Linaclotide (marketed under the trade name Linzess and Constella) is a peptide agonist of the guanylate cyclase 2C (GC-C). Once linaclotide and its active metabolite binds to GC-C, it has local effect on the luminal surface of the intestinal epithelium. Activation of GC-C by linaclotide results in the intra- and extracellular increase of cyclic guanosine monophosphate concentrations (cGMP). This elevation of cGMP levels stimulates the secretion of chloride and bicarbonate into the intestinal lumen via activation of cystic fibrosis transmembrane conductance regulator (CFTR) ion channel. The metabolite of linaclotide MM-419447 (CCEYCCNPACTGC) contributes to the pharmacologic effects of linaclotide. Ultimately, linaclotide helps patients with IBS (especially with constipation) as GI transit is accelerated and the release of intestinal fluid is increased. In animal models, a decrease in visceral pain after administration of linaclotide may be observed. A decrease in the activity of pain-sensing nerves occurs as a result of an increase in extracellular cGMP. It was approved by the FDA in August 2012 for the treatment of chronic idiopathic constipation and irritable bowel syndrome with constipation (IBS-C) in adults.

Tesamorelin is an analog of human growth hormone-releasing factor (GRF). The peptide precursor of tesamorelin acetate is produced synthetically and is comprised of the 44 amino acid sequence of human GRF. In vitro, tesamorelin binds and stimulates human GRF receptors with similar potency as the endogenous GRF. GRF, also known as growth hormone-releasing hormone (GHRH), is a hypothalamic peptide that acts on the pituitary somatotroph cells to stimulate the synthesis and pulsatile release of endogenous growth hormone (GH), which is both anabolic and lipolytic. GH exerts its effects by interacting with specific receptors on a variety of target cells, including chondrocytes, osteoblasts, myocytes, hepatocytes, and adipocytes, resulting in a host of pharmacodynamic effects. Some, but not all these effects, are primarily mediated by IGF-1 produced in the liver and in peripheral tissues. Tesamorelin is the first and, so far, only treatment indicated for the reduction of excess abdominal fat in patients with HIV-associated lipodystrophy. Tesamorelin is effective in improving visceral adiposity and body image in patients with HIV-associated lipodystrophy over 26-52 weeks of treatment. Potential limitations for its use include high cost and lack of long-term safety and adherence data. Tesamorelin provides a useful treatment option for management of patients with significant lipodystrophy related to HIV infection.

Lanreotide is a medication used in the management of acromegaly and symptoms caused by neuroendocrine tumors, most notably carcinoid syndrome. It is a long-acting analog of somatostatin. It is available in several countries, including the United Kingdom, Australia and Canada, and was approved for sale in the United States by the Food and Drug Administration on August 30, 2007. Lanreotide was developed in the lab of Dr. David H. Coy, School of Medicine. Dr. Coy serves as Director of the Peptide Laboratory. Lanreotide (as lanreotide acetate) is manufactured by Ipsen, and marketed under the trade name Somatuline. The mechanism of action of lanreotide is believed to be similar to that of natural somatostatin. Lanreotide has a high affinity for human somatostatin receptors (SSTR) 2 and 5 and a reduced binding affinity for human SSTR1, 3, and 4. Activity at human SSTR 2 and 5 is the primary mechanism believed responsible for GH inhibition. Like somatostatin, lanreotide is an inhibitor of various endocrine, neuroendocrine, exocrine and paracrine functions. Lanreotide inhibits the basal secretion of motilin, gastric inhibitory peptide and pancreatic polypeptide, but has no significant effect on the secretion of secretin. Lanreotide inhibits postprandial secretion of pancreatic polypeptide, gastrin and cholecystokinin (CCK). In healthy subjects, lanreotide produces a reduction and a delay in post-prandial insulin secretion, resulting in transient, mild glucose intolerance.

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.

Forigerimod (also known as IPP-201101) a phosphopeptide is being investigated for the treatment of Lupus Erythematosus, Systemic. This drug is completed phase III clinical trials and is ready for licensing.

Dirucotide (MBP 8298) is a synthetic myelin basic protein (MBP) peptide designed to decrease type 2 helper T cells (TH2)-mediated B-cell signalling of auto-reactive T-cells thereby reducing the production of specific antibodies that target endogenous MBP. MBP is the dominant site of attack in patients with multiple sclerosis and haplotype (HLA) DR2 or DR4. Dirucotide did not meet the primary endpoint of delaying disease progression, as measured by the Expanded Disability Status Scale (EDSS), during the two-year MAESTRO-01 Phase III trial in patients with secondary progressive multiple sclerosis (SPMS). In addition, there were no statistically significant differences between dirucotide and placebo on the secondary endpoints of the study. After disappointing trial results, development of the drug was ended in 2009.