The single ionization of multielectron atoms by the impact of protons, anti
protons, and highly charged bare ions is studied. The targets are treated a
s one-electron atoms, where the interaction of the active electron with the
rest of the target is represented by a model potential. The final electron
ic state is described by the product of two Coulomb wave functions that put
the distortion due to the projectile and the target on equal footing. We c
alculate the total and differential ionization cross sections for helium- a
nd lithium-atom targets. The results thus obtained are compared with existi
ng experimental data and other available theoretical predictions.