There are also numerous discussions about it in this group. If you go to the main MAC & Bronchiectasis group page and put NAC in the search box for Search this Group, you will find many discussions and posts.
I was a little hesitant at first, but tried it to clamp down on exacerbations. In the past 2 years, I have only had two - only one of which required treatment. Previously, I had 4-5 episodes a year.