FAs might have objections to storing your materials in contact with ice that is to be used for people's drinks, not being able to guarantee its safety, etc. so I would suggest making plans to be self-sufficient. Maybe a small amount of dry ice of your own in a styrofoam container (just enough not to freeze the liquid contents) could be enough to get you through. Or alternatively, contact your doctor to see just how strict the refrigeration requirement is (in hours) -- it is probably survivable for a few hours more without great harm, but you should check.