Insights into the Pharmacokinetics and Pharmacodynamics of Direct Oral Anticoagulants in Older Adults with Atrial Fibrillation: A Structured Narrative Review

Oral anticoagulant therapy in older adults

Patients aged ≥65 years not only account for the majority of patients with atrial fibrillation (AF) and venous thromboembolism (VTE), they are also at a higher risk of morbidity, mortality, and undertreatment than younger patients. Several age-related physiological changes with effects on drug pharmacokinetics/-dynamics and blood vessel fragility as well as the higher prevalence of geriatric conditions such as frailty, multimorbidity, polypharmacy, fall risk, dementia, and malnutrition make older persons more vulnerable to disease- and anticoagulation-related complications. Moreover, because older patients with AF/VTE are underrepresented in oral anticoagulation (OAC) trials, evidence on OAC in older adults with AF/VTE is mainly based on subgroup analyses from clinical trials and observational studies. A growing body of such limited evidence suggests that direct oral anticoagulants (DOACs) may be superior in terms of efficacy and safety compared to vitamin K antagonists in older persons with AF/VTE and that specific DOACs may have a differing risk-benefit profile. In this narrative review, we summarize the evidence on epidemiology of AF/VTE, impact of age-related physiological changes, efficacy/safety of OAC, specifically considering individuals with common geriatric conditions, and review OAC guideline recommendations for older adults with AF/VTE. We also propose a research agenda to improve the evidence basis on OAC older individuals with AF/VTE, including the conduct of advanced age-specific and pragmatic studies using less restrictive eligibility criteria and patient-reported health outcomes, in order to compare the effectiveness and safety of different DOACs, and investigate lower-dose regimens and optimal OAC durations in older patients.

Idarucizumab in dabigatran-treated patients with acute stroke: a review and clinical update

Idarucizumab is an antibody fragment specific for the immediate reversal of dabigatran anticoagulation effects. The use of idarucizumab is approved for dabigatran-treated patients suffering from life-threatening or uncontrolled bleeding and those in need of urgent surgery or invasive procedures. Data from randomized controlled clinical trials and real-world experience provide reassuring evidence about the efficacy and safety of idarucizmab use in patients with acute stroke. In this narrative review, we summarize the available real-world evidence and discuss the relevance and importance of idarucizumab treatment in acute stroke patients in everyday clinical practice. In addition, we also discuss special issues like prothrombin complex concentrate application as an alternative to idarucizumab, its application before endovascular therapy, sensitivity of thrombi to lysis, and necessary laboratory examinations.

[Drug therapy for arterial hypertension and atrial fibrillation in frail patients : Are there any new insights and recommendations?]

The frail and elderly are considered to be at particular risk of suffering an adverse drug reaction. Empirical studies confirm the increased rate of adverse drug reactions. Whether frailty per se impairs drug metabolism or the underlying organ ageing processes and multimorbidity cannot be answered with certainty based on current data. Cardiovascular diseases exhibit a considerable interdependence with frailty. For example, there is a disproportionate syndromal interdependence between heart failure and frailty, and the typical ageing processes of the sinus node can be interpreted as heartbeat frailty. Multimorbidity in the elderly often includes a cluster of chronic cardiovascular diseases, often leading to the use of several cardiovascular medications as required. More recent definitions of polypharmacy assess the appropriateness of drugs rather than their number. The Fit-fOR-The-Aged (FORTA) list, the PRISCUS 2.0 list and the "Cochrane Library Special Collection on deprescribing", for example, offer a practice-oriented assessment aid. In the treatment of arterial hypertension, the target values for older people have also been set ever lower in recent years. In the case of frail elderly people, on the other hand, the guidelines do not specify a strict blood pressure target corridor; tolerability is the crucial factor here. When initiating antihypertensive therapy in frail individuals, one can consider monotherapy-in a departure from the standard case of dual combination therapy. The OPTIMISE study showed that discontinuation of one blood pressure medication did not lead to better tolerability of the drug therapy. Current studies come to differing conclusions regarding the risk-benefit assessment of new oral anticoagulants compared to vitamin K antagonists in the anticoagulation of frail elderly people with atrial fibrillation. Shared decision-making, which could improve adherence particularly in older people, is recommended.

