Clopidogrel with Bilberry Interaction Details
Brand Names Associated with Clopidogrel
- Clopidogrel
- Plavix®
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Nov 11, 2023
Interaction Effect
Increased risk of bleeding
Interaction Summary
Theoretically, bilberry may potentiate the effects of antiplatelet agents. One case report describes a patient taking several herbal medicines including bilberry (Vaccinium myrtilis (VMA)) who developed substantial postoperative bleeding. Oral doses of VMA (Myrtocyan(R)), inhibited platelet aggregation in humans . VMA inhibited platelet aggregation and prolonged bleeding time in rabbits . VMA increased production of prostaglandin I2-like substances in vascular tissues in rats, leading to enhanced anti-aggregatory mechanisms .
Severity
Moderate
Onset
Delayed
Evidence
Theoretical
How To Manage Interaction
Caution is advised if bilberry is taken with an antiplatelet agent. Monitor the patient closely for signs and symptoms of bleeding.
Mechanism Of Interaction
Additive antiplatelet effects
Literature Reports
A) A 60-year-old female taking several undisclosed dietary supplements up to the day of surgery (left modified radical mastectomy with sentinel node biopsy and right breast reduction) experienced substantial postoperative bleeding. Herbal supplements included bilberry, ginkgo, huang qi (astragalus), and ginseng. Vitamin supplements included vitamin E, vitamin C, and vitamin B12. Prescription medications included montelukast, albuterol, salmeterol, fluticasone, quinine, and sertraline. Preoperative labs were normal except for a slightly prolonged prothrombin time of 15.6 seconds (reference range, 10.2 to 12.3 seconds), and INR 1.27 (normal 1). The patient and surgeons were informed of the possible increased risk of bleeding due to the herbal supplements and agreed to proceed with surgery. No medicines that could affect bleeding were given during surgery. Blood loss during the procedure was estimated at 250 milliliters (mL). In the postanesthesia unit both breasts and axilla were noted to have significant ecchymotic discoloration. Surgical drains collected 269 mL of grossly bloody fluid, Hgb and Hct were 10.1 g/dL and 26% respectively. The patient required emergency exploratory surgery with removal of a hematoma. The authors concluded that the combination of dietary supplements and prescription drugs may have resulted in an acquired coagulation disorder or vitamin K deficiency and increased loss of blood postoperatively in this patient .
B) Platelet aggregation induced by collagen or adenosine diphosphate (ADP) was reduced in patients receiving Myrtocyan(R) (Vaccinium myrtilis (VMA)). Thirty healthy subjects who had not used aspirin, nonsteroidal anti-inflammatory drugs, or corticosteroids received VMA 480 milligrams (mg), ascorbic acid 3 grams, or VMA 480 mg plus ascorbic acid 3 grams, daily in three divided doses. VMA decreased both collagen and ADP-induced platelet aggregation at 30 and 60 days of treatment. Addition of ascorbic acid further enhanced the decrease in platelet aggregation .
Clopidogrel Overview
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Clopidogrel is used alone or with aspirin to prevent serious or life-threatening problems with the heart and blood vessels in people who have had a stroke, heart attack, or severe chest pain. This includes people who have percutaneous coronary intervention (PCI; angioplasty; a type of heart surgery) that may involve inserting coronary stents (metal tubes surgically placed in clogged blood vessels to improve blood flow) or who have coronary artery bypass grafting (CABG; a type of heart surgery). Clopidogrel is also used to prevent serious or life-threatening problems with the heart and blood vessels in people who have peripheral arterial disease (poor circulation in the blood vessels that supply blood to the legs). Clopidogrel is in a class of medications called antiplatelet medications. It works by preventing platelets (a type of blood cell) from collecting and forming clots that may cause a heart attack or stroke.
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Definitions
Severity Categories
Contraindicated
These drugs, generally, should not be used together simultaneously due to the high risk of severe adverse effects. Combining these medications can lead to dangerous health outcomes and should be strictly avoided unless otherwise instructed by your provider.
Major
This interaction could result in very serious and potentially life-threatening consequences. If you are taking this drug combination, it is very important to be under close medical supervision to minimize severe side effects and ensure your safety. It may be necessary to change a medication or dosage to prevent harm.
Moderate
This interaction has the potential to worsen your medical condition or alter the effectiveness of your treatment. It's important that you are monitored closely and you potentially may need to make adjustments in your treatment plan or drug dosage to maintain optimal health.
Minor
While this interaction is unlikely to cause significant problems, it could intensify side effects or reduce the effectiveness of one or both medications. Monitoring for changes in symptoms and your condition is recommended, and adjustments may be made if needed to manage any increased or more pronounced side effects.
Onset
Rapid: Onset of drug interaction typically occurs within 24 hours of co-administration.
Delayed: Onset of drug interaction typically occurs more than 24 hours after co-administration.
Evidence
Level of documentation of the interaction.
Established: The interaction is documented and substantiated in peer-reviewed medical literature.
Theoretical: This interaction is not fully supported by current medical evidence or well-documented sources, but it is based on known drug mechanisms, drug effects, and other relevant information.
How To Manage The Interaction
Provides a detailed discussion on how patients and clinicians can approach the identified drug interaction as well as offers guidance on what to expect and strategies to potentially mitigate the effects of the interaction. This may include recommendations on adjusting medication dosages, altering the timing of drug administration, or closely monitoring for specific symptoms.
It's important to note that all medical situations are unique, and management approaches should be tailored to individual circumstances. Patients should always consult their healthcare provider for personalized advice and guidance on managing drug interactions effectively.
Mechanism Of Interaction
The theorized or clinically determined reason (i.e., mechanism) why the drug-drug interaction occurs.
Disclaimer: The information provided on this page is for informational purposes only and should not be considered medical advice. Always consult with a qualified healthcare professional regarding your specific circumstances and medical conditions.
Where Does Our Information Come From?
Information for our drug interactions is compiled from several drug compendia, including:
The prescribing information for each drug, as published on DailyMED, is also used.
Individual drug-drug interaction detail pages contain references specific to that interaction. You can click on the reference number within brackets '[]' to see what reference was utilized.
The information posted is fact-checked by HelloPharmacist clinicians and reviewed quarterly.