Recently a derivation of the diffusion coefficient of highly energetic protons in nuclei has been published. The derivation, based on Glauber's theory, was lacking a formal and general framework which could provide for a sound description of the dynamic behaviour of the incoming proton. The authors derive general expressions for the kinetic coefficients in high energy ( approximately 1 GeV) proton-nucleus collisions. Analytical expressions for these coefficients in nuclear matter are given and Pauli blocking effects are shown to be quantitatively very important. They also show that the Fokker-Planck equation is a limit of the theory, and can be solved analytically. Results are compared with the previous ones obtained in the context of Glauber's theory.