Risk of taking herbals in people with heart disease

Researchers from the Mayo Clinic in Minnesota and Arizona collaborated to review the risks of herbal:drug interactions.

The abstract is a bit skimpy on details, but the American Pharmaceutical Association has a nice summary, which will be summarized further here.

First, the details.

• 16 herbal products are potential problems.

And, the results.

• St John’s wort
  • Induces cytochrome P450 (CYP)3A4, an enzyme involved in the metabolism of more than 50% of all prescription medications, including many used to treat heart arrhythmias, high blood pressure, and high cholesterol.
• Motherwort
  • Inhibits the ability of blood to clot and increases the risk of bleeding.
• Ginseng
  • Potentially toxic to the kidneys
  • May lower or raise blood pressure
  • Interacts with the blood thinner, warfarin (Coumadin), which increases the risk of bleeding
• Ginkgo biloba
  • Increases the risk of bleeding when used with antiplatelet, anticoagulant, or antithrombotic agents (blood thinners)
• Garlic
  • Increases the risk of bleeding in patients using anticoagulant or antiplatelet drugs
• Grapefruit juice and black cohosh
  • Inhibit CYP3A4, which increases blood levels of…
    • Calcium-channel blockers
    • Cyclosporine
    • Statins
    • Midazolam (Versed)
    • Estrogen (Premarin)
    • Terazosin (Hytrin)
• Hawthorn
  • Enhances the activity of digoxin (Lanoxin), which could cause toxicity
  • Increases the risk of bleeding from thromboxane A2
• Saw palmetto
  • Increases the antiplatelet effects of warfarin, which increases bleeding risk
• Danshen
  • Increased antiplatelet effects and bleeding risk
• Echinacea
  • Increases the risk of liver toxicity from…
    • Statins
    • Fibrates (Atromid, Tricor, Lopid)
    • Niacin (Nicobid)
    • Amiodarone (Cordarone)
    • Tetrandrine (an alkaloid extracted from a Chinese medicinal herb traditionally used o treat high blood pressure)
  • Interferes with calcium channel blockers and may cause liver and/or kidney toxicity
• Aconite
  • Can cause cardiac arrhythmias, ranging from slow heart rate and low blood pressure to fatal ventricular arrhythmias
• Yohimbine
  • Decreases the effect of blood pressure drugs, including diuretics
• Gynura
  • Associated with liver toxicity
  • Decreased activity of angiotensin-converting enzyme
• Licorice
  • Potentiates the effects of spironolactone (Aldactone) and digoxin
  • Also, a risk of ventricular arrhythmias, including torsades de pointes (sudden death)

The bottom line?

Many drugs used to treat cardiovascular disease have a narrow therapeutic range. In other words, small changes in dosing or drug metabolism can lead to significant side effects.

If you’re a healthcare professional, you need to ask.

If you’re a patient, you need to tell the doctor what you are taking — including herbals.

4/5/10 15:29 JR