Adderoll

I found the Adderoll story to be interesting. I liked that the reporter began the story with a scripted voice over because I felt that it gave us an accurate feeling about what to expect from the story. It reminded me a lot of an NPR story in the way it was written and ordered. I appreciated that the reporter included an interview of an "expert" on the topic, who discussed the negative effects etc. What I am wondering is how acceptable it is in a radio story to include an anonymous source? I understand why the person chose to remain nameless (because he was taking the drug without a prescription), but is this acceptable?