R2 Medical Clinic

Ipamorelin

What Is Ipamorelin?

Ipamorelin is a synthetic growth hormone secretagogue and ghrelin receptor agonist. It is a short peptide that stimulates the body’s own release of growth hormone (GH) by activating the growth hormone secretagogue receptor type 1a (GHS-R1a), also known as the ghrelin receptor.

Ipamorelin — a pentapeptide ghrelin-receptor agonist — binds the GHS-R1a receptor to trigger a pulse of growth-hormone release.

Ipamorelin is commonly discussed in the peptide and hormone-optimization space because it may increase endogenous GH release without directly administering growth hormone. However, unlike tesamorelin, ipamorelin is not FDA-approved for any medical indication. It is considered an investigational or unapproved peptide in the United States.

The FDA has also identified safety concerns regarding compounded ipamorelin products, including concerns related to peptide impurities, aggregation, and potential immunogenicity.

Mechanism of Action

Ipamorelin acts primarily by binding to and activating the GHS-R1a receptor, the same receptor activated by ghrelin. This receptor is expressed in the pituitary gland and hypothalamus and plays a role in regulating growth hormone secretion.

Activation of GHS-R1a may result in:

  • Increased pulsatile growth hormone secretion
  • Increased downstream IGF-1 production
  • Enhanced lipolysis and fat metabolism
  • Support of lean body mass through GH/IGF-1 signaling
  • Potential effects on gastrointestinal motility through ghrelin-receptor pathways

Ipamorelin is described in the literature as a selective growth hormone secretagogue because early studies found that it stimulated GH release with less apparent stimulation of cortisol, prolactin, ACTH, LH, FSH, or TSH compared with some earlier growth hormone-releasing peptides.

Physiological Effects

The GH/IGF-1 axis governs two primary biological functions: Somatic Growth and Metabolism.

Growth (Somatic & Linear)

  • Bone Growth: GH and IGF-1 promote the division and differentiation of cartilage cells (chondrocytes) in the growth plates of bones, driving linear growth. [1, 2]
  • Muscle Growth: IGF-1 stimulates the proliferation and maturation of muscle fibers, increasing overall protein synthesis and lean body mass. [1, 2]

Metabolism

  • Protein Anabolism: GH accelerates amino acid uptake into cells and enhances protein synthesis while preventing protein breakdown.
  • Lipid Mobilization (Lipolysis): GH triggers the breakdown of triglycerides in adipose tissue, releasing free fatty acids for energy.
  • Carbohydrate Regulation: To conserve glucose for the brain, GH promotes a temporary state of insulin resistance, decreasing glucose uptake in peripheral tissues like muscle. [1, 2, 3, 4, 5]

Potential Benefits

Research suggests ipamorelin may have several biologic effects related to growth hormone signaling. These potential benefits are based on limited human studies, animal studies, and mechanistic data.

Potential benefits may include:

  • Increased endogenous growth hormone secretion
  • Increased IGF-1 signaling
  • Support of lean body mass
  • Improved recovery or tissue repair signaling through GH/IGF-1 pathways
  • Possible improvement in body composition
  • Potential improvement in gastrointestinal motility in postoperative ileus research models
  • Less cortisol or prolactin stimulation compared with some older GH secretagogues

It is important to note that ipamorelin has not been proven or FDA-approved for anti-aging, weight loss, bodybuilding, injury recovery, longevity, or hormone optimization.

Risks & Side Effects

Because ipamorelin is not FDA-approved, its full safety profile is not as well established as approved medications.

Potential risks may include:

  • Injection-site reactions
  • Headache
  • Nausea
  • Dizziness
  • Fluid retention
  • Joint pain
  • Numbness or tingling
  • Carpal tunnel–type symptoms
  • Increased appetite
  • Elevated IGF-1
  • Increased blood glucose or impaired glucose tolerance
  • Potential worsening of insulin resistance
  • Theoretical risk of stimulating growth of existing malignancy due to GH/IGF-1 signaling
  • Potential immunogenicity from peptide aggregation or impurities in compounded products

In FDA review materials regarding compounding, the FDA noted that there are no FDA-approved drug products containing ipamorelin free base or ipamorelin acetate. The FDA also stated that compounded drugs containing ipamorelin acetate may pose safety concerns, including potential immunogenicity related to aggregation or peptide-related impurities.

Contraindications

Ipamorelin should generally be avoided or used only with extreme caution in individuals with:

  • Active malignancy
  • History of cancer without specialist clearance
  • Uncontrolled diabetes
  • Severe insulin resistance
  • Pregnancy or breastfeeding
  • Known hypersensitivity to ipamorelin or formulation components
  • Significant pituitary or hypothalamic disease
  • Unexplained elevated IGF-1
  • Severe edema or active carpal tunnel syndrome

Patients with diabetes, prediabetes, or metabolic syndrome may require careful monitoring because GH secretagogues can affect glucose metabolism.

FDA Approval Status

Ipamorelin is not FDA-approved for any indication in the United States.

