I don’t know, but I did read a report (I’ll see if I can find the link) which said that pharma drugs really last 5 years beyond expiration date. I suppose it depends on what it is - I think some medications in alcohol base (Codein cough syrup) can get more concentrated.
Thats true generally but tetracycline based drugs do become toxic after expiration.
“Expired tetracycline pills can degenerate and, if ingested, cause Fanconi syndrome. Patients should be instructed to discard the antibiotics when they expire.”