Macimorelin
approvedAlso known as: Macrilen, AEZS-130
**Mechanism of Action:** Macimorelin is a synthetic, orally bioavailable ghrelin receptor (GHS-R1a) agonist. It binds to and activates the growth hormone secretagogue receptor in the pituitary and hypothalamus, stimulating endogenous growth hormone (GH) release. Unlike natural ghrelin, macimorelin is resistant to enzymatic degradation and has a longer half-life, enabling oral administration. Its GH-releasing effect is dose-dependent and used diagnostically to assess pituitary GH secretory capacity. **Key Research Findings:** Clinical studies (e.g., NCT01998997, NCT01399749) demonstrated that macimorelin-induced GH stimulation correlates well with the insulin tolerance test (ITT), the gold standard for diagnosing adult growth hormone deficiency (AGHD). A pivotal phase 3 trial (n=154) showed 87% sensitivity and 96% specificity for AGHD diagnosis at a 0.5 mg/kg oral dose, with a safety profile superior to ITT (no hypoglycemia or severe adverse events). Pharmacokinetic data confirm rapid absorption (Tmax ~0.5–1 h) and linear dose-exposure relationships. Macimorelin is approved by the FDA (2017) and EMA (2018) for AGHD diagnosis. **Clinical Relevance:** Macimorelin offers a non-invasive, oral alternative to the insulin tolerance test for AGHD diagnosis, eliminating risks of hypoglycemia and need for intravenous access. It is contraindicated in patients with known hypersensitivity or concurrent use of drugs affecting GH secretion (e.g., glucocorticoids, somatostatin analogs). Its diagnostic use is limited to single-dose administration; therapeutic applications for GH deficiency or aging remain investigational. For research purposes only — not medical advice.
Key data
C26H30N6O3Research & studies
Pediatric panel reached consensus on 17 of 29 (59%) statements; adult panel on 28 of 32 (88%).; Subnormal IGF-I was considered diagnostic for panhypopituitarism in both children and adults.; In children, arginine and glucagon tests were recommended; in adults, ITT was gold standard and macimorelin test was also recommended.; Stimulated GH cut-off <5 μg/L indicated severe GHD in children, while test-specific cut-offs were advised for adults.
Hypertonic saline-stimulated copeptin reliably improves diagnostic accuracy for AVP-D.; Arginine-stimulated copeptin is a simpler alternative test, while glucagon-stimulated copeptin shows promise.; Oral desmopressin formulations have the best tolerance and safety profile for treatment.; Psychopathological factors play an important role in managing AVP-D patients.
Random serum GH measurements are not recommended for screening except in neonates due to episodic GH secretion.; GH stimulation tests may be inaccurate, difficult to perform, and imprecise.; Interpreting test results requires considering patient factors, age-specific cut-offs, testing time points, and assay heterogeneity.; Accurate diagnosis is crucial for appropriate GH replacement therapy, as GHD impacts quality of life and metabolic health.
Frequently asked questions
What is Macimorelin?
**Mechanism of Action:** Macimorelin is a synthetic, orally bioavailable ghrelin receptor (GHS-R1a) agonist. It binds to and activates the growth hormone secretagogue receptor in the pituitary and hypothalamus, stimulating endogenous growth hormone (GH) release. Unlike natural ghrelin, macimorelin is resistant to enzym
How does Macimorelin work?
Orally active ghrelin receptor agonist approved as a diagnostic agent for adult growth hormone deficiency.
What is the research status of Macimorelin?
Macimorelin is currently classified as approved, with 33 research references on record. This is for research purposes only and is not medical advice.
What is the molecular weight of Macimorelin?
Macimorelin has a molecular weight of approximately 474.6 g/mol (formula C26H30N6O3).
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