In 2012, researchers published an article linking quinolone antibiotics to liver injuries in seniors.

Quinolone antibiotics are a class of synthetic antibiotics. This class of antibiotics, which includes Avelox, Cipro and Levaquin was the first purely-synthetic family of antibiotics.

Early families of antibiotics were all derived from naturally occurring chemicals. For example, a mold called Penicillium notatum produced a chemical called penicillin to kill bacteria. Researchers learned to harvest this chemical and produce it commercially, leading to the first modern antibiotics.

However, quinolone antibiotics were the first family of antibiotics to be completely artificial, having no known counterpart in nature. It was hoped that this meant that bacteria could not find ways to cope with quinolone antibiotics as they had started to with other types of antibiotics. While this was not the case, quinolone antibiotics proved as effective as previous groups of antibiotics and joined their ranks.

However, a study published in the Canadian Medical Association Journal found that patients using quinolone antibiotics like Avelox, and Cipro suffered a higher rate of liver failure than their peers. In this study researchers collected data from 144 Ontario patients over 65, who spent time in hospital between 2002 and 2011.

The researchers’ data found that there were six hospitalizations for liver injuries like liver failure or liver toxicity per 100,000 people taking quinolone antibiotics. Researchers employed a type of mathematics called statistical analysis to study their results. Scientists use this type of analysis to figure out the chance that their results are the result of coincidence.

Generally, for biology research projects, a connection between two factors is not considered “statically significant” unless there is a 95 percent or greater chance that the results are not a coincidence. This percentage is typically even higher in medical studies. Using these constraints, researchers found the strong link between liver injuries like liver failure and liver toxicity and Avelox, but Levaquin also had a statistically-significant link to liver failure and liver toxicity as well according to their paper.

Canadian public health regulators issued warnings for Avelox dating back to early 2010. This warning specifically warns of liver injury, which can include liver toxicity and liver failure. However, this study indicates that the risk may include other quinolone antibiotics, including Levaquin.

Lawsuits have been filed by patients who have allegedly suffered liver failure from quinolone antibioics. These liver damage lawsuits allege that drug makers were aware—or reasonably should have been aware—of the serious risk allegedly linked to these drugs. These quinolone lawsuits further allege that not only were drug makers aware of these risks, but that they failed to adequately protect the public, endangering lives while enriching themselves.