I guess you already know how to open the inventory by now, so it's not a question of doing that wrong. Is it possible that you have to do some action other than normal opening of inventory in order to give Steiner the medicine? Maybe just talking to him automatically gives it to him?
If the saved game doesn't work, the Hints forum is a better place to ask. Maybe the save only works with some versions of the game -- or maybe it has to be applied in a specific way in order to work.
I don't own the game. I'm not fond of "sequels" where they sacrifice the gameplay and stability of the original game(s) in the name of high resolution graphics and compatibility with consoles. Since I lack first hand experience with the game, someone else may have better suggestions.