The FDA has asked Amgen to voluntarily withdraw the drug avacopan (Tavneos), which is used to treat vasculitis associated with anti-neutrophil cytoplasmic autoantibodies (ANCA). The reason is the risk of liver damage. Amgen has announced that it will not withdraw the drug from the market. Avacopan is an oral complement inhibitor approved by the FDA in October 2021 as adjunctive therapy for severe active ANCA-associated vasculitis in adult patients. The treatment blocks C5aR1 receptors, reducing inflammation and protecting organs such as the kidneys and lungs. Common side effects include nausea, headache, diarrhea, fatigue, and high blood pressure. Serious risks include hepatotoxicity with elevation of liver enzymes, infections such as pneumonia and angioedema, so regular monitoring of liver function tests every 4 weeks after the first 6 months is recommended.