytochrome P450 2D6 (CYP2D6) polymorphisms on the metabolism of clinic drugs is of great significance for drug safety investigation. Here, the interaction between CYP2D6 variants (*1, *2, *10, *39) and metoprolol (MET) was intensively researched in vitro from the aspect of drug-enzyme kinetic study. To obtain quantitative data, α-hydroxymetoprolol (main metabolite of MET) was selected as an ideal analyte and an LC-MS/MS method was adopted for sample determination. Firstly, by selecting suitable internal standard and optimizing separation condition, the LC-MS/MS method was established and validated. Then, the drug-enzyme incubation system was optimized by two parameters: incubation time and amount of enzyme. Lastly, the interaction between CYP2D6 allelic variants and MET was characterized by K_m, V_max and CL_int. As a result, four CYP2D6 enzymes displayed diverse K_m or V_max towards MET and the values of CL_int showed a wide range from 8.91 to 100%. Relative to CYP2D6*1 (CL_int*1 = 100%), CYP2D6*2 demonstrated the second high catalytic activity (CL_int*2/*1 = 74.87%) while CYP2D6*39 (CL_int*39/*1 = 29.65%) and CYP2D6*10 (CL_int*10/*1 = 8.91%) showed minimal catalytic activity. This comprehensive in vitro data suggested the prominent influence of CYP2D6 polymorphisms on the metabolism of MET, which could offer valuable information for personalized administration of MET in clinic.

Pharmacogenetic testing by polymorphic markers G1846A (CYP2D6*4) and C100T (CYP2D6*10) of the CYP2D6 gene in coronary heart disease patients taking ββ-blockers in the Republic of Sakha (YAKUTIA)

Background The aim of this study was to determine carrier frequencies of the polymorphic markers G1846A (CYP2D6*4) and C100T (CYP2D6*10) of the CYP2D6 gene in coronary heart disease (CHD) patients in Russian and Yakut ethnic groups. The association between the administration of higher doses of bisoprolol and metoprolol and the carriage of these polymorphic markers related to the decreased function of the haplotype of CYP2D6 was also studied. Methods The study included 201 CHD patients (aged 66±8.7 years) receiving metoprolol in titrated dose (12.5-150 mg), bisoprolol (2.5-10 mg) or atenolol (50 mg). Ninety-three patients were Russian (30 men and 63 women), and 108 patients were Yakut (54 men and 54 women). Results In genotyping CHD patients in the Russian and Yakut ethnic groups, there was no significant difference in the prevalence rate of the polymorphic markers G1846A (10.8 vs. 10.2; p=0.871) and C100T (16.1 vs. 16.2; p=1). In patients carrying the polymorphic marker G1846A, the dose of bisoprolol was established to be lower than that in the control group (p=0.0289). Conclusions The carriage frequency of polymorphic markers, which theoretically should differ between Russians and Yakuts as representatives of two different races, in practice turned out to be the same.

Associations of polymorphisms of CYP2D6 and CYP2C9 with early onset severe pre-eclampsia and response to labetalol therapy

PURPOSE

Early onset preeclampsia (PPE) contributes to life-threatening maternal complications and fetal demise. Pharmacogenomics is a precision medicine, and metabolizing enzymes responsive to antihypertensive remains understudied. The aim of this study was to evaluate the associations of polymorphisms of cytochrome P450, family 2, subfamily D, polypeptide 6 (CYP2D6) and cytochrome P450, family 2, subfamily C, polypeptide 9 (CYP2C9) with PPE and the relationship among CYP2D6, CYP2C9 polymorphisms and response to labetalol therapy.

METHODS

Totally 105 gravidas diagnosed with PPE (case) and 103 healthy gravidas (control) were recruited between August 2013 and July 2016. Labetalol was given to control blood pressures (BP) with PPE. If labetalol administration alone did not exceed the mean dose and effectively controlled the BP, it would be considered to be valid (n = 75). Genotype and allele frequencies of CYP2C9 gene (rs1057910 and rs4918758) and CYP2D6 gene (rs1065852, rs28371725, rs35742686, and rs3892097) were analyzed by TaqMan PCR. Differences in the genotype and allele frequencies were compared between case-control groups, and the responsive and nonresponsive to labetalol in PPE.

