I had Amifostine daily for all of my radiation treatments, and it really wasn't too bad. They would make sure Radiation would be ready for me on time, and give it immediately before I went down to the Radiation Lab. I would have some transient nausea that would hit at almost exactly the same time every day -- just about 5 minutes after I completed radiation and was walking to the car. Lasted about 15 minutes, but was gone by the time I got home.
As to how effective Amifostine is, I really couldn't say, because I don't know what my saliva situation would have been without it. I lost my two submandibular glands to neck dissection, so was challenged from the start. However, today, 3 years exactly from the day my biopsy results came back, I can eat anything, though winters are tougher than the rest of the year.
Good luck to your brother.