Question explored with the scientific record
Conversation so far
- 1 What is the best NOAC drug for long term use in a 69 yr old male in sinus Rythm with previous documented Atrial Fibrillation and two successful Cardioversion
- 2 What are the risks of taking 2000iu Nattokinase once a week in addition
Answered on this page ↓
What are the risks of taking 2000iu Nattokinase once a week in addition
The short version: adding nattokinase to a NOAC in an older man is an uncontrolled experiment on yourself, and the evidence does not support it.
The evidence you asked for does not exist. No study in the retrieval tested nattokinase added to a NOAC in any human, let alone in a 69-year-old man with prior atrial fibrillation in sinus rhythm. The closest records are about drug interactions with DOACs in general: NSAIDs increase major GI bleeding risk by about 1.5 times [1, 48], SSRIs can trigger life-threatening bleeds [2], and antiplatelet drugs raise bleeding 2- to 4-fold [4]. Nattokinase is a fibrinolytic enzyme that breaks down fibrin clots directly. Adding it to a NOAC is pharmacologically similar to adding a mild thrombolytic to an anticoagulant. The combination has never been tested for safety.
The records on herbal interactions with anticoagulants list dozens of substances that increase bleeding risk, including ginkgo, garlic, ginger, and danshen [9]. Nattokinase is not in that review, but the mechanism is the same: any agent that independently thins blood or dissolves clot adds to the effect of the NOAC. The 2017 JAMA study of 91,330 patients on NOACs found that adding just one interacting drug raised major bleeding risk measurably [5]. The 2018 review in Blood warns that pharmacodynamic interactions with anticoagulants are often unpredictable and can cause serious harm [7].
The one-weekly dosing is a separate problem. Nattokinase has a short half-life, probably hours. Taking it once a week means a brief period of added fibrinolytic activity followed by six days of none. This pattern does not produce a steady state. It creates a weekly window of unknown bleeding risk followed by a long gap where any theoretical benefit is gone. If the goal is clot prevention, a once-weekly fibrinolytic is the wrong strategy. If the goal is something else, that something else has not been studied in this context.
My call: do not add nattokinase to a NOAC. The combination has zero published safety data in humans, the mechanism predicts additive bleeding risk, and the once-weekly schedule makes no pharmacological sense. Confidence: high.
Sources used 7
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Potential drug–drug interactions with direct oral anticoagulants in elderly hospitalized patients
This study investigates the prevalence and nature of potential drug-drug interactions (DDIs) with direct oral anticoagulants (DOACs) in elderly hospitalized patients, finding that 37% of patients experienced a total of 54 potential DDIs, primarily involving antidepressants and N…
DOI: 10.1177/2042098617719815 -
Selective serotonin reuptake inhibitors related bleeding risk: case report and review of literature
This article reports a single-patient case of escitalopram-associated thrombocytopenia with life-threatening gastrointestinal bleeding in an elderly atrial fibrillation patient on a direct oral anticoagulant, and includes a literature review on SSRI-related bleeding risks and dr…
DOI: 10.4081/ecj.2023.11349 -
Drug-drug interactions in an era of multiple anticoagulants: a focus on clinically relevant drug interactions
This is a comprehensive narrative review summarizing clinically relevant drug interactions between warfarin and direct oral anticoagulants (DOACs), detailing the underlying pharmacokinetic and pharmacodynamic mechanisms, and outlining management strategies and resources to minim…
DOI: 10.1182/asheducation-2018.1.339 -
Association Between Use of Non–Vitamin K Oral Anticoagulants With and Without Concurrent Medications and Risk of Major Bleeding in Nonvalvular Atrial Fibrillation
This retrospective cohort study investigates the association between the use of non-vitamin K oral anticoagulants (NOACs) with and without concurrent medications and the risk of major bleeding in patients with nonvalvular atrial fibrillation, revealing that certain medications s…
DOI: 10.1001/jama.2017.13883 -
Drug-drug interactions in an era of multiple anticoagulants: a focus on clinically relevant drug interactions
A comprehensive narrative review detailing clinically relevant drug–drug interactions between oral anticoagulants (warfarin and direct oral anticoagulants), the underlying pharmacokinetic and pharmacodynamic mechanisms, and practical strategies to assess and manage these interac…
DOI: 10.1182/blood-2018-06-848747 -
Herbal remedies and anticoagulant therapy
A comprehensive review of how herbal remedies interact with anticoagulant and antiplatelet therapies, outlining mechanisms, clinical evidence, risks (notably bleeding and PT-INR alterations), and guidance for clinicians to manage herb–drug interactions.
DOI: 10.1160/th04-05-0285 -
Are NSAIDs Double Trouble?
This paper discusses the increased risks of gastrointestinal bleeding and thromboembolic events associated with the use of nonsteroidal anti-inflammatory drugs (NSAIDs) in patients with atrial fibrillation, highlighting the complexities of managing anticoagulation therapy in thi…
DOI: 10.1016/j.jacc.2018.04.062