eCardioVascular Beat

Common herbal remedies’ interaction with medications

Naji Hamdan, M.D.

Cardiology, Providence St. Vincent Medical Center
Northwest Cardiologists

More than 15 million people in the United States consume herbal medicines. Many patients come in for an evaluation carrying bags filled with herbal supplements, questioning how safe these are when combined with other medications.

Health care providers should have a good knowledge of herbal remedies and their side effects to identify possible herb-drug interactions.

The following is a discussion of common herbal products – their uses, side effects and potential drug-herbal interactions, especially in patients with cardiovascular disease.

Hawthorn

Known as the wise man’s digitalis, hawthorn has been used for centuries. Legend has it that the crown of thorns placed on the head of Jesus was made of hawthorn.

Traditionally, hawthorn has been used for various cardiac conditions ranging from irregular heartbeat, hypertension and angina to congestive heart failure. It has vasodilatory and positive inotropic effects resulting in an increase of coronary circulation.

Side effects

• Nausea
• Tachycardia
• Hypotension

Herb-drug interactions

• If used with anti-hypertension medications, it can result in hypotension by increasing the vasodilatory effect.
• It increases the effect of digoxin and counters the effect of phenylephrine.
• It inhibits the biosynthesis of thromboxane A2, leading to increased bleeding risk if taken with anti-platelet or anticoagulation medications.

St. John’s wort

The plant blooms around June 24 in Germany, the traditional birthday of St. John the Baptist. When rubbed, red pigments release the active ingredient hypericin, which is said to symbolize the blood spilled when St. John was beheaded.

One of the top-selling herbs in the United States, St. John’s wort is used for the treatment of mild to moderate depression, anxiety and sleep disorders.

Side effects

• Dizziness
• Confusion
• Sedation
• Fatigue
• Photosensitivity
• Light sunburn

Herb-drug interactions

• Multiple herb-drug interactions occur through the induction of the cytochrome P450 enzyme CYP3A4. This results in an increased metabolization of these drugs, which decreases their concentration and clinical effect.

• Common drugs metabolized by the CYP3A4 include:

  • Amiodarone
  • Metoprolol
  • Carvedilol
  • Amlodipine besylate
  • Flecainide
  • Macrolides
  • Atorvastatin
• When used with Coumadin it causes subtherapeutic levels of anti-coagulation.
• Avoid using with transplant recipients, patients with atrial fibrillation and patients with prosthetic cardiac valves.
• It may also contribute to serotonin syndrome. When used with other drugs, it elevates 5-HT levels in the central nervous system.

Ginseng

In Mandarin Chinese, the word ginseng literally means “root of man,” referring to the root’s forked shape that resembles the human body.

It is classified as an adaptogen, a substance that helps the body resist the effects of physical and environmental stress.

Side effects

• Because of ginseng’s side effects, it is suggested to limit use to three months, stop for a month, then resume.
• If consumed with excessive coffee and smoking, it may cause arrhythmias.

Germanium is a contaminant that can be nephrotoxic by damaging the cell of the loop of Henle, thereby decreasing responsiveness to diuretics.

Herb-drug interactions

• Caution should be used when ginseng is administered with anti-hypertension medications since it has a hypotensive and hypertensive effect.
• If used with Coumadin it decreases bleeding time.
• Ginseng potentiates the effect of digoxin.
• It interacts with antidepressants, causing manic episodes.
• It causes low blood sugar and should be avoided in diabetic patients.
• Avoid using ginseng in women on hormone therapy because it can produce effects similar to those of estrogen.

Garlic

It has been used throughout history for both culinary and medicinal purposes. In both world wars it was used as an antiseptic to prevent gangrene. Garlic is used as an anti-bacterial, anti-viral and anti-fungal agent. It is also said to lower cholesterol.

Side effects

• Halitosis secondary to allyl methyl sulfide, a gas that is absorbed into the blood and travels into the lungs and skin. (Tips to clear garlic breath: eat fresh parsley and use a sauna to accelerate AMS from the body.)
• Some people suffer allergies from garlic, resulting in irritable bowel, diarrhea, mouth and throat ulceration, nausea and breathing difficulty.

Herb-drug interactions

• Garlic increases bleeding risk if used with aspirin, Plavix or Coumadin. Discontinue use 10 days before elective surgery.

Liquorice

The active compound in this legume (related to beans and peas) is glycyrrhizin, a sweetener that is 50 times as sweet as sucrose, a food and tobacco flavoring.

Medicinal uses include treating peptic and aphthous ulcers. It’s also used as a mild laxative, an anti-viral agent for shingles, and a treatment for oral and genital herpes.

Side effects

• The glycyrrhizin component can mimic the effects of aldosterone, resulting in hypernatremia and hypokalemia leading to hypertension, muscle cramping and arrhythmias.
• Water is also retained, leading to swelling and bloating.

Black cohosh

The root of this herb is used to decrease menopausal symptoms including hot flashes and night sweats, and to treat premenstrual symptoms.

Side effects

• Headache
• Weight gain
• Abdominal discomfort
• Nausea and Vomiting

Herb-drug interactions

• Black cohosh contains a small amount of salicylic acid, so people allergic to aspirin should avoid it.
• Black cohosh inhibits the CYP3A4, so caution should be used when it is administered with drugs metabolized by the CYP3A4 system. (See St. John’s wort, above.)

Red yeast rice (RYR)

Red yeast rice is the product of yeast that is grown on rice. It’s the ingredient that makes Peking duck glow red.

RYR contains several compounds collectively known as monacolins, a substance known to inhibit the syntheses of cholesterol. One of these, monacolin K, is a potent HMG-CoA reductase known as Mevacor.

When the FDA discovered that RYR contained a substance found in a prescription drug, it banned red yeast rice products that contained lovastatin. In 2003, red yeast rice products began to reappear. Many of them avoided the FDA restriction by not having appreciable monacolin content.

Side effects

• Abdominal pain
• Headache
• Muscle pain and others
• Similar to HMG-CoA side effects

Herb-drug interactions

• RYR should not be taken with statins as it may increase the risks of the side effects, including liver damage.
• Taking RYR with cyclosporin increases the blood level of red yeast and may cause rhadomyolosis.
• It increases the risk of bleeding if taken with aspirin, Plavix and Coumadin.

Ginkgo

It is mainly used as a memory and concentration enhancer, anti-vertigo and anti-tinnitus.

Side effects

• Excessive bleeding
• Seizures
• Headaches
• Digestive problems and muscle weakness

It should be avoided with people who have bleeding disorders or epilepsy.

Herb-drug interactions

• Can increase the effect of anti-platlet and anti-coagulation drugs.
• Avoid using with cyclosporin because it can decrease the effect of this drug.

As the popularity of herbal supplements continues to rise, so does the possibility that your patients are mixing one or more of them along with prescribed medications. So please keep these and other popular herbal remedies in mind when reviewing a patient’s drug interactions.