Unintended consequences: When medicine hurts more than helps

A study on how and why some drugs harm some livers could provide new insights and spur more research into individualized medicine.

By Susan J. Landers, AMNews staff. Aug. 15, 2005.

Severe liver damage caused by medications is rare, but when it does occur, it can be catastrophic, leading to liver failure and the need for a rapid transplant, or death.

Why this phenomenon happens -- why some people are injured by a drug that most can take without a problem -- is a medical mystery that several investigators are now trying to solve.

The liver, of course, is the body's guardian, providing protection from potentially harmful substances even as it stores vitamins and other nutrients from food and removes waste. But it is also vulnerable. For example, it is well known that the liver can be harmed by viruses (particularly hepatitis), excessive alcohol use and the abuse of certain drugs, especially acetaminophen.

It is also known, however, that prescription drugs and herbal products used as directed can cause severe liver injury to some people. The reasons behind these rare, idiosyncratic injuries are now being pursued by investigators. Is it genetic, environmental or a combination of both?

The answers to such questions could have wide-ranging implications.

Drugs were recently named by the Food and Drug Administration as the most frequent cause of acute liver failure in the United States, exceeding all other causes combined. And liver injuries are the major reason for the withdrawal of a drug from the market, for a new medication's failure to gain FDA approval, for restrictions on a drug's use and for warnings to physicians.

Considering this information in tandem with the important role drugs play as treatments and drivers of health costs underscores the need for answers.