The Perils of Combination Antithrombotic Therapy and Potential Resolutions

Current update on herbal sources of antithrombotic activity—a comprehensive review

Background

Herbs are commonly used to treat cardiovascular diseases in various traditional medicine. On the other hand, herb-drug interactions are most commonly encountered with conventional antiplatelet and anticoagulant drug prescriptions. This review presents a compilation of plants investigated for antiplatelet and anticoagulation recently and enumerates their possible lead compounds responsible for its action for paving further drug discovery and knowledge update.

Main body of the abstract

Information about the herbs was withdrawn from the PubMed database of the previous 5 years. We also hand-searched the bibliography of relevant articles for the acquisition of additional information. About 72 herbal sources were identified with the effect of antiplatelet activity, antithrombotic activity, and anticoagulant activity. Bioactive compounds and various secondary metabolites responsible for it, such as alkaloids, saponins, flavonoids, coumarins, polyphenols, furan derivatives, iridoid glycosides, sesquiterpenes, aporphine compounds, were reported.

Conclusion

Newer pharmacological moieties are needed to prevent or reduce the adverse effects of current anti-thrombotic agents and to improve the safety of patients and cost-effectiveness.

Structure-activity relationship studies for multitarget antithrombotic drugs

Thrombosis is a complex process involving multiple pathways. Currently, therapy relies on the combination of two or more antithrombotic drugs, showing that inhibiting more than one target provides benefits in the prevention and treatment of thrombosis. This review focuses on structure-activity relationship studies of molecules possessing multiple actions against thrombosis, namely, dual inhibitors of coagulation, dual inhibitors of coagulation and platelet aggregation, and also dual inhibitors of platelet aggregation. EP217609 has just entered clinical trials, which raise the expectations on the multitarget strategy to prevent or treat thrombosis.

Guidelines for the prevention of stroke in patients with stroke and transient ischemic attack: a guideline for healthcare professionals from the American Heart Association/American Stroke Association

The aim of this updated guideline is to provide comprehensive and timely evidence-based recommendations on the prevention of future stroke among survivors of ischemic stroke or transient ischemic attack. The guideline is addressed to all clinicians who manage secondary prevention for these patients. Evidence-based recommendations are provided for control of risk factors, intervention for vascular obstruction, antithrombotic therapy for cardioembolism, and antiplatelet therapy for noncardioembolic stroke. Recommendations are also provided for the prevention of recurrent stroke in a variety of specific circumstances, including aortic arch atherosclerosis, arterial dissection, patent foramen ovale, hyperhomocysteinemia, hypercoagulable states, antiphospholipid antibody syndrome, sickle cell disease, cerebral venous sinus thrombosis, and pregnancy. Special sections address use of antithrombotic and anticoagulation therapy after an intracranial hemorrhage and implementation of guidelines.

Practical use of dabigatran etexilate for stroke prevention in atrial fibrillation

Atrial fibrillation (AF) is associated with an increased risk of thromboembolism, and is the most prevalent factor for cardioembolic stroke. Vitamin K antagonists (VKAs) have been the standard of care for stroke prevention in patients with AF since the early 1990s. They are very effective for the prevention of cardioembolic stroke, but are limited by factors such as drug-drug interactions, food interactions, slow onset and offset of action, haemorrhage and need for routine anticoagulation monitoring to maintain a therapeutic international normalised ratio (INR). Multiple new oral anticoagulants have been developed as potential replacements for VKAs for stroke prevention in AF. Most are small synthetic molecules that target thrombin (e.g. dabigatran etexilate) or factor Xa (e.g. rivaroxaban, apixaban, edoxaban, betrixaban, YM150). These drugs have predictable pharmacokinetics that allow fixed dosing without routine laboratory monitoring. Dabigatran etexilate, the first of these new oral anticoagulants to be approved by the United States Food and Drug Administration and the European Medicines Agency for stroke prevention in patients with non-valvular AF, represents an effective and safe alternative to VKAs. Under the auspices of the Regional Anticoagulation Working Group, a multidisciplinary group of experts in thrombosis and haemostasis from Central and Eastern Europe, an expert panel with expertise in AF convened to discuss practical, clinically important issues related to the long-term use of dabigatran for stroke prevention in non-valvular AF. The practical information reviewed in this article will help clinicians make appropriate use of this new therapeutic option in daily clinical practice.

Ischemic stroke in patients receiving aspirin

BACKGROUND

The widespread use of aspirin-driven vascular prevention strategies does not impede the occurrence of first and recurrent ischemic strokes in numerous subjects. It is not clear what factors are associated with aspirin failure beyond the functional diagnosis of aspirin resistance in selected subjects. Current management guidelines provide little or no recommendations on the proper strategy for subjects who had a stroke while receiving aspirin. We assessed clinical features of subjects who had a first or recurrent stroke while taking aspirin.

METHODS

We studied demographic characteristics, vascular risk factors, stroke subtypes, and concomitant medication use in subjects with first or recurrent ischemic strokes. Patients receiving antiplatelet medications other than aspirin and/or oral anticoagulants were excluded from this analysis.

RESULTS

Seven hundred and nine patients with first (n = 552) or recurrent (n = 157) ischemic stroke were evaluated. Aspirin was being taken by 29% of first and 48% of recurrent stroke subjects. There was a higher prevalence of hypertension, hypercholesterolemia, and smoking in aspirin users with first and recurrent stroke (P < .05). Diabetes and coronary artery disease were more frequent in aspirin users with first ischemic strokes (P < .003), but not in those who had recurrent ischemic strokes. Aspirin users were more likely to be also receiving statins and antihypertensive drugs (P < .001).

CONCLUSIONS

Aspirin failure in ischemic stroke prevention may exceed functional resistance to aspirin and could be associated with a higher prevalence of lacunar stroke, comorbidities, and/or adverse interactions with other drugs. These patients may require a different approach regarding prevention strategies.