Tiny early research found that green tea drinkers have lower levels of nadolol in the blood

Monday, January 13, 2014 (Health Day News)-A new small study suggests that drinking green tea may reduce the effects of the drug Nadolol (Corgard) used to treat high blood pressure.

After drinking water or about three cups of green tea a day for 14 days, the researchers gave 10 volunteers a single dose of 30 mg nadolol.

When the researchers tested the blood levels of the drug, the concentration of the drug in the green tea group was 76% lower than that in the water-drinking group.

According to the authors of the study, this means that “patients receiving nadolol should avoid taking green tea.” They published the results of the study in the Journal of Clinical Pharmacology and Therapeutics online on January 13.

Researchers include Shingen Misaka of Fukushima Medical University in Japan and other universities in Germany, Japan and Italy.

"People who take nadolol and drink green tea should be aware of this potential interaction and discuss this with their doctor," suggested Dr. Gregg Fonarow, a professor of cardiology at the University of California, Los Angeles and a spokesperson for the U.S. government. Heart Association. He reviewed the findings, but did not participate in the study.

Nadolol is not the only drug that interacts with food or drink. For example, according to the US Food and Drug Administration, grapefruit and grapefruit juice can interact with drugs, such as cholesterol-lowering drugs and some blood pressure drugs.

The researchers of this new study said that the ingredients in green tea are thought to interfere with the absorption of the drug in the intestine.

Nadolol is a blood pressure lowering drug called a beta blocker that is used to treat high blood pressure and angina, which is chest pain associated with heart disease.

According to the American Heart Association, beta-blockers generally reduce stress by reducing heart rate and cardiac workload and reducing blood output.

Fonarow said that in the United States, nadolol is used less frequently than other beta blockers.

"This is not a commonly used beta blocker," agreed Dr. Suzanne Steinbaum, a cardiologist and director of women's heart health at Lenox Hill Hospital in New York City and spokesperson for the American Heart Association Go Red for Women campaign.

Steinbaum said the limitation of this new study is that the number of patients included is very small, only 10. She believes that, at least in the United States, tea consumption is unusual. "It is rare to see a patient drinking more than two cups of green tea a day," she said of her patient.

Fonarow said the results may only apply to green tea and nadolol. "It is not clear whether those receiving other heart medications and drinking green tea need to worry, or whether these findings apply to black tea," he said.

In addition, although the study showed that patients who drank green tea had lower levels of nadolol, a causal relationship could not be established. The researchers pointed out that larger studies are needed to understand how green tea reacts with drugs such as nadolol.

The research was partially funded by the Ministry of Education, Culture, Sports, Science and Technology of Japan.

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