Zinbryta serious side effects reportedly include encephalitis, a life threatening inflammation of the brain.

Multiple sclerosis is a neurological autoimmune condition in which the body attacks myelin, the sheath that insulates the nerves and helps conduct neurological signals. Degradation of myelin can cause a variety of neurological symptoms and deterioration of neurological connections in the brain and spinal cord.

The U.S. Food and Drug Administration (FDA) approved Zinbryta in 2016 to treat relapsing multiple sclerosis. Zinbryta works to treat multiple sclerosis by binding to immune system cells and reducing the cells’ activity to prevent attacks on the myelin.

However, the drug has been associated with severe side effects since it was approved, including liver problems and immune-mediated disorders. These potential side effects prompted the FDA to only recommend the drug to patients who hadn’t responded to two or more other treatment methods.

In early 2018, further Zinbryta serious side effects were uncovered when the European Medicine Agency (EMA) released evidence that the multiple sclerosis drug was linked to encephalitis.

Encephalitis is an inflammation of the brain commonly caused by viral infections. Individuals with encephalitis often present with flu-like symptoms including a fever and headache. In some cases, encephalitis can be life threatening and present with symptoms such as seizures, hallucinations, paralysis, muscle weakness, hearing problems, and loss of consciousness.

Treatment for encephalitis will vary depending on the severity of the condition but may include fluids, anti-inflammatory drugs, antiviral drugs, anticonvulsant medications, and breathing assistance.

According to the EMA’s Pharmacovigilance Risk Assessment Committee (PRAC), 12 cases of inflammatory brain disorders were reported around the world in Zinbryta patients. Patients reportedly experienced encephalitis and meningoencephalitis (inflammation of the membranes around the brain and spinal cord) while on the drug. Three of the patients reportedly died due to inflammatory brain conditions.

Due to these cases, the EMA recommended that healthcare professionals take caution and carefully monitor Zinbryta patients for encephalitis. Additionally, the drug was no longer authorized in the European Union.

“Patients could be at risk from the start of treatment and for several months after stopping treatment, and it is not possible to predict which patients will be affected,” the EMA said in a press release. “The PRAC, therefore, confirmed its previous conclusions that risks of Zinbryta outweigh its benefits for patients with multiple sclerosis.”

However, Zinbryta manufacturers soon took matters into their own hands. In March 2018, Biogen and Abbvie responded to the reports of Zinbryta serious side effects by voluntarily withdrawing the drug from the global market.

“As a result, FDA is working closely with the manufacturers to help ensure a well-organized withdrawal from the market in the United States, and to ensure that health care professionals have the information they need to carefully transition their patients using Zinbryta to another treatment,” the FDA noted in their announcement.

The drug was available for a short time after the announcement so that patients could smoothly transition to another treatment option, but no new patients were authorized and no new patients joined Zinbryta clinical trials.