Yes new uses of existing drugs can be patented:

https://www.drugpatentwatch.com/blog/patenting-new-uses-for-...

This is clearly made by an LLM and thus not a credible resource.

From:

https://pmc.ncbi.nlm.nih.gov/articles/PMC9336118/

"COM claims can be difficult to gain for repurposed compounds, as the patentee must somehow differentiate their patent claims over what is in the public domain and present data that the drug is a credible candidate for the new indication [41, 42]."

citing

41 https://pubmed.ncbi.nlm.nih.gov/32241561/

42 https://pubmed.ncbi.nlm.nih.gov/30310233/