I have never heard of the .med extension and according to google there are probably dozens of different programs that use that extension. One that almost makes sense is IrfanView, but it is a graphics program so it could be a screen shot and not actual data.
Have you tried opening it up in notepad or something similar just to see what happens? I would hope that the person that gave you the data could get more information about the file.
Hopefully someone will come along with an answer. But if they don't it could be next to impossible to decode if it is some sort of custom binary format.