Ipamorelin

What it is

Ipamorelin is a synthetic growth hormone secretagogue originally described by Novo Nordisk researchers in the late 1990s^{[8 ]}. It was developed within a chemistry program studying growth hormone-releasing peptides, or GHRPs, and was notable because it appeared more selective for growth hormone release than earlier GHRPs in the tested animal models^{[8 ]}. PubChem lists ipamorelin under the UNII Y9M3S784Z6 and notes that it has been investigated for ileus^{[1 ]}.

Mechanism

Mechanistically, ipamorelin belongs to the ghrelin receptor agonist family^{[8 ,11 ]}. Ghrelin is an endogenous peptide hormone involved in growth hormone secretion, appetite, gastrointestinal motility, and energy-balance signaling^{[11 –12 ]}. Ipamorelin was reported in preclinical work to stimulate growth hormone release through a GHRP-like receptor pathway, now understood in the broader ghrelin receptor / growth hormone secretagogue receptor context^{[8 ,11 ]}.

Ipamorelin is not the same as growth hormone. It does not replace growth hormone directly; instead, it stimulates growth hormone release from the pituitary when the relevant endocrine axis is responsive^{[8 –9 ]}. In a human pharmacokinetic-pharmacodynamic study, intravenous ipamorelin produced a single growth hormone pulse with a peak around 0.67 hours and a terminal half-life of about two hours^{[9 ]}. These findings are endocrine physiology data, not proof of clinical benefit for anti-aging, fat loss, injury recovery, sleep quality, or athletic performance.

The compound became prominent in wellness and bodybuilding discourse because growth hormone secretagogues are marketed online as tools for “optimization,” recovery, body composition, or age-related growth hormone decline. That public framing runs ahead of the evidence. The published human literature is limited and includes a phase 2 postoperative ileus study that did not show statistically significant efficacy on its primary or secondary endpoints^{[10 ]}.

When used in clinical research, ipamorelin has been administered by intravenous infusion^{[9 –10 ]}. Some noncompliant online and clinic marketing discusses subcutaneous injection, often in combination with CJC-1295 or other peptides, but no FDA-approved ipamorelin product label establishes an approved route, dose, indication, contraindication profile, or patient-monitoring plan^{[2 –7 ]}. This page describes published research and regulatory status only.

Regulatory status

Ipamorelin is not FDA-approved for any indication. No approved US prescribing information for ipamorelin was identified in FDA materials reviewed for this draft, and the available clinical development record is consistent with an investigational compound rather than an approved drug product^{[1 ,7 ,10 ]}.

503A bulks-list status

The current US compounding status is restrictive. Under section 503A of the Federal Food, Drug, and Cosmetic Act, a state-licensed pharmacy or physician compounding from a bulk drug substance generally must use a substance that has an applicable USP/NF monograph, is a component of an FDA-approved drug product if no monograph exists, or appears on FDA’s 503A bulks list^{[2 ]}. FDA’s April 22, 2026 503A category PDF does not list ipamorelin acetate or ipamorelin free base in Category 1, Category 2, or Category 3^{[3 ]}. FDA’s October 29, 2024 Pharmacy Compounding Advisory Committee considered ipamorelin-related bulk drug substances for growth hormone deficiency and postoperative ileus and voted 0 yes, 12 no, and 1 abstention on whether ipamorelin free base and ipamorelin acetate should be placed on the 503A bulks list^{[7 ]}.

The FDA committee minutes state that members who voted no agreed there was a lack of information supporting safety and efficacy for ipamorelin in growth hormone deficiency and postoperative ileus^{[7 ]}. The committee also recorded that ipamorelin acetate received the same 0 yes, 12 no, and 1 abstention result^{[7 ]}. Advisory committee votes are not themselves final FDA rules, but they are an important regulatory signal and should be reviewed with the current 503A bulks-list status before publication^{[7 ]}.

503B Category 2 safety-risk

Under section 503B, outsourcing facilities may compound drug products using bulk drug substances only when the substance appears on FDA’s 503B bulks list or the drug compounded from the substance appears on FDA’s drug shortage list at the time of compounding, distribution, and dispensing^{[4 ]}. FDA’s March 21, 2025 503B nominated-substances category PDF lists ipamorelin acetate in 503B Category 2, meaning FDA identified significant safety risks and does not apply the interim enforcement policy available for Category 1 substances^{[5 ]}. FDA’s safety-risk page lists ipamorelin acetate in Category 2 under the 503B interim policy and notes immunogenicity, aggregation, peptide-related impurity, and characterization concerns^{[6 ]}.

