Hello and thank you for using PetCoach! Sorry to hear that this happened.
When antibiotics are ingested in toxic amounts, it can result in mild to severe signs ranging from gastrointestinal signs (e.g., drooling, vomiting, diarrhea, inappetance, discolored teeth), metabolic signs (e.g., skin lesions, liver failure, kidney failure, etc.) to central nervous system signs (e.g., tremors, seizures, death).
I would advise contacting your local emergency vet hospital or contact Poison Control
https://www.aspca.org/pet-care/animal-poison-controlSorry this happened with your pet. Another option would be to contact the drug manufacturer directly if that information can be learned. I'm hoping for a positive outcome with your kitty!!