Biogen and AbbVie recently withdrew Zinbryta from the global market amid allegations that the drug is linked to encephalopathy causes.

Following Biogen and AbbVie’s voluntary withdrawal of Zinbryta from the global market, the United States Food and Drug Administration (FDA) is reviewing whether the multiple sclerosis drug is linked to encephalitis or if reports are due to other encephalopathy causes.

Zinbryta was approved in May 2016 and has since had a “complex safety profile”, FDA spokesperson Sandy Walsh states. As a result, the drug has mostly been prescribed to patients who did not respond well to other multiple sclerosis medication.

In August 2016, Zinbryta’s label was updated to include risk of liver injury, infections, immune-mediated disorders, and autoimmune hemolytic anemia. Since the drug’s release, the FDA’s Adverse Event Reporting System has received 1,200 reports of safety issues, 626 of which were serious cases and 25 of which involved a death.

Biogen and AbbVie voluntarily withdrew the multiple sclerosis drug following an investigation into the drug by the European Medicines Agency. The agency’s investigation was prompted my multiple reports of encephalitis and meningoencephalitis.

Encephalopathy is an inflammation of the brain and is characterized by flu-like symptoms such as fever, headache, muscle pain, weakness, nausea, light sensitivity, and more. In more severe cases, encephalitis causes confused thinking, seizures, or problems with senses and movement. The condition can lead to permanent disability and death.

So far, three cases of encephalopathy cases related to Zinbryta have been reported in the United States. However, a significant number of cases have been reported in Europe, Walsh said. It is unclear whether the cases are directly related to Zinbryta or whether the condition is due to other encephalopathy causes. The FDA is using worldwide data in their review, Walsh reports.

In addition to the label changes and the concerning number of reports, there have been reports that Zinbryta may lead to encephalopathy causes. Encephalopathy causes include immune-mediated disorders, which are known side effects of Zinbryta and warned on the drug’s U.S. label. Other encephalopathy causes include viral and bacterial infections.

The FDA’s approval system requires extensive clinical testing before a drug is released onto the market to ensure that it will not pose a serious risk to consumers. However, safety problems can still emerge when a drug reaches the market.

“[W]hen drugs are approved we know relatively little about their safety in the real world, and that’s the nature of our regulatory system,” says Dr. Caleb Alexander, co-director of the Johns Hopkins Center for Drug Safety and Effectiveness, speaking to MarketWatch. However, global market withdrawals are fairly uncommon and “reserved for settings in which there’s an especially entenable risk that can’t be managed through other regulatory actions”.

If you or a loved one experienced encephalitis or liver problems following Zinbryta use, you may be eligible to participate in a free Zinbryta lawsuit investigation. Legal action could potentially be taken against Zinbryta manufacturers to hold them accountable for side effects not included in their patient warnings. A Zinbryta lawsuit could recover compensation for medical expenses, loss of wages, pain and suffering, and more.