Capromorelin

Growth Hormone Axis

Also known as: Entyce, AT-002, Capromorelin Tartrate, CP-424,391

Growth Hormone Secretagogues (Oral)Research phase: Phase II (human), FDA-approved (veterinary)Regulatory: FDA-approved for veterinary use (Entyce, appetite stimulation in dogs). Not approved for human use. Phase II trials showed efficacy in elderly but human development discontinued. Available as research compound.

Mechanism

Capromorelin is an oral ghrelin receptor agonist that stimulates both growth hormone release and appetite. It is notable for being the first GHS-R agonist to receive regulatory approval — though for veterinary use: it is FDA-approved as Entyce for appetite stimulation in dogs. In human clinical trials, it significantly increased GH levels, lean body mass, and functional performance in elderly subjects, but was not pursued further for human approval. It represents proof-of-concept that oral ghrelin agonists can safely boost GH in humans.

Technical detail

Capromorelin is a non-peptide, orally bioavailable growth hormone secretagogue receptor (GHS-R1a) agonist. Binds the ghrelin receptor with high affinity, mimicking endogenous ghrelin's effects on the hypothalamic-pituitary axis. Mechanism: GHS-R1a activation on pituitary somatotrophs → Gq/PLC/IP3 → intracellular calcium mobilization → GH exocytosis. Also activates hypothalamic GHRH neurons and suppresses somatostatin release. Orally bioavailable (human F ~60-70%). In a 12-month Phase II RCT in elderly subjects (65+ years): significantly increased GH secretion (2-3 fold), lean body mass (+1.4 kg), tandem walk performance, and stair climb power vs. placebo (White et al., JCEM 2009, PMID: 19567522). Appetite stimulation via vagal afferent activation and hypothalamic NPY/AgRP pathway. Veterinary approval: FDA-approved as Entyce (Aratana Therapeutics/Elanco) for inappetence in dogs.

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