You may be talking about Amifostine, a radio protectant that may help with mucocitis, dry mouth, also protects the kidneys from chemo, but read mixed reviews as far as the benefit vs the toxicities. It's given 30 minutes before radiation either by injection or IV, but read IV is more tolerable. I've seen more of it more a few years ago, but not as much lately, so it may not be used as much.
http://jco.ascopubs.org/content/18/19/3339.longPilocarpine is a pharmaceutical salivary stimulant, along with a few others, in addition, there are natural and OTC products to increase saliva.
As far as the Peg, if it's needed, use it. That's what it's there for. There are no medals given or any added bonus points to be received for tuffing without it, and being malnourished or dehydrated unnecessarily. Basically, he should be consuming at least 1/2 his body weight in liquids, 20% can be from food. There are water apps, calculators out there to configure based on height, weight, gender, activity, and mine comes to 128 ounces, and the peg sure comes in handy to do that, and will help flush the kidneys, especially with Cisplatin.
Good luck
