Production of an injectable pharmaceutical composition comprises dissolving a drug derivative (I) in an injectable carrier liquid, where (I) comprises a drug linked to a protein-binding group via a spacer and where the spacer or the linkage between the drug and the spacer is pH-dependently or enzymatically cleavable in vivo to release the drug. An independent claim is also included for a drug derivative of type (I) in which the drug is not a cytostatic agent.