Association of CYP2D6 and ADRB1 genes with hypotensive and antichronotropic action of betaxolol in patients with arterial hypertension

Multi-Ethnic Analysis of Cardiac Pharmacogenetic Markers of Cytochrome P450 and Membrane Transporters Genes in the Russian Population

Aim. To summarize Russian studies using pharmacogenetic testing as applied to cardiology.Material and methods. The authors conducted an online search for articles in December 2018 using the following databases: PubMed, Google Scholar, eLIBRARY. The search was carried out by keywords: "Russia", "Russian", "cardiology" together with the terms associated with the polymorphic marker, including: «P450», «CYP2C19», «CYP2D6», «CYP2B1», «CYP2B6», «CYP2Е1», «CYP2C8», «CYP2C9», «CYP3A4», «CYP3A5», «CYP1A1», «CYP1A2», «CYP4F2», «CYP4F1», «ABCB1», «SLCO1B1», «VKORC1», «GGCX», «SULT1A1», «CULT1», «CES1», «gene», «genes», «pharmacogenetics», «pharmacogenomics», «ethnic group».Results. Generalization of information allowed to identify obscure genes that need to be investigated in pharmacogenetic studies. This information can be used for the development of dosing algorithms and the priority choice of drugs, considering the results of pharmacogenetic testing and planning future research.Conclusion. The results of the literature review indicate the importance of studying the most clinically valid and clinically useful pharmacogenetic markers (CYP2C19, CYP2C9, VKORC1, SLCO1B1) among various ethnic groups in the Russian Federation. With the accumulation of evidence of clinical validity and clinical utility of other pharmacogenetic markers (CES1, CYP2D6*4, etc.), the problem of interethnic differences in the carriage of clinically significant polymorphisms of these genes identified in previous studies in the Russian Federation increasingly requires attention. The most promising for the introduction into the clinical practice in the Russian Federation in the near future are polymorphic markers of the CYP2C19, CYP2C9, VKORC1 and SLCO1B1 genes.

ADME pharmacogenetics: future outlook for Russia

This systematic review reflects the results of pharmacogenetic studies in the Russian Federation aimed at studying the genes involved in the drug biotransformation system. The works of Russian researchers found by us are mostly devoted to microsomal liver oxidation enzymes (metabolism) and membrane transporter systems (absorption and excretion). This review presents population-ethnic and associative clinical studies on the genes of the CYP450 system, noncytochrome oxidation enzymes ( SULT1A1, CES1), membrane transporter system genes ( ABCB1, SLCO1B1) and warfarin biotransformation enzymes ( VKORC1, GGCX). The information is structured in the form of 11 tables, divided by regions of the Russian Federation.

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.

[Pharmacokinetic risk factors of beta-blockers overdose in the elderly: Case report and pharmacology approach]

Beta-blockers are widely prescribed in elderly patients and may induce severe adverse drug reactions. We report a case of bisoprolol-induced bradycardia in an elderly patient with impaired renal function and use of cytochrome P450 inhibitors. A literature review has been performed in order to analyze pharmacokinetic risk factors of beta-blockers overdosing in geriatrics. Various mechanisms can result in decreased elimination of beta-blockers. These mechanisms vary according to the beta-blocker agent and may be combined in some individuals, especially elderly patients. This can lead to unexpected overexposure. Knowledge about drug interactions and pharmacokinetic elimination pathways is important for preventing overexposure and adverse drug reactions when using beta-blockers.

Age-dependent sympathetic neural responses to ß1 selective beta-blockade in untreated hypertension-related tachycardia

BACKGROUND

Elevated heart rate (HR) increases cardiovascular morbidity and mortality in hypertension. The impact of beta-blockers on patient prognosis in hypertension is controversial. This study examined the age-related effects of betaxolol on HR, muscle sympathetic nerve activity (MSNA), blood pressure (BP) and sympathovagal balance in untreated males with hypertension and tachycardia.

