Repurposing drugs used in other diseases may work for SARS-CoV-2. These drugs are already approved for humans and can be immediately used in humans. Researchers at the Chinese Academy of Sciences screened 3581 molecules and found 75 compounds showing 45% inhibition.
Further refining revealed that ceftazidime had a relative inhibition rate of about 81%. Ceftazidime is approved for treating bacterial pneumonia. Further research revealed that ceftazidime binds specifically to the spike protein receptor-binding domain (RBD) of the coronavirus.
This prevented the binding of the coronavirus to the human pulmonary alveolar epithelial lung cell. It also prevented the entry of the SARS-CoV-2 pseudovirus. The IC50 of ceftazidime was about 113µM and did not show any measurable toxicity up to 400µM.
This action of ceftazidime might be due to the chemical functionalities 2-aminothiazole, oxime with a terminal-exposed isobutyric acid, and positively charged pyridine. The strong binding of ceftazidime to the spike protein RBD suggests covalent bonding.