FDA’s safety-risk page also states that a published study identified serious adverse events, including death, when ipamorelin was administered intravenously to improve gastric motility, and that FDA lacks sufficient safety information for certain other injectable routes^{[6 ]}. This language should not be interpreted as proof that ipamorelin caused those events; it is FDA’s stated safety-risk rationale for compounding-policy purposes^{[6 ,10 ]}.

Controlled-substance and anti-doping status

Ipamorelin is not listed in the federal controlled-substance schedules in 21 CFR Part 1308 as reviewed for this draft^{[13 ]}. Lack of DEA scheduling does not make an unapproved drug lawful to sell, prescribe, or compound for human therapeutic use. For competitive athletes, ipamorelin is separately prohibited under the World Anti-Doping Agency list as a growth hormone secretagogue^{[14 ]}.

Date of last regulatory verification: May 5, 2026.

Research summary

Ipamorelin’s best-established research finding is that it can stimulate growth hormone release. Raun and colleagues described ipamorelin as a pentapeptide that released growth hormone from rat pituitary cells and stimulated growth hormone release in rats and swine^{[8 ]}. In swine, the study reported that ipamorelin did not significantly increase ACTH or cortisol at doses far above the ED50 for growth hormone release, unlike some earlier GHRPs^{[8 ]}. That preclinical selectivity finding is the origin of many popular claims that ipamorelin is a “cleaner” growth hormone secretagogue. It remains a preclinical pharmacology finding, not a proven clinical advantage in humans^{[8 ]}.

Human pharmacokinetics

Human endocrine physiology was studied by Gobburu and colleagues in a dose-escalation pharmacokinetic-pharmacodynamic trial in healthy male volunteers^{[9 ]}. The trial included five intravenous infusion-rate groups with eight healthy male subjects at each dose level^{[9 ]}. Ipamorelin pharmacokinetics were dose-proportional, with a reported terminal half-life of about two hours, and growth hormone response was modeled as a single release episode peaking at about 0.67 hours^{[9 ]}. This study supports biological activity in humans, but it was not designed to test clinical outcomes such as strength, fat mass, injury recovery, sleep, frailty, or quality of life^{[9 ]}.

Postoperative ileus phase 2 trial

The main patient-facing clinical trial evaluated ipamorelin for postoperative ileus after bowel resection^{[10 ]}. Beck and colleagues conducted a multicenter, double-blind, placebo-controlled phase 2 proof-of-concept trial in adults undergoing small or large bowel resection^{[10 ]}. Participants received intravenous ipamorelin or placebo twice daily from postoperative day 1 through day 7 or discharge^{[10 ]}. The key efficacy endpoint was time from first dose to tolerance of a standardized solid meal^{[10 ]}.

The ileus trial enrolled 117 patients, with 114 included in the safety and modified intent-to-treat populations^{[10 ]}. Median time to first tolerated meal was 25.3 hours with ipamorelin and 32.6 hours with placebo, but the difference was not statistically significant^{[10 ]}. The authors also reported no significant differences in key and secondary efficacy analyses^{[10 ]}. Treatment-emergent adverse events were common in both groups, consistent with a postoperative inpatient population^{[10 ]}.

Where the evidence ends

No large randomized trial was identified establishing ipamorelin as a treatment for growth hormone deficiency, sarcopenia, obesity, osteoporosis, frailty, sleep disorders, athletic recovery, tendon injury, or anti-aging. FDA’s PCAC specifically reviewed growth hormone deficiency and postoperative ileus as nominated 503A uses and concluded, by vote, that available information did not support inclusion on the 503A bulks list^{[7 ]}.

The broader ghrelin receptor agonist literature shows that the ghrelin/GHS-R1a pathway is biologically important and therapeutically interesting^{[11 –12 ]}. Other ghrelin receptor ligands have been investigated for gastroparesis, cachexia, appetite, and motility-related conditions^{[11 –12 ]}. Those studies should not be imported as evidence for ipamorelin unless they actually tested ipamorelin. Ipamorelin’s own human evidence remains narrow and does not support the wide range of wellness claims found in public marketing.

