[en] Widths for the transition (panti p)sub(atomic) → (Nanti N)sub(B)+π between initial 1s states and final T = 0, S = 1 natural parity states have been computed within a non-relativistic perturbative model that combines the impulse approximation with p-wave and s-wave pion rescattering terms. The final states are treated as quasi-nuclear Nanti N states bound in a 2-body potential obtained from the Paris NN interaction via G-parity transformation and introduction of a cut-off radius. In the initial atomic states both annihilation and isospin mixing effects are included. The results indicate that annihilation effects in the initial states, through the suppression of short-range components in the wave functions, are extremely important in diminishing rescattering contributions to the transitions and stabilizing the binding energy dependence of the widths. Without annihilation, the calculated widths are unreasonably large and dominated by the rescattering terms. The effects of shorter-range contributions such as multiple rescattering and meson-baryon form factors has also been investigated and found to be unimportant when annihilation effects are included. (orig.)