Peptides are small proteins that play an important role in the body, but they cannot be taken orally like other proteins because they are broken down by enzymes in the digestive system. This is why peptides must be injected, either under the skin or into a muscle. By bypassing the digestive system, peptides can reach their target cells and tissues more quickly and effectively. In addition, some peptides have a short half-life and are destroyed by enzymes in the stomach if taken orally. By injecting them, we can ensure that they reach their targets intact and have the desired effect.