I would add nothing at all to the urine. If you search on Google you will see a Japanese doctor who, along with colleagues, did extensive testing on the effectiveness of urine therapy. He said that those who rinsed out their mouths afterwards, and those who got it through intubation in their stomachs had "no efficacy". It is the contact with the back of the throat that is helpful according to him. The throat picks up info from the urine to know how to treat the body itself. He says that gargling - again without rinsing afterwards, and swallowing just a small amount is all that is needed from the urine.