As long as you don't open the Pedialite bottle, it will keep until the expiration date. Chances are, with picking up your frogs, you won't need it, but it's nice to have for other problems that may crop up.
As Randy says, you don't need parasite medications on hand. In the first place, any medication of the sort that will kill a lung fluke or an intestinal parasite is going to also be somewhat detrimental to your frog, and each type of parasite requires a different medication. You need a diagnosis first, and that requires a vet and some lab work. So never medicate dart frogs arbitrarily on a guess. Parasitic medications for animals are available without prescription. Farmers and aquarium people use them all the time with impunity. Aquarium fish are usually cheap and expendible, belly up at any opportunity anyway, so who knows how many have been killed by treatment vs. disease? I treat my horses with parasite medications three times a year because I know there is an ongoing bot and strongyle infection yearly, but I wouldn't dream of treating my dart frogs in the same "preventive" manner. It's a much more delicate matter.
Even if some parasites should continue to exist in captive bred frogs, there is a certain tolerance and control that occurs. Many animals, including reptiles and ambhibians can live perfectly peacefully with a certain parasite "load," as long as they aren't stressed by other diseases that compromise their immune systems. As long as you receive healthy frogs from a reputable breeder and no other serious stresses or injuries occur, I don't think parasites should be one of your immediate concerns.
As usual, I've taken several paragraphs to say just what Randy said in a few words. Sorry, I'm just that way.
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Patty
Lost River, Idaho
4 D. auratus blue
3 D. galactonotus pumpkin orange splash back
5 D. imitator
4 D. leukomelas
4 D. pumilio Bastimentos