The present invention relates to compounds of formula (1), in which H, G, Z, X, Y, r, s and t have the meanings indicated in the claims, their physiologically tolerable salts and their prodrugs. The compounds of formula (1) are valuable, pharmacologically active compounds. They are vitronectin receptor antagonists and inhibitors of cell adhesion and are suitable for the therapy and prophylaxis of illnesses which are based on the interaction between vitronectin receptors and their ligands in cell-cell or cell-matrix interaction processes or which can be prevented, alleviated or cured by influencing such interactions. For example, they can be applied for inhibiting bone resorption by osteoclasts and thus for treating and preventing osteoporosis, or for inhibiting undesired angiogenesis or proliferation of cells of the vascular smooth musculature. The invention furthermore relates to processes for the preparation of compounds of formula (1), their use, in particular as active ingredients in pharmaceuticals, and pharmaceutical compositions comprising them.