Semparatide (previously known as RS-66271) was developed as an analog of parathyroid hormone-related protein (PTHrP) with shortening the time for fracture healing. Experiments on animals have shown that this compound was an effective therapy for preventing impaired bone healing caused by prednisone. Clinical trials with postmenopausal osteoporotic women have revealed that semparatide cause sustained increases in the spine. However, further, development appears to have been discontinued by Roche.

Metenkephalin (Met-enkephalin) is an endogenous opioid peptide that acts as an agonist at μ-opioid receptors (μORs) and δ-opioid receptors (δORs). Met-enkephalin exhibits neuromodulatory, antinociceptive/analgesic, antidepressant, and gastrointestinal motility modulating activities. Like other endogenous opioids, met-enkephalin modulates expression of opioid receptors and plays a role in reward/reinforcement signaling. Met-enkephalin is also involved in exercise-induced reversal of neuropathic pain and in animals undergoing the forced swim test, decreases immobility time. Met-enkephalin inhibits gastrointestinal muscle contractility, inhibiting motility and gastric emptying. Additionally, analogs of this peptide display anticancer and antiepileptic/anticonvulsant activities.

Pexiganan is a 22-amino-acid synthetic cationic peptide. It is an analog of magainin 2, which is a host defense peptide isolated from frog skin. The drug is thought to act by disturbing the permeability of the cell membrane or cell wall. Pexiganan exhibited in vitro broad-spectrum antibacterial activity when it was tested against 3,109 clinical isolates of gram-positive and gram-negative, anaerobic and aerobic bacteria. It is currently in phase 3 clinical trials as a topical antimicrobial agent for the treatment of mild infections associated with diabetic foot ulcers. In vitro data for pexiganan acetate suggest that the drug does have hemolytic activity at concentrations relevant for antibacterial activity. In association with tigecycline, pexiganan administration could overcome antibiotic resistance and increase the effectiveness of treatment against P. aeruginosa sepsis.

Ozarelix is a luteinizing hormone-releasing hormone (LHRH) antagonist. It is known that LHRH antagonist exerts rapid inhibition of luteinizing hormone and follicle stimulating hormone with an accompanying rapid decrease in sex hormones. Thus this inhibitor can be effective in a variety of hormonally dependent disease including prostate cancer, benign prostatic hyperplasia (BPH), and endometriosis. Ozarelix was developed for the treatment of all these diseases including Alzheimer's disease. However, in January 2010 Spectrum Pharmaceuticals announced that it was discontinuing development of ozarelix in BPH. Because the low-dose intermittent therapy was disappointing in the treatment of lower urinary tract symptoms in men with BPH. The development of the drug for Alzheimer's disease was also discontinued. Ozarelix completed phase II trials for the treatment of prostate cancer and is in preclinical trials for the treatment of endometriosis and ovarian cancer.

Lutrelin is an agonist of gonadotropin-releasing hormone receptor exerting antineoplastic properties.

Detirelix is a synthetic decapeptide containing five D-amino acids. It is a very potent Gonadotropin-releasing hormone (GnHR) antagonist. The acute effects of detirelix were consistent with peripheral vasodilation. Subchronic effects were associated with inhibition of pituitary gonadotropic and gonadal hormone secretion. As long-acting GnRH antagonist detirelix can rapidly suppress gonadotropin secretion, inhibit follicular development, and prevent ovulation. It can be used as luteolytic agent. A projected use is for the treatment of sex hormone-releasing diseases, as part of anticancer hormone therapy of sex-hormone-dependent tumors.

Delmitide is the decapeptide with antiinflammatory activity. It is the first low molecular weight compound inhibiting TNF production at a translational level. Also, delmitide inhibits production of IFN-gamma, IL-12 and IL-2. It targets TRAF6/IRAK4/MyD88 complex and inhibits phosphorylation of SAPKs (p38 and JNK). Delmitide inhibits AP1 and NFkB activation. Delmitide was developed for the potential treatment of Crohn's disease and ulcerative colitis; phase II trials for both these indications commenced in October 2001. Phase I trial in chemotherapy-induced diarrhea and the gastrointestinal complications of HIV were also initiated. However, no recent development has been reported.

Prazarelix is gonadorelin (GnRH) antagonist. It is primarily used in assisted reproduction to control ovulation. The drug works by blocking the action of GnRH upon the pituitary, thus rapidly suppressing the production and action of luteinizing hormone (LH) and follicle-stimulating hormone (FSH).