Rat study suggests liver danger, but doses must be very high
WEDNESDAY, Sept. 26 (HealthDay News) -- Very high doses of caffeine and acetaminophen (such as Tylenol), taken together, could lead to liver damage, researchers warn.
This combo produces a byproduct enzyme that's toxic to the organ, researchers from the University of Washington report.
This toxic twosome can occur not only by drinking caffeine while taking acetaminophen, the experts added, but also from large doses of painkillers that combine caffeine and acetaminophen. These painkillers are often used to treat migraines, menstrual discomfort and other conditions.
"Caffeine can interact with an enzyme that can form a toxic metabolite of acetaminophen in such a way that it increases the formation of that toxic metabolite," said lead researcher Sid Nelson, a professor of medicinal chemistry. "This can result in liver damage," he said.
In the study, Nelson's team tested the effects of acetaminophen and caffeine on E. coli bacteria. These bacteria had been genetically engineered to mimic a human enzyme in the liver that detoxifies many prescription and nonprescription drugs, explained the authors in a report in the Oct. 15 issue of the journal Chemical Research in Toxicology.
Nelson noted that it takes large qualities of caffeine to produce this reaction.
"Normally people wouldn't be ingesting that amount of caffeine," he said. "It would take 10 times the amount of caffeine found in a couple of cups of coffee," Nelson said.
His team found that caffeine triples the amount of a toxin called N-acetyl-p-benzoquinone imine (NAPQI) produced by the enzyme as it breaks down acetaminophen.
This same toxin is also produced during an interaction between alcohol and acetaminophen that's also well known to damage the liver.
In prior studies, Nelson's team had found that high doses of caffeine bo
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