ABSTRACT
Rivaroxaban is a direct-acting oral anticoagulant approved to prevent strokes in patients with atrial fibrillation. Dosage recommendations are approved for all adult patients to receive either 15 mg or 20 mg once daily depending upon renal function. There are a number of reasons to believe rivaroxaban dosing could be more effective and/or safer for more patients if increased dosing precision is available. Because real-world patients are more diverse than those studied in phase III clinical trials, we evaluated the extremes of creatinine clearance (CrCl) on rivaroxaban clearance using a published population pharmacokinetic model and applying exposure variation limits (±20%) based on published literature. The proposed dosing recommendations are 10 mg once daily (CrCl 15-29 ml/min), 15 mg once daily (CrCl 30-69 ml/min), 10 mg twice daily (CrCl 70-159 ml/min), and 15 mg twice daily (CrCl 160-250 ml/min). These new dosing recommendations should be prospectively tested for predictive accuracy and to assess the impact on AF patient efficacy and safety.
Subject(s)
Atrial Fibrillation/drug therapy , Factor Xa Inhibitors/administration & dosage , Rivaroxaban/administration & dosage , Administration, Oral , Aged , Area Under Curve , Computer Simulation , Dose-Response Relationship, Drug , Drug Administration Schedule , Drug Dosage Calculations , Factor Xa Inhibitors/adverse effects , Factor Xa Inhibitors/pharmacokinetics , Humans , Male , Models, Biological , Rivaroxaban/adverse effects , Rivaroxaban/pharmacokineticsABSTRACT
Digoxin improves exercise tolerance and reduces hospitalizations in patients with systolic heart failure, but its use has declined progressively for the past two decades. The Digitalis Investigation Group trial showed that digoxin reduced hospitalizations but had a neutral effect on total mortality. There was evidence that mortality caused by worsening heart failure was less, but there was also a signal suggesting an increase in other cardiac (presumed arrhythmic) death. Use of digoxin has declined substantially and recent guideline recommendations have significantly de-emphasized the importance of this drug in the management of heart failure. Two developments suggest that re-evaluation of the contemporary role of digoxin in the management of heart failure with reduced ejection fraction is warranted. First, heart failure remains progressive, characterized by chronic debility, exercise intolerance, and frequent and costly hospitalizations, despite evidence-based drug and device therapies that prolong survival. Health economics have made reducing hospitalizations in patients with heart failure a major priority. Second, a strong association has emerged between serum concentration and the safety and efficacy of digoxin, which indicates a change in our approach to dosing this agent is needed. Experimental and clinical results suggest that optimizing therapeutic benefit and avoiding harm means dosing to achieve low serum digoxin concentrations (0.5-0.9 ng/mL). Digoxin is an inexpensive agent and the totality of evidence indicates that it reduces hospitalizations and improves symptoms safely when dosed to achieve low serum concentrations. These findings suggest digoxin should have a more prominent therapeutic role in patients with heart failure and reduced ejection fraction.
Subject(s)
Digoxin , Exercise Tolerance/drug effects , Heart Failure, Systolic , Hospitalization , Cardiotonic Agents/administration & dosage , Cardiotonic Agents/adverse effects , Cardiotonic Agents/blood , Cause of Death , Chronic Disease , Digoxin/administration & dosage , Digoxin/adverse effects , Digoxin/blood , Disease Management , Dose-Response Relationship, Drug , Drug Monitoring/methods , Heart Failure, Systolic/drug therapy , Heart Failure, Systolic/mortality , Heart Failure, Systolic/physiopathology , Humans , Mortality , Outcome Assessment, Health Care , Practice Guidelines as Topic , Stroke Volume/drug effectsABSTRACT
OBJECTIVES: The Arg389Gly polymorphism (Arg389Gly) in the beta1-adrenergic receptor gene (ADRB1) has been associated with improvement in left-ventricular remodeling with beta-blocker treatment. One study of risk for heart failure suggested a synergistic effect of ADRB1 Arg389Gly with the insertion/deletion polymorphism in the alpha2C-adrenergic receptor gene (ADRA2C). We tested whether the ADRA2C insertion/deletion polymorphism was associated with beta-blocker response in heart failure, either alone or in combination with the ADRB1Arg389Gly polymorphism. METHODS: Fifty-four beta-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 beta-blocker therapy of heart failure patients.
