It's the phosphate salt vs. the sulphate one used in the human medicine (Plaquenil). Both counterions get used in medicines, but it's tough to say in general i

It's the phosphate salt vs. the sulphate one used in the human medicine (Plaquenil). Both counterions get used in medicines, but it's tough to say in general if it matters: sometimes it makes a difference, other times it's just whatever's easier/cheaper to make.