Chicharronita, sorry, I don't know the answer to your questions, and I think they are good ones.
I just wanted to add that after much experimentation, I found a way to get my 2 year old to take SA pretty easily. I mix it in strawberry jam. I have been giving him 1/2 teaspoon of SA at a time, in one teaspoon of strawberry jam (the fruit juice-sweetened kind). He also will take it in a teaspoon of honey, but the jam masks the taste even better. As others have posted, it is sometimes really hard to get a child to take SA. This finally worked for me, and I am happy to report that after two days of about 10 grams of SA, his chronically runny nose has ceased running!
Thanks MT, for giving me the idea and the knowledge to back it up.