The invention relates to compounds which, acting as a prodrug and/or support, enable an active agent to be taken up by the erythrocytes and/or an active agent to bind to the erythrocytes. The uptake of these compounds by and/or the binding thereof to the erythrocytes is made possible by a group of formula --SO2NR1R2, wherein R1 and R2, independently of each other, mean a hydrogen atom, an acyl group, an alkyl group, a cycloalkyl group, an aryl group, a cyano group or a hydroxy group. The inventive prodrugs enable active agents such as endogenic substances, natural substances and synthetic substances with therapeutically useful properties which have a high "first path" effect, to be administered orally effectively or significantly improve the oral activity thereof.