What it is
ACTH is a hormone of 39 amino acids made by the pituitary gland, at the base of the brain. UniProt's record (P01189) gives the human sequence — SYSMEHFRWGKPVGKKRRPVKVYPNGAEDESAEAFPLEF — a straight chain with no sulfur bridges. Its other name, corticotropin, means "acting on the adrenal cortex", which is exactly what it does.
It does not have a gene of its own. It is cut from pro-opiomelanocortin (POMC), a 267-residue precursor that carries several hormones:
| Piece of POMC | Residues | What it is |
|---|---|---|
| ACTH | 138–176 | Drives cortisol from the adrenal glands |
| Alpha-MSH | 138–150 | ACTH's first 13 residues, amidated; skin pigment and appetite signals |
| Beta-endorphin | 237–267 | An endogenous opioid |
That shared origin is why the tanning peptides in this library — melanotan-1 and melanotan-2, copies of alpha-MSH — sit in the same family as a stress hormone.
What it does
ACTH binds the melanocortin-2 receptor (MC2R), found mainly in the adrenal cortex (UniProt Q01718). The adrenal glands respond by making cortisol. UniProt's annotation of the receptor describes it coupling to G(s) and the cAMP pathway, leading to steroid production.
The Cortrosyn label adds a finding about where the activity sits: residues 1–20 are the minimal sequence with full activity, and shortening from 20 to 19 loses 70% of potency. The back half of the molecule, residues 22–39, carries most of its immunological activity — what antibodies recognise.
The medicines
| Product | What it is | Approved | Labelled use |
|---|---|---|---|
| Acthar Gel (Mallinckrodt) | Porcine pituitary mixture; major component N-25 deamidated porcine ACTH(1-39), in 16% gelatin | 1952-04-29 (NDA008372) | Infantile spasms under age 2; MS flares; adjunctive use in rheumatic, skin, eye and other inflammatory disorders |
| Purified Cortrophin Gel (ANI) | Porcine ACTH(1-39), 80 USP units/mL in 15% gelatin | 1954-06-16 (NDA008975) | Rheumatic, collagen, skin, allergic, eye, respiratory and oedematous disorders |
| Cortrosyn (cosyntropin) | Synthetic ACTH(1-24), 0.25 mg vials | 1970-04-22 (NDA016750) | Diagnostic only: screening for adrenal insufficiency |
The Acthar label states its own limit on multiple sclerosis: controlled trials showed it speeds the resolution of acute flares, but there is "no evidence that it affects the ultimate outcome or natural history of the disease."
Where it stands
All three are listed with current prescription presentations, and Sandoz holds a generic cosyntropin (ANDA202147, 2012) (openFDA, 2026-10-03). PubMed returns 55,946 records for "adrenocorticotropic hormone", 1,086 tagged as randomised controlled trials.
Related reading
ACTH sits among the other pituitary and hypothalamic peptides in this library — vasopressin, gonadorelin and sermorelin. Some growth-hormone releasers nudge cortisol as well; the entry on the growth-hormone releaser GHRP-6 records that ipamorelin was designed to do so less.