Levofloxacin: dysglycemia and liver disorders

A powerful antibiotic used to treat pneumonia, urinary tract infections and other ailments is suspected of causing diabetes like and liver problems in dozens of Canadians, five of whom died, a new Health Canada report reveals.

As the department tries to gauge the extent of the problem, doctors are being urged to report any cases of blood-sugar level upset or liver damage that may be linked to levofloxacin.

But one specialist cautioned yesterday that such side effects, if truly caused by the drug, are likely rare and should not discourage use of what can be a potent weapon against infection.

Scientists have long been aware that some antibiotics in the fluoroquinolone class could occasionally trigger blood-sugar and liver adverse reactions, but the volume of reports on levofloxacin, whose brand name is Levaquin, grabbed the attention of Health Canada officials.

"Certainly the number of reports prompted us ... to start looking at this medication," said Melissa Hunt, acting manager of the department's marketed pharmaceuticals and medical devices bureau.

"Levo did raise a bit of a signal so we certainly wanted to get that information out there and stimulate the reporting."

A spokesman for Janssen- Ortho, the company that manufactures Levaquin, could not be reached for comment.

The fluroquinolone drugs are called broad-spectrum antibiotics, effective in combatting a wide range of bacterial infections.

An article on the drug appears in Health Canada's latest newsletter on adverse reaction reports. The reports are submitted by doctors, pharmacists, other health professionals and drug companies when they suspect a product may have caused a serious side effect. They are considered less than definitive, however, because there is no comparison to patients not taking the drug, no indication of how likely patients are to experience the side effect and often no details on underlying medical conditions or other drugs that may have caused the adverse reaction.

The article notes that Health Canada received 22 reports of disturbed blood-sugar levels between January, 1997, and June, 2006, attributed to levofloxacin. Most were hypoglycemia, or dangerously low blood sugar.

More than half the patients were being treated for diabetes, with ages ranging from 29 to 92. Some of the suspected side effects were severe enough that people ended up in hospital, Ms. Hunt said.

Over the same period, levofloxacin was suspected in five reports of liver failure, nine of hepatitis and one of hepatorenal syndrome: kidney failure linked to liver disease. There were another 29 reports of other liverrelated side effects linked to the drug.

All of the five patients who died were elderly, had more than one medical condition and took other drugs, too, Ms. Hunt noted.

The product label information for the antibiotic contains some mention of possible blood-sugar or liver reactions, but Health Canada may require more warnings as it collects additional information, she said.

Another drug in the same class, trovafloxacin, was pulled off the market in the late 1990s because of liver adverse reactions. And gatifloxacin is known to sometimes cause glycemic problems, said Dr. Grant Stiver, a Vancouver-based infectious disease specialist.

But he said he is not concerned about such side effects in levofloxacin.

"I would say that these are rare," said Dr. Stiver, a professor at the University of British Columbia. "I've used all these drugs for many years and probably treated a thousand patients with them and I don't remember any patient on levofloxacin developing liver toxicity."

Levo and other drugs in the same broad-spectrum class are "very, very useful" because they can be prescribed by family doctors unsure of the exact nature of an infection or unable to have a test done to precisely pinpoint the bacteria, he said. They also are effective against bugs, like streptococcus pneumoniae, the number one cause of pneumonia, which have become resistant to many other commonly used antibiotics, Dr. Stiver said.

Source: www.canada.com
7th January 2007

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