Provided herein are methods to generate and screen peptides that exhibit drug like stabilities in vitro and in vivo. By selecting for enzyme resistance, Applicants are able to derive peptides that are not only stable to a broad spectrum of proteases, but also stable to other drug processing enzymes such as cytochrome P450s. This approach provides a general method to the rapid development of highly stable peptides for therapeutic development and diagnosis. The peptides are further modified for oral bioavailability. The methods can be applied to similar peptides for the making of therapeutic compositions.
