I dont know of anything that deadens the throat and dont belive they would help if it did. Most people with sensitive gag reflexs gag when their throat is numbed. Now just for making things more pleasant: try  "Good Head Gel" comes in 6 different flavors. I keep it in my toy kit and more than one provider has shown her approval.  Easy to get online at  Mypleasure.com  also available at most adult toy stores.  Anything to make a lady more receptive. They also have some other great products. check out "Nymphos Desire".  Corny name but a great product. Strawberry tasting warming cream that wont hurt the privates. Great for DATY and Asian. Doesnt hurt to let her put a little on the boys either.