as long as it's not mixed it should be fine. once the ba is added it has to refrigerated. certain companies like i know norditropin is already mixed, which is why it has to be cold shipped.
Yeah, most you encounter wont be mixed yet and will just be the powder. Even in this case though I think its not supposed to be subject to too much heat for very long. The time it takes though to get to you isnt enough to ruin it though. Its always nice too to have a PO box at a store so that when it comes in it is in an air conditioned room. Never heard of any potency issues come about from exposure to summer heat if its the powder. If its liquid form they will ship with a cool pack.