With the discovery of an increasing number of biologically active peptides and peptide mimetics (1 –3 ), there is a pressing need for the development of strategies to deliver these biologically active compounds to the desired site of action. The preceding two chapters have described two methods of making esterase-sensitive cyclic prodrugs of peptides. In this chapter, we wish to describe a third method of making esterase-sensitive cyclic prodrugs of peptides using DADLE, an opioid peptide (4 –7 ), as an example.