RESULTS

Out of six variants, only CC and CT genotypes of the CYP2D6 variants (rs28371725) in PPE were significantly higher than those in the control group [18.1% (19/105) vs 14.6% (15/103); 56.2% (59/105) vs 42.7% (44/103); χ2 = 6.707]. However, there were no differences in maternal age, diastolic pressure, BMI, BW, serum triglyceride, and creatinine were observed among women with CC, CT, or TT genotype of CYP2D6 gene rs28371725 in the experimental group (all P > 0.05). Compared with the gravidas with CT or TT genotype of CYP2D6 gene rs28371725, those with CC genotype had longer gestational age [(32.5 ± 2.1) vs (29.5 ± 1.8) and (29.8 ± 2.2) weeks] and higher plasma albumin [(27.2 ± 9.3) vs (20.3 ± 10.4) and (22.5 ± 7.4) g/L], but lower systolic pressure and 24 h urine protein (LSD test, all P < 0.05). The G allele frequency in CYP2D6 gene rs1065852 nonresponsive to labetalol group was higher than that in responsive labetalol group [93.3% (56/60) vs 76.0% (114/150), χ2 = 8.351, P = 0.004].

CONCLUSIONS

The polymorphism of CYP2D6 gene rs28371725 may be associated with PPE, and the allele of G in CYP2D6 gene rs1065852 may be associated with the efficacy of labetalol in treatment of PPE.

CYP2D6 Genetic Variation and Beta-Blocker Maintenance Dose in Patients with Heart Failure

PURPOSE

This study examined whether a CYP2D6 polymorphism (CYP2D6*4) was related to beta-blocker maintenance dose in patients with heart failure.

METHODS

Logistic regression modeling was utilized in a retrospective chart-review analysis of heart-failure patients (60% Male, 90% of European descent) to assess whether CYP2D6*4 (non-functional CYP2D6 allele present in 1 of 5 individuals of European descent) is associated with maintenance dose of carvedilol (n = 65) or metoprolol (n = 33).

RESULTS

CYP2D6*4 was associated with lower maintenance dose of metoprolol (OR 0.13 [95% CI 0.02-0.75] p = 0.023), and a trend was observed between CYP2D6*4 and higher maintenance dose of carvedilol (OR 2.94 [95% CI 0.84-10.30] p = 0.093). None of the patients that carried CYP2D6*4 achieved the recommended target dose of metoprolol (200 mg/day).

CONCLUSION

Consistent with the role of CYP2D6 in the metabolism of metoprolol, the tolerated maintenance dose of metoprolol was lower in CYP2D6*4 carriers compared to non-carriers. Consistent with the role of CYP2D6 in activation of carvedilol, tolerated maintenance dose of carvedilol was higher in CYP2D6*4 carriers compared to non-carriers. Further investigation is warranted to ascertain the potential of CYP2D6 as a potential predictive biomarker of beta-blocker maintenance dose in heart failure patients.

Impact of β-blocker selectivity on long-term outcomes in congestive heart failure patients with chronic obstructive pulmonary disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is present in approximately one-third of all congestive heart failure (CHF) patients, and is a key cause of underprescription and underdosing of β-blockers, largely owing to concerns about precipitating respiratory deterioration. For these reasons, the aim of this study was to evaluate the impact of β-blockers on the long-term outcomes in CHF patients with COPD. In addition, we compared the effects of two different β-blockers, carvedilol and bisoprolol.

METHODS

The study was a retrospective, non-randomized, single center trial. Acute decompensated HF patients with COPD were classified according to the oral drug used at discharge into β-blocker (n=86; carvedilol [n=52] or bisoprolol [n=34]) and non-β-blocker groups (n=46). The primary endpoint was all-cause mortality between the β-blocker and non-β-blocker groups during a mean clinical follow-up of 33.9 months. The secondary endpoints were the differences in all-cause mortality and the hospitalization rates for CHF and/or COPD exacerbation between patients receiving carvedilol and bisoprolol.

