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Ipamorelin

Tier 1 · Human trials
Also known as NNC 26-0161

The strongest evidence present is Tier 1 human RCT/PK data: a human pharmacokinetic study in healthy male subjects (n=8 per dose level), a Phase I dose-ranging study, and a prospective randomized Phase II proof-of-concept trial for postoperative ileus. However, higher-tier sources agree human efficacy data are very thin — limited to small PK/PD studies and one discontinued/failed Phase II trial — with the majority of evidence deriving from rodent and swine models. Body-composition, sleep, bone and anti-aging benefit claims appear only in tier-3 vendor/clinic material and are explicitly noted as never tested in humans.

Half-life
~2 h
Routes
Subcutaneous · Intravenous · Intramuscular · Intranasal (animal studies) · Oral (animal studies)
Goals
gh stimulation · body composition · fat loss · longevity
Cost / mg
$20

How it works

Vendor and educational profiles describe ipamorelin (NNC 26-0161) as a synthetic five-amino-acid peptide that mimics the natural hunger hormone ghrelin by switching on the ghrelin receptor (GHSR-1a) in the pituitary gland and hypothalamus(vendor claim). According to these sources, this prompts the pituitary to release a pulse of growth hormone (GH), which in turn raises IGF-1 and is said to drive protein synthesis, fat breakdown and tissue repair. What multiple profiles emphasize is its selectivity: animal studies reported that ipamorelin releases GH without raising cortisol, prolactin, ACTH or other pituitary hormones, and expert commentary notes it does so while preserving the body's natural pulsatile GH rhythm rather than flooding the system with a constant elevation.

Overview

Overview

Vendor and educational profiles describe ipamorelin (research designation NNC 26-0161) as a synthetic pentapeptide ghrelin receptor (GHSR-1a) agonist and selective growth hormone (GH) secretagogue, with the structure Aib-His-D-2-Nal-D-Phe-Lys-NH215. These sources report a molecular formula of C38H49N9O5, a molecular weight cited variously as 711.85, 711.86 or 711.9 g/mol, CAS number 170851-70-4, and PubChem CID 9831659.

Vendor profiles and a review state that ipamorelin was first described by researchers at Novo Nordisk in the mid-to-late 1990s, with foundational characterization published by Raun et al. in 1998, and describe it as a third-generation growth hormone-releasing peptide(vendor claim).

Reported Mechanism

Animal studies characterized ipamorelin as the first GHRP-receptor agonist with selectivity for GH release similar to GHRH, identified within a series of compounds lacking the central Ala-Trp dipeptide of GHRP-1, and acting via a GHRP-6-like receptor15. In vitro studies using primary rat pituitary cells reported GH release with an EC50 of 1.3 ± 0.4 nmol/L and an Emax of 85 ± 5%15. Preclinical studies reported GH release in anaesthetised rats with an ED50 of 80 ± 42 nmol/kg and in conscious swine with an ED50 of 2.3 ± 0.03 nmol/kg15.

A notable selectivity finding: animal studies reported that ipamorelin released GH with potency comparable to GHRP-6 but did not release ACTH, cortisol, FSH, LH, prolactin or TSH even at doses more than 200-fold higher than the GH-releasing ED50, whereas GHRP-6 and GHRP-2 raised ACTH and cortisol15. Multiple profiles describe ipamorelin as amplifying pulsatile GH secretion that preserves the natural rhythm and negative feedback rather than producing a flat elevation as seen with exogenous GH. huddlemenshealth states that ipamorelin reduces the inhibitory signal from somatostatin and that the resulting GH surge raises IGF-1, driving protein synthesis, lipolysis and tissue repair6.

Human Clinical Evidence

A human RCT/PK study in 8 healthy male subjects per dose level reported dose-proportional kinetics and a single episode of GH release peaking at 0.67 hours, declining exponentially to negligible levels at all doses1. peptidebreakdown reports that in a Phase I study, intravenous ipamorelin (0.01–1 μg/kg) produced dose-dependent GH release in healthy male volunteers, with GH peaking approximately 40 minutes post-injection and returning to baseline within 2–3 hours; at the highest dose cortisol and prolactin remained unchanged from baseline17.

