Most medicated feeds do not have antibiotics. They contain amprolium which is a thiamine blocker not an antibiotic. It also has a very short withdrawal period and is unlikely to cause any harm if you did ingest some. I also have yet to talk to anyone who can say for certain that it does or does not get in to the eggs. I wouldn't really worry about it. I've eaten eggs from chickens on medicated chick starter. I couldn't get gamebird feed which is what I normally feed so both chicks and hens can eat it. For one bag worth, a couple weeks, they all ate medicated starter instead. If you don't use layer feed you just have to make sure there is oyster shell available. I wouldn't continue to feed starter because they could end up with a vitamin deficiency but I wouldn't worry about finishing the bag if it were me. I wouldn't sell or give away those eggs though because of the odd chance of someone having a problem with them.
Of course this might not hold true if your bag of starter contains something other than amprolium.