It is not FDA-approved for:

  • Growth hormone deficiency
  • Weight loss
  • Anti-aging
  • Bodybuilding
  • Athletic performance
  • Recovery or injury healing
  • Longevity
  • Hormone optimization
  • Postoperative ileus

The FDA has reviewed ipamorelin-related bulk drug substances in the context of compounding and concluded that available information raised safety concerns and did not support inclusion on the 503A Bulks List.

Human & Animal Studies

Human Studies

Human research on ipamorelin is limited compared with FDA-approved peptide therapies.

A pharmacokinetic-pharmacodynamic study in healthy male volunteers evaluated intravenous ipamorelin and found that ipamorelin produced a dose-dependent increase in growth hormone release, with GH peaking shortly after administration and then declining.

A phase 2 randomized proof-of-concept study evaluated ipamorelin as a ghrelin-receptor agonist for postoperative ileus. This study explored safety and efficacy in a surgical setting, but ipamorelin did not become an FDA-approved therapy for this indication.

Animal & Preclinical Studies

Animal studies have evaluated ipamorelin as a selective growth hormone secretagogue and ghrelin mimetic.

Published animal and preclinical studies have shown that ipamorelin can:

  • Stimulate growth hormone secretion
  • Increase body weight or growth-related markers in certain models
  • Counteract glucocorticoid-induced decreases in bone formation in adult rats
  • Affect gastric motility and accelerate gastric emptying in rodent models of postoperative ileus
  • Demonstrate selectivity for GH release compared with some other endocrine hormones

These findings support biologic activity but do not prove safety or efficacy for common off-label uses in humans.

Published Studies

Human Studies

  1. Pharmacokinetic-Pharmacodynamic Modeling of Ipamorelin, a Growth Hormone-Releasing Peptide, in Human Volunteers
    https://pubmed.ncbi.nlm.nih.gov/10496658/
  2. Prospective, Randomized, Controlled, Proof-of-Concept Study of Ipamorelin for Postoperative Ileus
    https://pubmed.ncbi.nlm.nih.gov/25331030/

Animal & Preclinical Studies

  1. Ipamorelin, the First Selective Growth Hormone Secretagogue
    https://pubmed.ncbi.nlm.nih.gov/9849822/
  2. Ipamorelin, a New Growth-Hormone-Releasing Peptide, Induces Longitudinal Bone Growth in Rats
    https://pubmed.ncbi.nlm.nih.gov/10373343/
  3. Methylprednisolone Does Not Inhibit the Release of Growth Hormone by Ipamorelin in Rats
    https://pubmed.ncbi.nlm.nih.gov/10629165/
  4. The Growth Hormone Secretagogue Ipamorelin Counteracts Glucocorticoid-Induced Decrease in Bone Formation of Adult Rats
    https://pubmed.ncbi.nlm.nih.gov/11735244/
  5. Influence of Chronic Treatment With the Growth Hormone Secretagogue Ipamorelin in Young Female Rats
    https://pubmed.ncbi.nlm.nih.gov/12168778/
  6. Efficacy of Ipamorelin, a Novel Ghrelin Mimetic, in a Rodent Model of Postoperative Ileus
    https://pubmed.ncbi.nlm.nih.gov/19289567/
  7. Efficacy of Ipamorelin, a Ghrelin Mimetic, on Gastric Dysmotility in a Rodent Model of Postoperative Ileus
    https://pmc.ncbi.nlm.nih.gov/articles/PMC4863553/

Review Articles

  1. The Safety and Efficacy of Growth Hormone Secretagogues
    https://pmc.ncbi.nlm.nih.gov/articles/PMC5632578/
  2. Growth Hormone Secretagogues: History, Mechanism of Action, and Clinical Development
    https://onlinelibrary.wiley.com/doi/10.1002/rco2.9
  3. Safety and Efficacy of Approved and Unapproved Peptide Therapies
    https://pubmed.ncbi.nlm.nih.gov/41966639/

The information provided on this page is intended for educational and informational purposes only. It is not intended to diagnose, treat, cure, or prevent any disease and should not be considered medical advice.

This content was generated with the assistance of artificial intelligence (AI) and reviewed for general accuracy; however, it may contain errors or omissions and should not replace professional medical judgment. Individuals should consult a qualified healthcare provider before beginning or changing any medical treatment.

Ipamorelin is not FDA-approved for any medical indication in the United States. Its use remains investigational, and any clinical use may be considered off-label or non-approved depending on context. Individual results vary, and no specific outcome or benefit can be guaranteed. Patients should consult a qualified healthcare provider before beginning or changing any medical treatment.

R2 Medical Clinic uses medications sourced from compounding pharmacies. Compounded medications are not approved by the U.S. Food and Drug Administration (FDA). Unlike FDA-approved medications, compounded drugs have not undergone FDA review for safety, effectiveness, or efficacy through the FDA drug approval process. While 503B outsourcing facilities are registered with and inspected by the FDA and must comply with Current Good Manufacturing Practice (CGMP) requirements, the compounded medications they produce are not individually approved by the FDA. Similarly, compounded medications prepared by 503A pharmacies are not FDA-approved and are primarily regulated by state boards of pharmacy, with FDA oversight under applicable federal law.

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