The only completed efficacy program was a prospective, randomized, controlled Phase II proof-of-concept study for management of postoperative ileus in patients undergoing partial bowel resection, at doses of 0.03 mg/kg BID, 0.06 mg/kg BID and 0.06 mg/kg TID by intravenous infusion2,3. ClinicalTrials.gov describes the trial as enrolling 320 patients across 45 locations, ages 18-85 and weight 40-150 kg, with a primary outcome of gastrointestinal function recovery up to 10 days post-operatively; it started April 2011 with study completion May 20142,3. Note that source counts differ: PeptideGarden and superpower.com describe the completed Phase II RCT as n=114 (licensed by Helsinn Therapeutics) and report that it failed to meet its primary endpoint, with human efficacy data outside this trial absent; the sources do not reconcile the 320 vs 114 figures, and the randomized proof-of-concept trial itself3 describes the study as proof-of-concept and does not report it as a failure. peptpedia states human data is limited to two PK/PD studies and a discontinued Phase II trial, with the majority of evidence deriving from rodent models(vendor claim).

Animal Findings

Animal studies report a range of effects: a rodent postoperative ileus model where a single 1 mg/kg dose decreased time to first bowel movement and repetitive dosing increased fecal output, food intake and body weight11; attenuation of colonic hypersensitivity and somatic allodynia in rats via a ghrelin-receptor-mediated mechanism blocked by antagonist H09008; dose-dependent increases in longitudinal bone growth rate in female rats (from 42 to 52 µm/day) without affecting total IGF-I, IGFBPs or bone turnover markers13; and increased somatotroph secretion-granule density after chronic treatment12. Pepteligence reports GH hypersecretion in streptozotocin-diabetic mice alongside reduced hepatic IGF-I mRNA, and increased fat pad weights suggesting possible GH-independent effects on adiposity(vendor claim). A review reported that CJC-1295 combined with ipamorelin improved maximum tetanic tension in murine glucocorticoid-induced muscle loss, while concluding current evidence does not support clinical use for orthopaedic applications4.

Reported Uses and Claims

A narrative review of growth hormone secretagogues in hypogonadal males19 describes ipamorelin as a potent GH and IGF-1 stimulator that the review suggests may improve body composition and hypogonadal symptoms such as fat gain and muscular atrophy, while the same review notes clinical efficacy data for GH secretagogues including ipamorelin largely remain lacking; another notes such secretagogues were developed to treat GH deficiency9. Lower-tier sources go further: Paragon Sports Medicine asserts (framed as clinical studies) that ipamorelin increases lean muscle mass, may reduce adipose tissue, may enhance slow-wave sleep and may increase bone mineral density, and huddlemenshealth adds largely anecdotal claims of improved recovery, body composition, stamina, sleep and anti-aging(vendor claim). These human benefit claims appear only in tier-3 vendor/clinic material and are explicitly contradicted by PeptideGarden's note that body composition, anti-aging and sleep claims have never been tested in humans.

mypeptidematch describes ipamorelin as commonly combined with the GHRH analog CJC-1295, whose pathways are said to converge synergistically(vendor claim).

What the research shows

101 findings extracted from the 19 sources cited below, strongest evidence first within each group. Every one links to the source it came from.

What human studies found

Based on 5 human trial findings, 14 animal findings and 6 expert opinion findings.

  • human trialIpamorelin induces a single episode of GH release with peak at 0.67 hours1

  • human trialGH concentration declines exponentially to negligible levels after ipamorelin administration at all doses1

  • human trialIpamorelin induces GH release at all dose levels tested1

  • human trialPrimary outcome assessed recovery of gastrointestinal function up to 10 days post-operatively2

  • human trialIpamorelin was studied in a prospective, randomized, controlled, proof-of-concept study for management of postoperative ileus in bowel resection patients3

  • animalIpamorelin demonstrated efficacy in a rodent model of postoperative ileus3

  • animalCJC-1295 combined with ipamorelin showed significantly improved maximum tetanic tension in murine models with glucocorticoid-induced muscle loss4

