Tysabri May Lead to Liver Injury Within a Week After First Dose

Signs of hepatic injury may emerge as early as 6 days after starting Tysabri (natalizumab), an integrin receptor antagonist approved for treatment of multiple sclerosis and Crohn disease, the FDA and manufacturer have warned.

Such signs include elevated liver enzymes and total bilirubin. According to the drug's updated prescribing information, "the combination of transaminase elevations and elevated bilirubin without evidence of obstruction is generally recognized as an important predictor of severe liver injury that may lead to death or the need for a liver transplant."

The new label advises clinicians to warn patients about the potential risk and to discontinue the drug in those with signs of significant hepatic injury, including jaundice.