Overall, ipamorelin has plausible endocrine activity and limited human pharmacology data, but it lacks modern approval-quality clinical evidence for commonly marketed uses. The evidence is strongest for “can stimulate growth hormone release under study conditions,” weak or negative for postoperative ileus efficacy, and insufficient for body composition, longevity, recovery, sleep, and anti-aging claims^{[8 –10 ]}.

Public discourse

Gary Brecka, wellness influencer and self-described biohacker, was reported by AP to sell products including ipamorelin and CJC-1295^{[15 ]}. This is marketing-oriented public commentary and should not be treated as clinical evidence or regulatory approval.

Eric Topol, MD, cardiologist and director of Scripps Research Translational Institute, criticized the public use of unapproved wellness peptides that have not gone through adequate clinical testing^{[15 ]}.

Nick Milazzo, lead researcher at Examine.com, emphasized that “peptides” is too broad a category and that growth hormone-affecting peptides can have systemic effects requiring medical supervision^{[16 ]}.

Layne Norton, PhD, nutrition researcher and public science communicator, described enthusiasm around peptides as outpacing human evidence^{[16 ]}.

Public discourse reflects the views of the speakers cited and does not represent medical advice or the editorial position of ProPeptideGuide.

Side effects and safety

Ipamorelin does not have an FDA-approved label, so there is no regulator-reviewed prescribing information establishing contraindications, common adverse reactions, drug interactions, pregnancy warnings, or long-term safety monitoring^{[2 –7 ]}. Safety discussion therefore has to come from clinical studies, FDA compounding-risk materials, class-based endocrine physiology, and risks of unapproved injectable products.

Adverse events in published research

In the postoperative ileus trial, the overall incidence of treatment-emergent adverse events was high in both groups: 87.5% in the ipamorelin group and 94.8% in the placebo group^{[10 ]}. FDA’s safety-risk page states that serious adverse events, including death, were identified in literature involving intravenous ipamorelin for improving gastric motility^{[6 ]}. Because postoperative patients have substantial baseline risk, causality should not be assumed from this summary alone; nevertheless, FDA cited the literature as part of its compounding safety-risk rationale^{[6 ,10 ]}.

Compounding-related risks

FDA identified specific formulation and quality concerns for compounded ipamorelin acetate, including immunogenicity risks related to aggregation or peptide-related impurities and characterization complexity due to unnatural amino acids^{[6 ]}. These concerns are particularly relevant for injectable peptides because sterility, endotoxin control, identity, potency, and impurity profile directly affect patient risk^{[6 ]}.

Mechanism-based concerns

Growth hormone secretagogue activity creates theoretical and class-based concerns. Increasing growth hormone and downstream IGF-1 signaling may affect glucose metabolism, fluid balance, soft-tissue growth, sleep-disordered breathing risk, neoplasm-related clinical questions, and endocrine interpretation in patients with pituitary or metabolic disease^{[8 –12 ]}. The existing ipamorelin literature does not provide long-term safety data adequate to characterize those risks for wellness or anti-aging use^{[7 –10 ]}.

Noncompliant sourcing

A separate safety category is noncompliant sourcing. FDA has issued warning letters to compounding firms for sterile-drug quality problems involving compounded products that included sermorelin/ipamorelin combinations, including a 2022 warning letter noting a voluntary recall due to lack of sterility assurance^{[17 ]}. That warning letter is not a clinical study of ipamorelin, but it illustrates the quality risks that can arise when unapproved injectable peptide products are prepared or distributed outside robust controls^{[17 ]}.

For athletes, anti-doping status is also a safety and eligibility consideration. WADA lists growth hormone secretagogues and mimetics, including ipamorelin, as prohibited at all times^{[14 ]}.

Available through

Ipamorelin is not currently available through FDA-compliant prescription or compounding channels in the United States as of 2026-05-05^{[2 –7 ]}. It is not FDA-approved, is not on the 503A Category 1 list, was not recommended for 503A bulks-list inclusion by FDA’s Pharmacy Compounding Advisory Committee, and remains in FDA’s 503B Category 2 safety-risk category^{[3 ,5 –7 ]}.

ProPeptideGuide does not link to or endorse grey-market vendors, “research chemical” sellers, online peptide shops, clinics advertising noncompliant ipamorelin, or compounded CJC-1295/ipamorelin products marketed for anti-aging, recovery, fat loss, bodybuilding, or wellness use.