RESULTS

The mortality rate was higher in patients without β-blockers compared with those taking β-blockers (log-rank P=0.039), and univariate analyses revealed that the use of β-blockers was the only factor significantly correlated with the mortality rate (hazard ratio: 0.41; 95% confidence interval: 0.17-0.99; P=0.047). Moreover, the rate of CHF and/or COPD exacerbation was higher in patients treated with carvedilol compared with bisoprolol (log-rank P=0.033). In the multivariate analysis, only a past history of COPD exacerbation significantly increased the risk of re-hospitalization due to CHF and/or COPD exacerbation (adjusted hazard ratio: 3.11; 95% confidence interval: 1.47-6.61; P=0.003).

CONCLUSION

These findings support the recommendations to use β-blockers in HF patients with COPD. Importantly, bisoprolol reduced the incidence of CHF and/or COPD exacerbation compared with carvedilol.

Impact of CYP2D6 polymorphisms on clinical efficacy and tolerability of metoprolol tartrate

Metoprolol is a selective β-1 adrenergic receptor blocker that undergoes extensive metabolism by the polymorphic enzyme cytochrome P450 2D6 (CYP2D6). Our objective was to investigate the influence of CYP2D6 polymorphisms on the efficacy and tolerability of metoprolol tartrate. Two hundred and eighty-one participants with uncomplicated hypertension received 50 mg of metoprolol twice daily followed by response-guided titration to 100 mg twice daily. Phenotypes were assigned based on results of CYP2D6 genotyping and copy number variation assays. Clinical response to metoprolol and adverse effect rates were analyzed in relation to CYP2D6 phenotypes using appropriate statistical tests. Heart rate response differed significantly by CYP2D6 phenotype (P < 0.0001), with poor and intermediate metabolizers showing greater reduction. However, blood pressure response and adverse effect rates were not significantly different by CYP2D6 phenotype. Other than a significant difference in heart rate response, CYP2D6 polymorphisms were not determinants of variability in metoprolol response or tolerability.

Personalized medicine: importance of clinical interpretative skills for real-world patient care

Sequencing of the human genome led to great hopes and expectations for a 'genomics revolution' where disease diagnosis as well as therapies would be based on an individual's genetic makeup. Although significant progress has been made, a number of challenging hurdles must be overcome prior to the broader adoption and implementation of pharmacogenomics and personalized medicine as a part of standard patient care. One aspect of pharmacogenomics-based personalized medicine that has not garnered as much attention, a key focus of this perspective, is the importance of interpreting pharmacogenomic test results in a patient-specific clinical context, and expert physicians and other allied health care providers with the requisite expertise in clinical pharmacology and genomics who are able to provide such services.

Risk of emergent bradycardia associated with initiation of immediate- or slow-release metoprolol

OBJECTIVES

To estimate and compare the risk of emergent bradycardia associated with starting immediate-release (IR) and slow-release (SR) formulations of metoprolol.

DESIGN

Retrospective analysis of administrative claims data.

DATA SOURCE

State of California Medicaid program (Medi-Cal) claims database.

PATIENTS

A total of 31,574 adults beginning metoprolol between May 1, 2004, and November 1, 2009, without a pharmacy claim for a β blocker within the previous 6 months of metoprolol initiation; patients with a primary or secondary diagnosis of symptomatic bradycardia, pacemaker, or implantable cardioverter-defibrillator placement before metoprolol initiation were excluded.

MEASUREMENTS AND MAIN RESULTS

The study outcome was the time to first occurrence of emergent bradycardia, measured at an emergency department visit or hospitalization due to diagnosis of symptomatic bradycardia, after metoprolol initiation. We calculated the incidence and compared the risk of emergent bradycardia by using a proportional hazards model that included the metoprolol formulation with adjustment for total daily metoprolol dose and the use of other drugs as time-varying covariates, as well as demographics and comorbidities. Among 31,574 patients starting metoprolol, 18,516 (58.6%) used the IR formulation. The incidence of emergent bradycardia was 19.1/1000 person-years overall but was nearly twice as common in patients using the IR versus the SR formulation (24.1/1000 person-yrs in the IR group versus 12.9/1000 person-yrs in the SR group, unadjusted hazard ratio [HR] 1.81, 95% confidence interval [CI] 1.28-2.56). Adjustment for other drugs also associated with symptomatic bradycardia (cytochrome P450 2D6 inhibitors, class I or III antiarrhythmics, and atrioventricular node-blocking agents), metoprolol dose, and other participant characteristics somewhat attenuated the association (adjusted HR 1.48, 95% CI 1.03-2.13).