Thrombotic events associated with low baseline direct oral anticoagulant levels in atrial fibrillation: the MAS study

ABSTRACT

Although effective and safe, treatment with direct oral anticoagulants (DOAC) in atrial fibrillation (AF) is still associated with thrombotic complications. Whether the measurement of DOAC levels may improve treatment efficacy is an open issue. We carried out the observational, prospective, multicenter Measure and See (MAS) study. Blood was collected 15 to 30 days after starting DOAC treatment in patients with AF who were followed-up for 1 year. Plasma samples were centralized for DOAC level measurement. Patients' DOAC levels were converted into drug/dosage standardized values to allow a pooled analysis in a time-dependent, competitive-risk model. The measured values were transformed into standardized values (representing the distance of each value from the overall mean) by subtracting the DOAC-specific mean value from the original values and dividing by the standard deviation. Trough and peak DOAC levels were assessed in 1657 and 1303 patients, respectively. In total, 21 thrombotic complications were recorded during 1606 years of follow-up (incidence of 1.31% of patients per year). Of 21 thrombotic events, 17 occurred in patients whose standardized activity levels were below the mean of each DOAC (0); the incidence was the highest (4.82% of patients per year) in patients whose standardized values were in the lowest class (-1.00 or less). Early measurement of DOAC levels in patients with AF allowed us to identify most of the patients who, having low baseline DOAC levels, subsequently developed thrombotic complications. Further studies are warranted to assess whether thrombotic complications may be reduced by measuring baseline DOAC levels and modifying treatment when indicated. This trial was registered at www.ClinicalTrials.gov as #NCT03803579.

Anticoagulant drugs for patients with atrial fibrillation on dialysis: a systematic analysis and network meta-analysis

Objective: A lack of clarity persists regarding the efficacy and risks associated with direct oral anticoagulants (DOACs) in end-stage renal disease (ESRD) patients with atrial fibrillation (AF) undergoing dialysis, primarily due to limited retrospective studies. Therefore, the objective of this study was to evaluate the existing data and propose a practical protocol for the clinical utilization of DOACs in ESRD patients with AF undergoing dialysis. Methods: PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials were searched for clinical studies evaluating DOACs in ESRD patients with AF on dialysis published up to 2 February 2023. DOACs included warfarin, dabigatran, apixaban, edoxaban, and rivaroxaban. The outcomes were mortality, ischemic stroke, hemorrhagic stroke, any stroke, gastrointestinal bleeding, major bleeding, intracranial bleeding, and minor bleeding. Results: Compared with placebo, apixaban (HR = 0.97, 95% CI: 0.88-1.07), rivaroxaban (HR = 0.91, 95% CI: 0.76-1.10), and warfarin (HR = 0.96, 95% CI: 0.90-1.01) did not reduce mortality. Regarding direct comparisons of mortality, the comparisons of warfarin vs. apixaban (HR = 0.99, 95% CI: 0.92-1.06), placebo vs. warfarin (HR = 1.04, 95% CI: 0.99-1.11), and rivaroxaban vs. warfarin (HR = 0.96, 95% CI: 0.80-1.14) did not significantly reduce mortality. Based on the surface under the cumulative ranking curve, rivaroxaban (75.53%), warfarin (62.14%), and apixaban (45.6%) were the most effective interventions for managing mortality, and placebo (16.74%) was the worst. Conclusion: In conclusion, rivaroxaban demonstrated efficacy in reducing mortality and the incidence of ischemic stroke, gastrointestinal bleeding, and intracranial hemorrhage. Dabigatran is recommended for the prevention of hemorrhagic stroke. However, caution should be exercised due to the risk of major bleeding. Warfarin can effectively reduce minor bleeding but does not offer significant protection against gastrointestinal or intracranial bleeding. Apixaban was not recommended for mortality reduction or for preventing ischemic or hemorrhagic strokes. Further research will be necessary to establish specific clinical protocols.

Use of direct oral anticoagulants for venous thromboembolism treatment at extremes of body weight, renal and liver function: an illustrated review

Direct oral anticoagulants (DOACs) have been a welcome addition to clinical practice due to the practical advantages they confer over traditional anticoagulants. In many countries, DOACs are now used as first-line treatment for the management of venous thromboembolism (VTE). Traditional anticoagulants allow for a degree of individualization, either through monitoring the international normalized ratio in the case of vitamin-K antagonists or through dose titration according to bodyweight in the case of low-molecular-weight heparin. However, the use of fixed doses and removal of the need for routine monitoring has created uncertainty in prescribing DOACs for patients at the extremes of bodyweight, renal function, and patients with liver impairment, who were not well represented in the DOAC licensing clinical trials. The discipline of pharmacokinetics is concerned with the movement of drugs through the body. Although the extremes of bodyweight and renal and liver function will influence the pharmacokinetics of DOACs, are these changes significant enough to affect clinical outcomes of bleeding and thrombosis? In other words, can the fixed-dosing strategy of DOACs accommodate these differences in physiology? In this review, we recap key pharmacokinetic principles for drug dosing; review venous thromboembolism trial and real-world data on patients prescribed DOACs at the extremes of bodyweight, renal function, and liver function; relate this to the pharmacokinetic properties of DOACs; and summarize the state of the field and current unknowns.