Macimorelin
Orally active ghrelin (GHSR1a) agonist and growth-hormone secretagogue, FDA-approved as a diagnostic test for adult growth hormone deficiency.
Overview
Macimorelin is a small peptidomimetic mimic of ghrelin that binds the growth-hormone secretagogue receptor type 1a (GHSR1a). Given as a single weight-based oral dose, it produces a robust, transient rise in serum growth hormone (GH) that can distinguish patients with adult GH deficiency (AGHD) from healthy individuals.
Historically, the insulin tolerance test (ITT) was the gold standard for diagnosing AGHD, but it is cumbersome, requires induced hypoglycaemia, and is contraindicated in patients with cardiac disease or seizure disorders. The pivotal phase 3 validation study demonstrated that the oral macimorelin test achieved sensitivity and specificity comparable to the ITT while being far better tolerated (Garcia 2018).
Macimorelin is administered after an overnight fast; GH is sampled at defined intervals (typically 30, 45, 60 and 90 minutes), and a peak GH below the validated cut-off is consistent with GH deficiency. It has also been investigated for diagnosis of childhood-onset GH deficiency and, at repeated doses, explored in cancer cachexia.
Mechanism of Action
As a ghrelin mimetic, macimorelin engages the same G-protein-coupled receptor as endogenous ghrelin, driving Gq/phospholipase-C signalling and calcium-dependent GH release. Because oral bioavailability is sufficient to reach the pituitary, a single oral dose evokes a GH peak in individuals with intact somatotroph function; a blunted peak indicates GH deficiency.
Reconstitution Calculator
Reconstitution Calculator
Calculate your peptide dosing
Set up a clean workspace with all supplies ready.
7x / week for weeks
This calculator is provided for informational and educational purposes only. It is not intended as medical advice, diagnosis, or treatment guidance. Always consult a qualified healthcare professional before preparing or administering any substance. PepGuide assumes no liability for decisions made based on these calculations.
References (2)
- [1]Garcia JM, Biller BMK, Korbonits M, et al. Macimorelin as a Diagnostic Test for Adult GH Deficiency Journal of Clinical Endocrinology & Metabolism (2018)
→ In a phase 3 crossover trial the single oral 0.5 mg/kg macimorelin test showed 92% sensitivity and 96% specificity versus the insulin tolerance test for adult GH deficiency.
- [2]Piccoli F, Degen L, et al. The macimorelin-stimulated growth hormone test for adult growth hormone deficiency diagnosis Expert Review of Endocrinology & Metabolism (2014)
→ Reviews macimorelin as an orally available ghrelin mimetic that acutely raises GH via the GHSR1a receptor with good diagnostic accuracy and a favourable safety profile.
Maca
Maca (Lepidium meyenii/peruvianum) is a root vegetable native to the Peruvian Andes, traditionally used as a dietary supplement for its effects on energy, ferti
Magainin
**Magainins** (magainin 1 and magainin 2) are 23-amino acid cationic antimicrobial peptides originally isolated from the skin of the African clawed frog *Xenopu