Injecting - powder K to liquid. increasing solubility?

[fnord]

It seems like after a few IV shots more and more needs to be used at one time,this useally requires grandma to have to inject up to 2 full syringes of K,this can be quite anoying/confusing after the first one is administered...

how would one go about increasing the amount of K that can be dissolved in a given amount of water? grandma has tried heating the liquid up and then injecting before it cools(not good idea) and has tried adding a small amount of ethanol both worked to some degree but still required grandma to do 2 shots in a row to get to that happy special place.