CONCLUSION

The risk of emergent bradycardia associated with metoprolol initiation was higher with the IR formulation than the SR formulation, although the absolute risk was low.

Pharmacogenomics and heart failure in congenital heart disease

Congenital heart disease (CHD) constitutes a lifelong challenge in heart failure management. Current therapy is based mainly on physiologic principles extrapolated from the management of left ventricular failure in adult populations with either ischemic or nonischemic cardiomyopathy. However, there is good evidence of genomic variability in the origin and progression of CHD that suggests the need for a individualized approach to treatment. The developing science of pharmacogenomics presents an opportunity for CHD management broadly, and especially in the context of heart failure. There is growing evidence that individualizing drug therapy for these patients might be beneficial, and that prediction of response to therapy might be possible by incorporating genomic data into the treatment algorithm for individual patients.

Unexpectedly high blood concentration of bisoprolol after an incorrect prescription: A case report

An elderly person died of uncontrolled bradycardia in a hospital. The doctor had prescribed 1.35 mg of bisoprolol fumarate orally, but a nurse mistakenly gave the patient 10 mg of the drug 9 hours prior to her death. Bisoprolol was detected in her blood by liquid chromatography-mass spectrometry at a concentration of 176 ng/mL. Even if the patient had chronic heart failure, this concentration is double the expected value. This patient was found to have a mutation within cytochrome P2D6, with thymidine substituted for cytosine at position 100 and cytosine for guanine at position 4180, causing proline to serine and threonine to serine amino acid substitutions. This mutation in the intermediate metabolizer allele reportedly reduces enzyme activity by half. However, in addition to the type of cytochrome P450 allelic variant, the amount of enzyme product influences metabolism of this drug. In this case, the high blood concentration of bisoprolol was only partly attributable to an error in prescription; its concentration was inexplicably high.

Pharmacogenomics of cardiovascular drugs and adverse effects in pediatrics

Individual response to medication is highly variable. For many drugs, a substantial proportion of patients show suboptimal response at standard doses, whereas others experience adverse drug reactions (ADRs). Pharmacogenomics aims to identify genetic factors underlying this variability in drug response, providing solutions to improve drug efficacy and safety. We review recent advances in pharmacogenomics of cardiovascular drugs and cardiovascular ADRs, including warfarin, clopidogrel, β-blockers, renin-angiotensin-aldosterone system inhibitors, drug-induced long QT syndrome, and anthracycline-induced cardiotoxicity. We particularly focus on the applicability of pharmacogenomic findings to pediatric patients in whom developmental changes in body size and organ function may affect drug pharmacokinetics and pharmacodynamics. Solid evidence supports the importance of gene variants in CYP2C9 and VKORC1 for warfarin dosing and in CYP2C19 for clopidogrel response in adult patients. For the other cardiovascular drugs or cardiovascular ADRs, further studies are needed to replicate or clarify genetic associations before considering uptake of pharmacogenetic testing in clinical practice. With the exception of warfarin and anthracycline-induced cardiotoxicity, there is lack of pharmacogenomic studies on cardiovascular drug response or ADRs aimed specifically at children or adolescents. The first pediatric warfarin pharmacogenomic study indeed indicates differences from adults, pointing out the importance and need for pediatric-focused pharmacogenomic studies.

