Corticotropin-releasing hormone (CRH) is a 41-amino-acid peptide, derived from a 196-amino-acid preprohormone and secreted by the paraventricular nucleus of the hypothalamus. It sits at the apex of the hypothalamic-pituitary-adrenal (HPA) axis: released into the portal circulation in response to stress, it stimulates pituitary corticotropes to secrete adrenocorticotropic hormone (ACTH), and ACTH in turn drives cortisol synthesis. The chain from hypothalamic CRH to pituitary ACTH to adrenal cortisol is one of the most thoroughly characterised peptide signalling systems in human physiology.
The peptide is also known as corticotropin-releasing factor (CRF), or corticoliberin. The names are used interchangeably in the literature; CRH is the more common form in clinical writing.
What corticorelin is
Corticorelin is the international non-proprietary name for the synthetic form of human CRH (hCRH). Two distinct uses appear in the record.
The first is diagnostic. A corticorelin stimulation test measures plasma ACTH and cortisol after the synthetic peptide is given, and is used to separate an ACTH-dependent hypercortisolism of pituitary origin (a response is seen) from ectopic ACTH secretion (little or no response). It sits alongside the other dynamic tests of the axis, including the dexamethasone suppression test and the ACTH stimulation test, for which the synthetic ACTH fragment tetracosactide is used.
The second is therapeutic, and it did not reach a licence. Corticorelin acetate was developed for peritumoral brain oedema — the swelling that surrounds a tumour in the brain. The rationale was steroid-sparing: dexamethasone is effective but its systemic effects can be dose-limiting and can warrant discontinuation, and a targeted CRH-based approach was proposed as an alternative. The programme's clinical development was concentrated in the United States, under the trade name Xerecept. No UK marketing authorisation for corticorelin is identified.
The class boundary: peptides and non-peptides
CRH signalling is one of the clearest places where the peptide and small-molecule worlds meet, and the distinction matters when reading the literature. CRH itself is a peptide, as are the related CRF-family ligands: the urocortins (UCN1, UCN2 and UCN3), frog-skin sauvagine, and fish urotensin. The compounds developed to block CRH signalling — the CRF1 receptor antagonists such as antalarmin and pexacerfont — are small molecules, not peptides, and have been studied chiefly in psychiatry, including depression and alcohol use disorder, rather than as peptide medicines.
The receptor side completes the picture: CRH acts through two G-protein-coupled receptors, CRHR1 and CRHR2, with the urocortins supplying the second receptor's preferred ligands.
UK regulatory position
Corticorelin holds no marketing authorisation in the UK, and CRH itself is not a licensed medicine. Any UK supply would fall to be assessed under the Medicines Act 1968 and the Human Medicines Regulations 2012, with the MHRA applying its case-by-case test for whether a product is a medicinal product. A compound offered 'for research' does not escape that test where it is in fact being made available for human use.
This article describes the research and regulatory record only. CRH and corticorelin are not for human consumption, and nothing here is usage, dosing or administration guidance.
Evidence grade
As a physiological system, the CRH axis is among the best characterised in endocrinology. As a research compound for human use outside licensed practice, corticorelin has a narrow, dated record: one diagnostic application, a therapeutic programme that did not reach approval, and no controlled human trial evidence for any other use. The most detailed reviews of the brain-oedema programme date from 2009 and 2010. That ceiling is stated here rather than implied.
This article is AI-researched and editorially reviewed. It is provided for research and educational purposes only and is not medical advice. Research peptides are not licensed for human consumption in the UK.