Six tablets were discovered in a tin box onboard an ancient Roman shipwreck, found off the coast of Italy.
Samples of the fragile material revealed that the pharmaceuticals contained animal and plant fats, pine resin and zinc compounds.
Writing in the Proceedings of the National Academy of Sciences, the researchers said the medicine might have been used to treat eye infections.
"I am surprised by the fact we have found so many ingredients and they were very well preserved considering it was under water for so much time," said Maria Perla Colombini, professor of chemistry from the University of Pisa.
The shipwreck that the tablets were found on dates to 140-130 BC, and was thought to have been a trading ship sailing from Greece across the Mediterranean.
It was first discovered in 1974 off the coast of Tuscany, and explored during the 1980s and 1990s, but it is only now that the tablets have been fully investigated.
"We used a very thin scalpel to detach a small flake of substance to be analysed," explained Professor Maria Perla.