Thrombocytopenia during avacopan administration: A case report.

Abstract

Avacopan is a novel C5a receptor antagonist recently approved for the treatment of microscopic polyangiitis and granulomatosis with polyangiitis. To our knowledge, thrombocytopenia induced by avacopan has not been reported. We report a case of a 78-year-old man with microscopic polyangiitis who developed rapidly progressive glomerulonephritis (RPGN) and vasculitis neuropathy. After developing RPGN, he was treated with prednisolone, which was ineffective. As the dosage of corticosteroids was decreased, he developed impaired dorsiflexion of the left ankle, tingling and numbness in his feet, consistent with vasculitis neuropathy. After a 3-day administration of methylprednisolone, we started avacopan and prednisolone 20 mg/d to reduce the corticosteroid dosage. One week after starting avacopan, platelet counts began to decrease, eventually leading to the cessation of the drug. The possibility of thrombotic microangiopathy and heparin-induced thrombocytopenia was considered unlikely given the clinical course and laboratory studies. After 3 weeks of avacopan cessation, platelet counts began to increase, suggesting avacopan as the most probable cause of thrombocytopenia. Our case highlights the importance of postmarketing surveillance of avacopan to identify its adverse events that were not reported in clinical trials to ensure its safe use. Clinicians should carefully monitor platelet counts when using avacopan.

• Authors: Nobuhisa Morimoto, Takayasu Mori, Shingo Shioji, Hatsumi Watanabe, Keigo Sakai, Katsuo Mori, Ayumi Yamamura, Asami Hanioka, Yuichiro Akagi, Tamami Fujiki, Shintaro Mandai, Yutaro Mori, Fumiaki Ando, Koichiro Susa, Soichiro Iimori, Shotaro Naito, Eisei Sohara, Shinichi Uchida
• Journal: International journal of rheumatic diseases (Int J Rheum Dis) Vol. 26 Issue 8 Pg. 1603-1607 (Aug 2023) ISSN: 1756-185X [Electronic] England
• PMID: 36880594 (Publication Type: Case Reports)
• Copyright: © 2023 Asia Pacific League of Associations for Rheumatology and John Wiley & Sons Australia, Ltd.

Chemical References

• avacopan
• Aniline Compounds
• Methylprednisolone
• Antibodies, Antineutrophil Cytoplasmic

Topics

• Male
• Humans
• Aged
• Microscopic Polyangiitis (drug therapy)
• Thrombocytopenia (chemically induced, diagnosis, drug therapy)
• Aniline Compounds (adverse effects)
• Methylprednisolone (therapeutic use)
• Granulomatosis with Polyangiitis (drug therapy)
• Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis (drug therapy)
• Antibodies, Antineutrophil Cytoplasmic