Double-bagged in a ziploc.
For things that were "optional" I packed them in our regular luggage in amongst the clothes for padding.
The things that were not "optional" I carried on (put in the ziploc and presented at security like you're supposed to do) even though they weren't prescription meds. I didn't have a problem at all. The things that needed to be refrigerated I packed in the ziploc, then put them in one of the kid's lunchboxes with an ice pack, and carried them on that way. It kept everything cold enough until we got it into a fridge.