Peptides Studied for Injury Recovery

Calcitonin (salmon) is a synthetic 32-amino-acid peptide hormone (MW ~3431.9 g/mol) identical to calcitonin produced by the ultimobranchial glands of salmon. It is FDA-approved for the treatment of postmenopausal osteoporosis (nasal spray), hypercalcemia of malignancy (injection), and Paget disease of bone (injection). Salmon calcitonin is approximately 40-50 times more potent than human calcitonin at inhibiting osteoclast activity. It is no longer a first-line therapy for osteoporosis due to the availability of more effective agents and a potential cancer risk signal.

Terlipressin is a synthetic vasopressin analog (MW ~1227.4 g/mol) that acts as a prodrug, slowly converted by tissue peptidases to the active metabolite lysine vasopressin. It was FDA-approved in September 2022 (Terlivaz) for hepatorenal syndrome type 1 (HRS-1), making it the first pharmacotherapy specifically approved for this indication in the United States. Terlipressin has been used in Europe for decades for variceal bleeding and hepatorenal syndrome. It acts primarily via V1a receptors to cause splanchnic vasoconstriction, improving renal perfusion in the context of portal hypertension.

Degarelix is a synthetic GnRH antagonist (MW ~1632.3 g/mol) and the first injectable GnRH receptor blocker approved for advanced prostate cancer. FDA-approved in 2008 (Firmagon), it produces immediate suppression of LH, FSH, and testosterone without the initial hormonal flare seen with GnRH agonists. This is clinically significant in patients where testosterone flare could cause complications such as spinal cord compression, urinary obstruction, or bone pain exacerbation. Degarelix is administered as a monthly subcutaneous injection.

Human growth hormone (hGH, somatotropin) is a 191-amino acid protein produced by the anterior pituitary gland. Recombinant human growth hormone (rhGH, somatropin) is FDA-approved for numerous indications including pediatric and adult growth hormone deficiency, Turner syndrome, short stature from small for gestational age (SGA), Prader-Willi syndrome, chronic kidney disease, idiopathic short stature, and short bowel syndrome (Zorbtive). It is one of the most extensively studied hormones in medicine. Off-label use for anti-aging and performance enhancement is widespread but not approved, and GH is banned by WADA in sport.

Insulin-like Growth Factor 1 (IGF-1) is a 70-amino acid protein structurally similar to insulin. It is primarily produced by the liver in response to growth hormone stimulation and mediates many of GH's growth-promoting effects. Recombinant human IGF-1 (mecasermin, brand name Increlex) is FDA-approved for the treatment of severe primary IGF-1 deficiency (primary IGFD) — a condition where patients have normal or elevated GH but fail to produce adequate IGF-1. IGF-1 plays critical roles in growth, development, and metabolism throughout life. It circulates bound to IGF binding proteins (primarily IGFBP-3 in a ternary complex with acid-labile subunit).

Teduglutide is a 33-amino-acid recombinant analog of human glucagon-like peptide-2 (GLP-2) (MW ~3752 g/mol) with a single amino acid substitution (Ala2 to Gly) that confers resistance to dipeptidyl peptidase-4 (DPP-4) degradation. It was FDA-approved in December 2012 (brand name Gattex in the US, Revestive in Europe) for the treatment of adults with short bowel syndrome (SBS) who are dependent on parenteral support. Teduglutide is the first and only GLP-2 analog approved for this indication.

Plecanatide is a 16-amino-acid synthetic peptide (MW ~1681.9 g/mol) that is a structural analog of uroguanylin, an endogenous intestinal peptide. It was FDA-approved in January 2017 for chronic idiopathic constipation (CIC) and in January 2018 for irritable bowel syndrome with constipation (IBS-C) in adults. Plecanatide acts locally in the intestinal lumen with minimal systemic absorption, functioning as a guanylate cyclase-C (GC-C) agonist to increase intestinal fluid secretion.

Linaclotide is a 14-amino-acid synthetic peptide (MW ~1526.8 g/mol) structurally related to the endogenous guanylin and uroguanylin peptides, containing three intramolecular disulfide bonds. It was FDA-approved in August 2012 for irritable bowel syndrome with constipation (IBS-C) in adults and chronic idiopathic constipation (CIC) in adults. Linaclotide is a guanylate cyclase-C (GC-C) agonist that acts locally in the intestinal lumen with minimal systemic absorption, increasing intestinal fluid secretion and reducing visceral pain signaling.

Abaloparatide is a 34-amino-acid synthetic peptide analog of parathyroid hormone-related protein (PTHrP) (MW ~3960.6 g/mol), FDA-approved in April 2017 for the treatment of postmenopausal women with osteoporosis at high risk for fracture. It selectively activates the PTH1 receptor in its RG (guanine nucleotide-free) conformation, which favors anabolic bone-forming activity over bone resorption. Abaloparatide represents a differentiated approach from teriparatide, with potentially less bone resorption stimulation and lower hypercalcemia risk.

Teriparatide is the recombinant form of the first 34 amino acids of human parathyroid hormone (PTH(1-34), MW ~4117.8 g/mol), FDA-approved in November 2002 as the first anabolic agent for osteoporosis treatment. It is indicated for postmenopausal women and men at high risk for fracture, as well as glucocorticoid-induced osteoporosis. Teriparatide works by stimulating new bone formation rather than merely slowing bone loss, representing a paradigm shift in osteoporosis treatment when introduced.

