I've been giving Gwyn potassium gluconate for years now. I was in the pharmacy last week for some other stuff, and noticed that they carry potassium gluconate there as well. Is there any reason that I need to get one of the potassium gluconate products designed for pets, or can I just substitute in one of the human supplements? 'Cause it looks like it'd be easier and cheaper to get it from the drugstore than my vet. Thanks!