I insert 23 gauge needle in bottle of bac.water and draw amont needed.Insert in pep vial in a way that needle is at a angle and close to side of vial,slowly inject bac.water until syringe is empty.Swirl contents gently [don't shake] until dissolves.Keep in fridge. P.S. on 5mg vial I use 2 ml water this give you 25 mcg a iu on insulin syringe