Lenomorelin (Ghrelin) is a pleiotropic hormone, whose effect on growth hormone secretion, through the growth hormone secretagogue (GHS) receptor, is one of its many actions. It is synthesized principally in the stomach. Ghrelin-producing cells constitute a distinct group of endocrine cells dispersed throughout the gastric mucosa and to a lesser extent in the small intestine and the endocrine pancreas. Ghrelin plasma levels rise during fasting and chronic caloric restriction to stimulate food intake and fat storage and to prevent life-threatening falls in blood glucose. Plasma ghrelin levels decrease after a meal is consumed and in conditions of energy surplus (such as obesity). Ghrelin has emerged as a key player in the regulation of appetite and energy homeostasis. It stimulates food intake and transduces signals to hypothalamic regulatory nuclei that control energy homeostasis. Ghrelin levels are negatively correlated with body mass index (BMI) and insulin resistance. Lenomorelin is a peptide of 28 amino acids, in which the serine 3 residue is n-octanoylated, which is necessary for biological activity.

Rusalatide acetate (also known as chrysalin or TP 508) is a 23-amino acid peptide derived from human prothrombin; it represents part of the receptor-binding domain of the human thrombin molecule. Rusalatide acetate binds to high-affinity thrombin receptors and mimics cellular effects of thrombin at sites of tissue injury. Rusalatide acetate demonstrated safety and potential efficacy in phase I/II clinical trials for the treatment of diabetic foot ulcers. It interacts with cell surface receptors to stimulate a cascade of cellular and molecular wound healing events, including activation of nitric oxide signaling. In addition, this drug participated in phase II clinical trial to determine the effectiveness of four doses for treating broken wrists in adults. However, this study was terminated because the drug did not demonstrate benefit compared to placebo. Rusalatide acetate was also studied as a cardiovascular drug. However, in January 2012, Capstone discontinued the development of rusalatide, for financial reasons. Recent studies show that a single injection of TP508 (rusalatide acetate) administered 24 h after irradiation significantly increases survival and delays mortality in murine models of acute radiation mortality. Thus, this drug is being developed as a potential nuclear countermeasure.

Angiotensin III (Ang III) is a bioactive heptapeptide that is formed from the degradation of the Angiotensin II peptide by aminopeptidase A. In peripheral Angiotensin systems, Angiotensin II is the main effector peptide in the systemic circulation, although exogenous Angiotensin III can be as potent as Angiotensin II in, for example, stimulating aldosterone secretion or inhibiting renin release. In the rat brain, Angiotensin III was found to be equipotent with Angiotensin II as a pressor agent or dipsogen and was bound as avidly to the nervous system as Angiotensin II. Angiotensin receptor subtype AT1 has the greater affinity towards Angiotensin II and is also responsive to Angiotensin III, while the AT2 receptor subtype appears to be more sensitive to Angiotensin III but less responsive to Angiotensin II. Angiotensin III enhances blood pressure, vasopressin release and thirst when it is centrally administrated. Angiotensin III infusion increases blood pressure in healthy volunteers and hypertensive patients as well as augments aldosterone release. Although Angiotensin III does not change renal function in humans, it induces natriuresis in AT, receptor-blocked rats likely by binding to AT2 receptors. In addition, in cultured renal cells, this peptide stimulates the expression of many growth factors, proinflammatory mediators, and extracellular matrix proteins.

Peginesatide (trade name Omontys, formerly Hematide), developed by Affymax and Takeda, is an erythropoietic agent, a functional analog of erythropoietin. It was approved by the U.S. Food and Drug Administration for treatment of anemia associated with chronic kidney disease (CKD) in adult patients on dialysis. Peginesatide is a synthetic peptide, attached to polyethylene glycol ("PEGylated"). It mimics the structure of erythropoietin, the human glycoprotein which promotes red blood cell development. Peginesatide binds to and activates the human erythropoietin receptor and stimulates erythropoiesis in human red cell precursors in vitro.

Sermorelin, a 29 amino acid analog of human growth hormone-releasing hormone (GHRH), is the shortest synthetic peptide with a full biological activity of GHRH which is used as a diagnostic agent to assess growth hormone (GH) secretion for the purpose of diagnosing growth hormone deficiency. Intravenous and subcutaneous sermorelin specifically stimulate growth hormone secretion from the anterior pituitary. Sermorelin binds to the growth hormone releasing hormone receptor and mimics native GRF in its ability to stimulate growth hormone secretion. Hormone responses to intravenous sermorelin appear to be a rapid and relatively specific test for the diagnosis of growth hormone deficiency.