Specific GLP-1 receptor agonists
The development of the GLP-1 receptor agonists is based on two different approaches. One strategy exploits the structure of native human GLP-1, modified in a way so that it is resistant to degradation by DPP-4, as the backbone for the compounds. The other approach uses a natural occurring protein - exendin-4, originally isolated from the saliva of the lizard Heloderma Suspectum - as the backbone of the compounds. Exendin-4 has a 53% sequence homology with human GLP-1 in its first 30 amino acids, and binds to and activates the GLP-1R with equal potency as native GLP-1. Of today, three GLP-1 receptor agonists have been approved for the treatment of type 2 diabetes: exenatide twice-daily (Byetta®, Amylin/Lilly)/exenatide once-weekly (Bydureon®, Amylin/Lilly) based on exendin-4, and liraglutide (Victoza®, Novo Nordisk), based on the structure of native GLP-1, for once-daily subcutaneous injection.