Capromorelin: Oral Ghrelin Receptor Agonist — Veterinary Approved, Not for Human Use

Capromorelin is a synthetic, orally bioavailable ghrelin receptor agonist (growth hormone secretagogue receptor-1a, GHSR-1a agonist) originally developed by Pfizer for potential human indications. Human development was discontinued, and the compound was subsequently advanced as a veterinary pharmaceutical. Capromorelin is FDA-approved for use in dogs under the brand name Entyce and for cats under the brand name Elura. It is not approved by the FDA, EMA, or any other regulatory authority for use in humans, and no approved human formulation exists.

What Is Capromorelin?

Ghrelin is the endogenous ligand for the growth hormone secretagogue receptor (GHSR-1a). It is produced primarily in the stomach and signals hunger, stimulates growth hormone (GH) release from the pituitary, and influences energy balance. Ghrelin is a 28-amino-acid peptide requiring acylation for full receptor activity. Capromorelin is a small-molecule non-peptide mimetic of ghrelin's receptor-binding activity — it activates GHSR-1a without being a peptide itself. As a GHSR-1a agonist, capromorelin stimulates appetite and promotes growth hormone secretion. Its oral bioavailability — in contrast to peptide GH secretagogues such as ipamorelin or GHRP-6, which require injection — was the primary rationale for its development.

Veterinary Approval: Entyce and Elura

Entyce (capromorelin oral solution, 30 mg/mL) was approved by the FDA Center for Veterinary Medicine (CVM) on May 16, 2016, for appetite stimulation in dogs. The approval was supported by a multi-site, prospective, randomized, masked, placebo-controlled field study involving 244 client-owned dogs with reduced appetite. Treated dogs achieved appetite improvement in 68.6% of cases versus 44.6% in the placebo group. Elura (capromorelin oral solution, 20 mg/mL) received FDA CVM approval in October 2020 for the management of weight loss in cats with chronic kidney disease (CKD) — the first drug specifically approved for this indication in cats. Field studies in approximately 120 cats demonstrated a 3.3% body weight increase after 2 weeks and 5.2% after 8 weeks. Both products are currently marketed by Elanco Animal Health, which acquired Aratana Therapeutics (the company that advanced capromorelin from Pfizer's abandoned program) in 2019.

Human Development: Why It Was Abandoned

Pfizer conducted human trials of capromorelin for conditions including cachexia, frailty, and growth hormone deficiency. Despite demonstrating GH stimulation and some appetite-related signals, the human program was discontinued before regulatory approval. Reasons cited in the published literature and industry commentary included insufficient efficacy signals for the intended indications, tolerability concerns at effective doses, and strategic pipeline prioritization. A 2018 review in Veterinary Medicine and Science (Rhodes et al., PMC5813110) summarizes the compound's trajectory from human candidate to veterinary approval. No pathway for human use is currently active. Capromorelin is not available as a human pharmaceutical in any jurisdiction.

Approved Veterinary Dose Ranges

Not medical advice. These are ranges reported in research literature, not personalized recommendations. Consult your physician.

For reference: Entyce is administered to dogs at 3 mg/kg orally once daily. Elura is administered to cats at 2 mg/kg orally once daily. These are veterinary approved doses with no valid human equivalence. These figures are provided solely for scientific context and do not constitute recommendations for use in humans.

References

See citations below. Key sources: FDA CVM Entyce approval; FDA CVM Elura approval; Rhodes et al. Vet Med Sci 2018 (PMC5813110); Springer capromorelin veterinary review 2023.