Genetic variation, β-blockers, and perioperative myocardial infarction

Perioperative myocardial infarction is a common and potentially fatal complication after noncardiac surgery, particular among patients with cardiovascular risk factors. β-blockers have been considered a mainstay in prevention and treatment of perioperative myocardial infarction, yet recent evidence suggests that β-blockers may have an unfavorable risk profile in this setting, and the use has become controversial. What seems conspicuously absent from the current discussion is the appreciation of how much interindividual genetic variation influences the clinical response to β-blocker therapy. Genetic variation in the adrenergic signaling pathway is common, and has a major impact on adrenergic receptor function and β-blocker efficacy in other cardiovascular diseases, such as heart failure and hypertension. Genetic variation in the cytochrome P450 2D6, or CYP2D6, enzyme, which is responsible for the metabolism of most β-blockers, is also important and can lead to poor metabolizing of β-blockers (potential toxicity) or their ultra-rapid degradation (decreased efficacy). Here, we review the molecular, cellular, and physiologic consequences of polymorphisms in the adrenergic signaling pathway and CYP2D6 gene, and show that these are likely relevant factors influencing efficacy, safety, and toxicity of β-blocker therapy in prevention and treatment of perioperative myocardial infarction.

The role of β-blockers in the management of hypertension: an Asian perspective

Following publication of the National Institute of Clinical Excellence (NICE) Guidelines in 2006, the use of β-blockers as first-line therapy in hypertension has been somewhat controversial. However, a recent reappraisal of the European Society of Hypertension guidelines highlights that these agents exhibit similar BP lowering efficacy to other classes of agents, prompting a re-examination of the utility of these agents in various patient populations. The authors felt that it is important to address this controversy and provide an Asian perspective on the place of β-blockers in current clinical practice and the benefits of β-blockade in selected patient populations. In addition to their use as a potential first-line therapy in uncomplicated hypertension, β-blockers have a particular role in patients with hypertension and comorbidities such as heart failure or coronary artery disease, including those who had a myocardial infarction. One advantage which β-blockers offer is the additional protective effects in patients with prior cardiovascular events. Some of the disadvantages attributed to β-blockers appear more related to the older drugs in this class and further appraisal of the efficacy and safety profile of newer β-blockers will lend support to the current guideline recommendations in Asian countries and encourage increased appropriate use of β-blockade in current clinical practice within Asia.

Safety of perioperative β-blocker use: how do β-blockers compare in terms of side effects?

INTRODUCTION

In the perioperative setting, there is still a high incidence of adverse cardiac events due to sudden coronary plaque rupture or oxygen supply-demand imbalance. β-Blockers play an important role in preventing these cardiac events. Discussion, however, remains on the side effects accompanying this therapy.

AREAS COVERED

The evidence for perioperative use of β-blockers is summarized in this review in terms of risk reduction, perioperative safety and current clinical use. Furthermore, data on pharmacokinetics, pharmacodynamics and pharmacogenetics are presented.

EXPERT OPINION

In perioperative care, β-blockers are recommended and can be given safely when started early in a low dose, titrated to heart rate. In the future, there could be a place for added perioperative short-acting β-blockers to further optimize heart rate control.

Relation of ADRB1, CYP2D6, and UGT1A1 polymorphisms with dose of, and response to, carvedilol or metoprolol therapy in patients with chronic heart failure

The response to beta blockers in patients with heart failure could be associated with the genotype of drug-metabolizing enzymes and/or drug targets. The purpose of the present study was to determine whether specific genetic polymorphisms in ADRB1 (encoding the beta1-adrenergic receptor), CYP2D6, and UGT1A1 correlated with dose of, or response to, metoprolol or carvedilol treatment in patients with heart failure. A cohort of patients with heart failure (n = 93), characterized as responders or nonresponders to metoprolol (n = 19) or carvedilol (n = 74) therapy, was retrospectively identified. Individual genotyping was performed for a panel of polymorphisms in the ADRB1, CYP2D6, and UGT1A1 genes. Univariate and multivariate analyses were performed to compare the genotype to the metoprolol or carvedilol response status and dose. A nonresponse was identified in 10 of 19 patients taking metoprolol and 32 of 74 patients taking carvedilol. None of the polymorphisms in ADRB1, CYP2D6, and UGT1A1 were associated with a response or nonresponse. However, a significant relation between the carvedilol (but not metoprolol) dose and the ADRB1 and CYP2D6 genotype was observed. Patients homozygous for the ADRB1 389Gly variant or who were CYP2D6 poor metabolizers achieved a significantly higher dose of carvedilol (p = 0.01 and p = 0.02, respectively). In conclusion, polymorphisms in ADRB1, CYP2D6, and UGT1A1 were not associated with a response to metoprolol or carvedilol therapy in our cohort of patients with heart failure. The ADRB1 and CYP2D6 genotype, alone and in haplotype, were significantly associated with the dose of carvedilol.

