I can't find any reference to bepanthol being for sale in the US - only in Europe.
However, my mom has been on Tarceva for 6 months. For the dry skin and rash we had her bathe and lotion with Lindiskin and it is great for overcoming the dry skin. You can get it at www.lindiskin.com
I guess sound like an advertisement for it - but gee - it works so good. Mom is so happy with it!
Also try Biotene mouthwash - can get at Walmart or almost any drug store for the dry mouth associated with Tarceva.