Hi lovedogs, welcome to Cruise-Chat! Congratulations on your up-coming cruise. I wish I could answer your question. I do know that there are pharmacies close to both ports in Cozumel, but don't know what all they carry. I would assume everything you can get here, you can get there, as long as you have a prescription. Hopefully, someone can answer your question from experience.
Best wishes and have a wonderful cruise!