Calcitonin salmon (also known as salcatonin) is a synthetic 32-amino-acid peptide (MW ~3431.9 g/mol) identical to calcitonin produced by the ultimobranchial glands of salmon. It is approximately 40-50 times more potent than human calcitonin in inhibiting osteoclast-mediated bone resorption. It is FDA-approved as a nasal spray (Miacalcin, Fortical) for postmenopausal osteoporosis, and as an injection for Paget disease of bone, hypercalcemia of malignancy, and osteoporosis. Calcitonin salmon is now considered a second- or third-line osteoporosis therapy due to modest efficacy compared to newer agents.

PTH (parathyroid hormone) is the full-length 84-amino-acid recombinant human parathyroid hormone (MW ~9425 g/mol) marketed as Natpara. It was FDA-approved in January 2015 as an adjunct to calcium and vitamin D for the control of hypocalcemia in patients with hypoparathyroidism, making it the first FDA-approved PTH replacement therapy. Natpara is available only through a restricted Risk Evaluation and Mitigation Strategy (REMS) program due to a potential risk of osteosarcoma observed in animal studies.

HGH 191AA refers to recombinant human growth hormone (somatropin) — a 191-amino acid, single-chain polypeptide (MW ~22,124 g/mol) identical in sequence to endogenous pituitary growth hormone. It is FDA-approved for growth hormone deficiency in children and adults, Turner syndrome, chronic renal insufficiency, Prader-Willi syndrome, and HIV-associated wasting. In the peptide community, "191AA" distinguishes legitimate somatropin from the older 192-amino acid variant (somatrem, which had an extra methionine and higher immunogenicity).

Somatropin is recombinant human growth hormone (rHGH), a 191-amino-acid protein identical to naturally produced pituitary GH. Unlike secretagogues (which stimulate GH release), somatropin IS the direct hormone. FDA-approved for multiple indications including growth hormone deficiency, Turner syndrome, and chronic renal insufficiency in children.

Human Menopausal Gonadotropin (HMG) is a purified hormonal preparation containing both follicle-stimulating hormone (FSH) and luteinizing hormone (LH) in approximately equal ratios. Originally extracted from the urine of postmenopausal women, modern preparations (e.g., Menopur) use highly purified or recombinant forms. HMG is a cornerstone of fertility medicine, used for controlled ovarian stimulation in IVF and treatment of hypogonadotropic hypogonadism. In the performance enhancement community, it is used for post-cycle therapy and testicular recovery.

Thymosin beta-4 (Tβ4) is a naturally occurring 43-amino acid protein found in virtually all human and animal cells. It is the most abundant member of the beta-thymosin family and plays fundamental roles in cell migration, wound healing, and tissue repair. Tβ4 is distinct from TB-500, which is a synthetic peptide containing only the active heptapeptide region (Ac-LKKTETQ) of Tβ4. The full-length protein is being developed as RGN-259 (RegeneRx Biopharmaceuticals) eye drops for dry eye, neurotrophic keratopathy, and other ophthalmic conditions, with multiple Phase II/III clinical trials completed or ongoing.

Larazotide (AT-1001) is a synthetic 8-amino acid peptide that acts as a tight junction regulator. It is being developed as an oral adjunct therapy for celiac disease, designed to reduce intestinal permeability ("leaky gut") triggered by gluten exposure. It is the first drug in its class and has completed Phase II clinical trials and a Phase III trial (INN-202, also called CeDLara). Larazotide works locally in the gut lumen without significant systemic absorption. It was originally developed by Alba Therapeutics and later acquired by Innovate Biopharmaceuticals (now 9 Meters Biopharma).

B-type natriuretic peptide (BNP) is a 32-amino-acid cardiac hormone (MW ~3464 g/mol) secreted primarily by ventricular cardiomyocytes in response to myocardial wall stress from volume overload or pressure overload. It is both a critical diagnostic biomarker for heart failure (BNP/NT-proBNP assays) and the basis for the therapeutic agent nesiritide (recombinant BNP). Originally identified in porcine brain tissue, hence the historical name "brain natriuretic peptide."

Ghrelin is a 28-amino acid peptide hormone produced primarily by the stomach that serves as the endogenous ligand for the growth hormone secretagogue receptor (GHS-R1a). It is the only known circulating orexigenic (appetite-stimulating) hormone. Ghrelin stimulates growth hormone release, increases appetite, promotes fat storage, and coordinates energy metabolism between the gut and brain. It requires a unique post-translational modification (n-octanoylation at Ser3) for biological activity. Pharmaceutical analogs like anamorelin have been developed for cancer-related cachexia.

BPC-157 is a synthetic 15-amino-acid peptide (sequence: Gly-Glu-Pro-Pro-Pro-Gly-Lys-Pro-Ala-Asp-Asp-Ala-Gly-Leu-Val, MW ~1419.5 g/mol) derived from a protein found in human gastric juice. It has demonstrated robust regenerative and cytoprotective effects across hundreds of animal studies spanning tendon, ligament, muscle, bone, nerve, GI tract, and blood vessel healing. However, human clinical data is extremely limited — only three pilot studies have examined BPC-157 in humans as of 2025 (knee pain n=16, interstitial cystitis n=12, IV safety n=2). The FDA classifies it as Category 2, prohibiting compounding, and WADA bans its use in sports.