METHODS

Ten young (age 26 ± 1 years) and seven older (age 50 ± 4 years) males underwent measurement of BP, HR, HR variability (Poincare plot) and MSNA before and after 8 weeks treatment with betaxolol at the initial starting dose of 10 mg/day, which was increased to 20 mg/day once daily after 4 weeks in all subjects.

RESULTS

In younger subjects, betaxolol decreased systolic BP (-13 ± 4 mm Hg, p = .01) and HR (-29 ± 4 bpm, p < .001) but not MSNA (3 ± 3 burst/min., p = 0.47) after 8 weeks. In older subjects a pronounced reduction in BP (-27 ± 7, p = .007) was accompanied by a significant decrease in MSNA (-13 ± 5 burst/min., p < .05) and HR (-17 ± 4 bpm, p = .002). SD1/SD2 ratio of Poincare plot increased in younger (0.36 ± 0.03 vs 0.51 ± 0.05, p = .004), but not in older (0.43 ± 0.08 vs 0.54 ± 0.12, p = .50) subjects.

CONCLUSION

Autonomic neural responses to betaxolol are age-dependent in hypertension-related tachycardia. Betaxolol reduces sympathetic drive to the heart, but not to the peripheral vessels confirming the contribution of augmented cardiac sympathetic activity to disease pathophysiology in younger adults. In older hypertensives, the sympathovagal balance is not influenced by betaxolol. The paradoxical reduction in MSNA despite lowering of BP and HR in older patients may suggest age-related functional decrements in autonomic control and/or inhibitory effects of betaxolol on the central nervous system.

Dosing Recommendations for Concomitant Medications During 3D Anti-HCV Therapy

The development of direct-acting antiviral (DAA) agents has reinvigorated the treatment of hepatitis C virus infection. The availability of multiple DAA agents and drug combinations has enabled the transition to interferon-free therapy that is applicable to a broad range of patients. However, these DAA combinations are not without drug-drug interactions (DDIs). As every possible DDI permutation cannot be evaluated in a clinical study, guidance is needed for healthcare providers to avoid or minimize drug interaction risk. In this review, we evaluated the DDI potential of the novel three-DAA combination of ombitasvir, paritaprevir, ritonavir, and dasabuvir (the 3D regimen) with more than 200 drugs representing 19 therapeutic drug classes. Outcomes of these DDI studies were compared with the metabolism and elimination routes of prospective concomitant medications to develop mechanism-based and drug-specific guidance on interaction potential. This analysis revealed that the 3D regimen is compatible with many of the drugs that are commonly prescribed to patients with hepatitis C virus infection. Where interaction is possible, risk can be mitigated by paying careful attention to concomitant medications, adjusting drug dosage as needed, and monitoring patient response and/or clinical parameters.

Associations between ADRB1 and CYP2D6 gene polymorphisms and the response to β-blocker therapy in hypertension

OBJECTIVE

To investigate the associations between β1-adrenergic receptor (ADRB1) and cytochrome P450 2D6 (CYP2D6) gene polymorphisms and β-blocker treatment outcomes in patients with hypertension.

METHODS

Chinese patients with essential hypertension were treated with the β-blocker metoprolol and followed up for 12 weeks. xTAG® liquid-chip technology was used for CYP2D6 100 C > T and ADRB1 1165G > C genotyping. Associations between gene polymorphisms and antihypertensive therapy outcomes were assessed by generalized linear model fitting. A decrease of ≥ 10 mmHg in systolic blood pressure indicated an effective treatment outcome.

RESULTS

A total of 93 patients were included in the study. Mutant allele frequencies of 61.29% and 58.60% were obtained for ADRB1 and CYP2D6, respectively. There was no significant interaction between the effects of ADRB1 and CYP2D6 gene polymorphisms on treatment outcome. Patients homozygous for the mutant ADRB1 genotype (CC) had better treatment outcomes than those heterozygous for the mutation (GC). Interestingly, β-blocker treatment duration was an independent factor associated with treatment outcome.

CONCLUSIONS

The ADRB1 1165G > C gene polymorphism and β-blocker treatment duration are independent factors associated with β-blocker treatment outcome. These findings suggest that the selection of antihypertensive therapy should take into consideration the patient's genotype.

