The present invention relates to derivatives of N-methyl-N-[(1S)-1-phenyl-2-((3S)-3-hydroxypyrrolidin-1-yl)ethyl]-2,2-dip- henylacetamide with covalently bonded acids, and to the salts, solvates and prodrugs thereof, to the derivatives as medicaments, to the use of these derivatives for the preparation of a medicament, to the use of these derivatives for the preparation of a pharmaceutical composition, to a process for the preparation of the said pharmaceutical compositions, to pharmaceutical compositions obtainable by this process, and to a process for the treatment of diseases which comprises the administration of the said pharmaceutical composition.