Beta-blocker pharmacogenetics in heart failure

Beta-blockers (metoprolol, bisoprolol, and carvedilol) are a cornerstone of heart failure (HF) treatment. However, it is well recognized that responses to a beta-blocker are variable among patients with HF. Numerous studies now suggest that genetic polymorphisms may contribute to variability in responses to a beta-blocker, including left ventricular ejection fraction improvement, survival, and hospitalization due to HF exacerbation. This review summarizes the pharmacogenetic data for beta-blockers in patients with HF and discusses the potential implications of beta-blocker pharmacogenetics for HF patients.

Pharmacogenetics of beta-blockers

Beta-blockers are an important cardiovascular drug class, recommended as first-line treatment of numerous diseases such as heart failure, hypertension, and angina, as well as treatment after myocardial infarction. However, responses to a beta-blocker are variable among patients. Results of numerous studies now suggest that genetic polymorphisms may contribute to variability in responses to beta-blockers. This review summarizes the pharmacogenetic data for beta-blockers in patients with various diseases and discusses the potential implications of beta-blocker pharmacogenetics in clinical practice.

Multiple regression analysis of pharmacogenetic variability of carvedilol disposition in 54 healthy Japanese volunteers

The aim of this study was to evaluate the pharmacogenetic variability in the disposition of carvedilol in the Japanese population. Five or 10 mg of carvedilol was orally administered to 54 healthy Japanese subjects (22-44 years old), and blood samples were taken at 2 and 6 h after dosing. We determined the polymorphic alleles of CYP2D6, CYP2C9, CYP2C19, CYP3A5, UGT2B7, and MDR1 in each subject. The whole blood concentration of R- and S-carvedilol was measured by an HPLC method. The pharmacokinetic parameters in individual subjects were estimated by the Bayesian method using the nonlinear mixed effects model (NONMEM) program. We then examined the effect of the genetic polymorphisms on the variability in the pharmacokinetics of carvedilol using a multiple regression analysis. The oral clearance (CL/F) and also apparent volume of distribution (V/F) of both enantiomers were significantly lower in the subjects with the CYP2D6*10 allele than those with the CYP2D6*1/*1, *1/*2, or *2/*2 genotype, confirming our previous finding that the bioavailability (F) and systemic clearance (CL) of R- and S-carvedilol in the liver is significantly altered in Japanese with the CYP2D6*10 allele. On the other hand, CYP2C9*3, CYP2C19*2, CYP2C19*3, CYP3A5*3, UGT2B7*2, and MDR1 C3435T did not significantly affect the pharmacokinetics of carvedilol in Japanese subjects.

Pharmacokinetics and Pharmacodynamics of Bisoprolol in Rats with Bilateral Ureter Ligation-induced Renal Failure

The effect of renal failure on the pharmacokinetics and pharmacodynamics of bisoprolol was investigated in bilateral ureter-ligated (BUL) rats. The blood bisoprolol concentrations following 30-min intravenous infusion at a rate of 60 microg/kg/min were higher in renal artery-occluded (RAO) rats than in control rats, and were higher in BUL rats than in RAO rats. Increased blood bisoprolol concentrations accompanied decreased mean systemic clearances: 50.7, 36.4, and 26.2 mL/min/kg in control, RAO, and BUL rats, respectively. The finding indicated that approximately 30% of administered bisoprolol was excreted via the kidney, and that not only the renal clearance but also non-renal clearance of bisoprolol was decreased in BUL rats. The beta-blocking action of bisoprolol was assessed by the reduction in isoproterenol-induced increases in the heart rate. The relationship between blood concentration and the beta-blocking action of bisoprolol in BUL rats was similar to that in control rats. These results suggested that renal excretion and hepatic metabolism of bisoprolol were significantly reduced in BUL rats, but that pharmacodynamics of bisoprolol was not altered by acute renal failure.