Ketotifen (HC 20-511) is a second-generation, orally active, noncompetitive histamine 1 (H1) receptor antagonist and mast cell stabilizer. It inhibits 6-phosphogluconate dehydrogenase (PGD) in vitro and exhibits antiviral activity against SARS-CoV-2 and the Influenza virus. Ketotifen is also used in research on autoimmune encephalomyelitis (EAE) and in the prevention of asthma attacks.
