Foxglove and High Blood Pressure

By Medical Discovery News

Sept. 8, 2012

Foxglove

Few pharmaceutical companies extract drugs from plants anymore, but a medication commonly prescribed for heart attack patients continues to come from the colorful flower foxglove. In addition, the plant may possess another life saving quality – the ability to lower blood pressure.

Foxglove, or Digitalis lantana and Digitalis purpurea, are historically important plants. The family of tall spires blooming with mostly purple flowers now has species growing all over the world, particularly along roadsides and in gardens in America. Herbalists, healers, and physicians in Ireland and Wales called it feverfew as far back as the 13th century. They used it with wine as an expectorant and an antiseptic. Native Americans brewed tea from its dried leaves to treat leg swelling caused by heart problems. In 1650, Foxglove was included in the “London Pharmacopoeia,” and then used by New England colonists by the mid-1700s.

Today, Foxglove leaves are used to make digoxin, which is commonly prescribed to treat congestive heart failure or atrial fibrillation, an irregular heartbeat. The drug increases the force of the heart’s contraction and slows its electrical impulses to regulate the rhythm.

Scientists have discovered digoxin could also treat high blood pressure.  Researchers from the University of Michigan learned a protein, RGS2, works protectively in the body to keep blood pressure in check. They found that low levels of this protein correlate with high blood pressure.

They also theorized if they could increase the body’s RGS2 levels, blood pressure would drop. Hoping an RGS2-boosting drug already existed, the team began testing thousands of medications. Not only did digoxin raise these protein levels in lab-grown cells, but it did so in mice by two to three times. Digoxin seems to work by slowing the normal degradation of the protein.

Studies on the mice showed that after seven days of being on digoxin, RGS2 levels increased in both heart and kidney tissues compared with mice not given the drug. Further tests are needed to prove that using digoxin to raise these protein levels does indeed lower blood pressure in humans. It’s also important to study long-term use of the drug.

Digoxin can be quite toxic. Since the body can’t process it quickly, the drug can build up and cause serious health problems. Symptoms of foxglove poisoning are pain in the mouth or throat followed by vomiting, diarrhea, severe headache, and irregular pulse, breathing, and heartbeat. A severe poisoning can cause convulsions and death.

Millions of Americans could benefit if further testing shows digoxin does lower blood pressure. One third of Americans lives with high blood pressure, also called hypertension. Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps blood. Blood pressure that’s too high leads to coronary heart disease, heart failure, stroke, kidney failure, and many other health issues.

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