By Kathryn Doyle
NEW YORK (Reuters Health) - Men taking drugs in the fluoroquinolone family were twice as likely to suffer serious kidney problems as men not taking the powerful antibiotics in a new study.
When the participants, aged 40 to 85 years old, also took blood pressure medications known as ACE inhibitors, their kidney risk rose to nearly five times that of similar men not taking fluoroquinolones, which include ciprofloxacin, levofloxacin and moxifloxacin.
Because they work on a "broad spectrum" of bacterial species, fluoroquinolones are widely used to treat intestinal, urinary tract and respiratory infections - often when other drugs have failed to work.
"I think that in some cases older men will (still) need these types of antibiotics," said Dr. James L. Pirkle, Jr., a nephrologist at Wake Forest Baptist Health in Winston-Salem, North Carolina, who was not involved with the study.
"However, this paper is important to raise awareness that in certain populations, providers need to be aware of the increased risks," Pirkle told Reuters Health by email.
The list of fluoroquinolones' known possible side effects includes irregular heartbeat, insomnia and allergic reactions. But kidney failure is only noted as a rare event, so prescribers don't usually take it into account, according to the U.S. and Canadian team who published the new findings in the Canadian Medical Association Journal.
To see how common serious kidney injuries are in people taking fluoroquinolones, the researchers compared 1,292 men admitted to hospitals with acute kidney injuries to 12,651 similar men hospitalized without that particular diagnosis, and looked at who was taking or had recently taken a fluoroquinolone drug.
They found that 8 percent of the patients with kidney injury were currently taking the drugs when admitted to the hospital compared to 4 percent in the other group.
One in 1,500 people given a fluoroquinolone had acute kidney injury, twice as many as those not taking the drug.
But the absolute risk for any individual is still small, the researchers noted - about six to seven cases of acute kidney injury per 10,000 patients taking a fluoroquinolone per year.
Most people who take the drugs will probably not experience kidney problems, said one of the study's authors, Mahyar Etminan of the University of British Columbia in Vancouver.
"However, if you look at it more globally, if around 40 million people take these drugs annually this may translate to thousands of patients getting acute kidney injury solely due to fluoroquinolone use," Etminan told Reuters Health.
Indeed, about 40 million prescriptions for fluoroquinolones are dispensed annually in the U.S., Etminan said. That may be more than necessary because evidence indicates they are sometimes used when other, safer antibiotics would also work or when the ailment is actually a virus, which does not respond to antibiotics.
"There are a number of antibiotics available to treat infections, and each has a different spectrum of organisms that it is able to kill as well as different side effects," said Rachel Eyler, an assistant clinical professor in the School of Pharmacy at the University of Connecticut in Storrs.
"In some cases there are alternatives, and in other cases a fluoroquinolone may be the best choice for a patient," Eyler, who was not involved in the study, told Reuters Health by email.
To get the same potency with different antibiotics, "sometimes it may be necessary to prescribe two antibiotics (vs one fluoroquinolone) which may be less convenient for a patient and hence why MDs prefer a fluoroquinolnoe," Etminan told Reuters Health by email.
Due to the nature of the study, it's impossible to say how severe the kidney problems were or what other factors may have been at work in each patient, like dehydration, that could have caused the kidney problems, Pirkle noted.
But he agrees that doctors currently prescribing fluoroquinolones may not be as concerned about kidney problems in older men as they should be.
"Older men who may have failed on other antibiotics and have a serious infections may require this but most men (or women) probably don't need to be put on these antibiotics" until safer options have been tried, Etminan said.
SOURCE: http://bit.ly/ZlHFhj Canadian Medical Association Journal, online June 3, 2013.