Jan. 27--NEW HAVEN -- Aspirin may be good for your liver, protecting it against damage from too much Tylenol and possibly even from obesity and alcohol abuse, according to a new study by a Yale physician.
A study by Dr. Wajahat Mehal, published in Monday's edition of the Journal of Clinical Investigation, shows that liver damage can be prevented by low doses of aspirin. Mehal is associate professor in the Department of Immunobiology at the Yale School of Medicine.
If it passes clinical trials, doctors will be able to prescribe inexpensive common aspirin to treat millions of people who have liver damage as a side effect of Tylenol or other drugs.
Mehal found that aspirin has a protective effect, preventing inflammation of the liver caused by many medications, including high doses of acetaminophen, which is sold as Tylenol and is an ingredient in other medicines. Just as hitting your thumb with a hammer brings redness along with the pain, "the Tylenol injury is the equivalent of the hammer," Mehal said Monday.
Other causes of liver inflammation include heavy alcohol use and obesity.
Inflammation is the body's response to injury or infection. If germs get into a cut, for example, the immune system, including white blood cells, launches an attack on the bacteria. The pain, redness and swelling means the wound is healing.
When the injury is not caused by an infection, however, the immune response actually attacks healthy cells and can cause damage to the affected organ.
"It activates a bunch of immune cells that go in there and kill the body cells," Mehal said. Aspirin "switches off the production of some inflammatory molecules called cytokines," which are similar to hormones.
"The liver is much more on a hair-trigger for this inflammatory response," he said.
The findings mean that new drugs that have failed clinical trials because they damage the liver might be looked at once again because they can be taken with aspirin.
Tylenol accounts for most drug overdoses in the U.S. and other developing countries. It is so toxic that half a bottle can be fatal, Mehal said, adding that if acetaminophen came to market today the Food and Drug Administration likely would not approve it.
Mehal added, though, that "Tylenol is a very safe medication as long as it's taken within the dose guidelines" and doesn't have the stomach-irritating side effects of aspirin or ibuprofen (which is marketed as Advil and Motrin.)
Some people take too much Tylenol, however, when they use multiple cold remedies. Tylenol itself damages the liver, and the immune response adds to the injury. Severe liver disease results in jaundice, feelings of weakness and nausea, Mehal said.
Tylenol is not the only medication that causes liver damage, however. Many, including antiretrovirals taken for HIV and AIDS, as well as cholesterol-lowering drugs known as statins, do so. Doctors monitor the effect on the liver when prescribing such drugs. Aspirin "will likely help with a variety of different kinds of medication," Mehal said.
He said the dosage still has to be worked out, but that it would be low enough not to cause stomach damage. "It'll be in the range we know people can take, in the milligram range," he said.
Also, those who take low-dose aspirin to protect against heart attacks and stroke likely would not receive the benefit to the liver from a daily 81-milligram dose because the protective effect would not last long enough. "The anti-inflammatory effect (lasts) much less than a day," Mehal said. Small doses several times a day is the more likely regimen, he said.
Patients should not ask their doctors about taking aspirin for liver damage yet, though, Mehal said. "I can't tell them w h i c h d o s e t o g i v e t h e i r patients. I can't tell them how frequently to take it. ... They don't have the information to write a (prescription)."
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