Predictivity of dog co-culture model, primary human hepatocytes and HepG2 cells for the detection of hepatotoxic drugs in humans

Drug induced liver injury (DILI) is a major cause of attrition during early and late stage drug development. Consequently, there is a need to develop better in vitro primary hepatocyte models from different species for predicting hepatotoxicity in both animals and humans early in drug development. Dog is often chosen as the non-rodent species for toxicology studies. Unfortunately, dog in vitro models allowing long term cultures are not available. The objective of the present manuscript is to describe the development of a co-culture dog model for predicting hepatotoxic drugs in humans and to compare the predictivity of the canine model along with primary human hepatocytes and HepG2 cells. After rigorous optimization, the dog co-culture model displayed metabolic capacities that were maintained up to 2 weeks which indicates that such model could be also used for long term metabolism studies. Most of the human hepatotoxic drugs were detected with a sensitivity of approximately 80% (n=40) for the three cellular models. Nevertheless, the specificity was low approximately 40% for the HepG2 cells and hepatocytes compared to 72.7% for the canine model (n=11). Furthermore, the dog co-culture model showed a higher superiority for the classification of 5 pairs of close structural analogs with different DILI concerns in comparison to both human cellular models. Finally, the reproducibility of the canine system was also satisfactory with a coefficient of correlation of 75.2% (n=14). Overall, the present manuscript indicates that the dog co-culture model may represent a relevant tool to perform chronic hepatotoxicity and metabolism studies.

Fatal rhabdomyolysis in a patient with liver cirrhosis after switching from simvastatin to fluvastatin

HMG-CoA reductase inhibitors (statins) are widely used to treat hypercholesterolemia. Among the adverse effects associated with these drugs are statin-associated myopathies, ranging from asymptomatic elevation of serum creatine kinase to fatal rhabdomyolysis. Fluvastatin-induced fatal rhabdomyolysis has not been previously reported. We describe here a patient with liver cirrhosis who experienced fluvastatin-induced fatal rhabdomyolysis. This patient had been treated with simvastatin (20 mg/day) for coronary artery disease and was switched to fluvastatin (20 mg/day) 10 days before admission. He was also taking aspirin, betaxolol, candesartan, lactulose, and entecavir. Rhabdomyolysis was complicated and continued to progress. He was treated with massive hydration, urine alkalization, intravenous furosemide, and continuous renal replacement therapy for acute renal failure, but eventually died due to rhabdomyolysis complicated by hepatic failure. In conclusion, fluvastatin should be used with caution in patients with liver cirrhosis, especially with other medications metabolized with CYP2C9.

The human gene map for performance and health-related fitness phenotypes: the 2006-2007 update

This update of the human gene map for physical performance and health-related fitness phenotypes covers the research advances reported in 2006 and 2007. The genes and markers with evidence of association or linkage with a performance or a fitness phenotype in sedentary or active people, in responses to acute exercise, or for training-induced adaptations are positioned on the map of all autosomes and sex chromosomes. Negative studies are reviewed, but a gene or a locus must be supported by at least one positive study before being inserted on the map. A brief discussion on the nature of the evidence and on what to look for in assessing human genetic studies of relevance to fitness and performance is offered in the introduction, followed by a review of all studies published in 2006 and 2007. The findings from these new studies are added to the appropriate tables that are designed to serve as the cumulative summary of all publications with positive genetic associations available to date for a given phenotype and study design. The fitness and performance map now includes 214 autosomal gene entries and quantitative trait loci plus seven others on the X chromosome. Moreover, there are 18 mitochondrial genes that have been shown to influence fitness and performance phenotypes. Thus,the map is growing in complexity. Although the map is exhaustive for currently published accounts of genes and exercise associations and linkages, there are undoubtedly many more gene-exercise interaction effects that have not even been considered thus far. Finally, it should be appreciated that most studies reported to date are based on small sample sizes and cannot therefore provide definitive evidence that DNA sequence variants in a given gene are reliably associated with human variation in fitness and performance traits.