  • animalIpamorelin administered i.p. (1-3 mg/kg) did not affect cisplatin-induced acute or delayed emesis in ferrets7

Show 17 more findings

  • animalIpamorelin administered i.p. (1-3 mg/kg) inhibited cisplatin-induced weight loss on the last day of delayed phase (48-72 h) by approximately 24%7

  • animalIpamorelin significantly attenuated colonic hypersensitivity in rats with non-inflammatory visceral hypersensitivity induced by dilute acetic acid8

  • animalIpamorelin significantly attenuated somatic mechanical allodynia in rats8

  • animalA single dose of ipamorelin (1 mg/kg) decreased the time to the first bowel movement compared with vehicle in a rodent model of postoperative ileus11

  • animalA single dose of ipamorelin (1 mg/kg) had no effect on cumulative fecal output, food intake, or body weight gain measured 48 h after surgery11

  • animalRepetitive dosing of ipamorelin (0.1 or 1 mg/kg) significantly increased cumulative fecal pellet output, food intake, and body weight gain in a rodent model of postoperative ileus11

  • animalIpamorelin dose-dependently increased longitudinal bone growth rate (LGR) from 42 microm/day in the vehicle group to 44, 50, and 52 microm/day in the treatment groups13

  • animalIpamorelin had a pronounced and dose-dependent effect on body weight gain13

  • animalNNC 26-0235 shows comparable in vivo potency to ipamorelin, GHRP-2, and GHRP-6 following iv administration14

  • animalIpamorelin was able to increase basal GH level by more than 10-fold after oral administration14

  • animalSeveral compounds show high in vivo potency and efficacy in anesthetized rats14

  • expert opinionCurrent evidence does not support the clinical use of ipamorelin for orthopaedic applications4

  • expert opinionSeveral peptide drugs have undergone rigorous approval processes that evaluate both safety and efficacy5

  • expert opinionTherapeutic peptides are a promising tool for treating type 2 diabetes and obesity, for skin rejuvenation, and as hormone analogs for specific diseases and conditions5

  • expert opinionIpamorelin represents an investigational peptide requiring rigorous validation through well-designed clinical trials to establish safety and efficacy for healthspan extension18

  • expert opinionIpamorelin can significantly improve body composition19

  • expert opinionCurrent data on clinical efficacy of growth hormone secretagogues including ipamorelin largely remain lacking19

How it works

Based on 4 human trial findings, 1 human study finding, 20 animal findings, 9 in vitro findings, 4 expert opinion findings and 2 theoretical findings.

  • human trialIpamorelin is a growth hormone releasing peptide1

  • human trialIpamorelin is a ghrelin mimetic3

  • human trialGhrelin is an appetite-stimulatory signal from stomach with structural resemblance to motilin3

  • human trialGhrelin enhances appetite and increases food intake in humans3

  • human studyGhrelin influences interdigestive gastrointestinal motility in humans3

  • animalGhrelin stimulates gastric acid secretion and motility in rats3

  • animalIpamorelin inhibited EFS-induced contractions of isolated ferret ileum by 54.4% with IC=11.7 µM7

  • animalIpamorelin is a peripherally restricted ghrelin receptor agonist8

Show 32 more findings

  • animalThe anti-nociceptive effects of ipamorelin were blocked by ghrelin receptor antagonist H0900, indicating ghrelin receptor-mediated mechanism8

  • animalGhrelin receptor-mediated mechanisms are involved in visceral and somatic hypersensitivity in the absence of active colonic inflammation8

  • animalIpamorelin is a selective growth hormone secretagogue and agonist of the ghrelin receptor11

  • animalGhrelin and ghrelin mimetics stimulate appetite and enhance gastric motility11

  • animalIpamorelin is a GH secretagogue (GHS) that can exert a considerable effect on GH secretion12

  • animalChronic treatment with Ipamorelin over 21 days in young female rats increased the volume density of secretion granules in somatotroph cells (P<0.05)12

  • animalIn the Ipamorelin group, basal intracellular GH content in somatotroph cells over 4 hours was lower than in the saline control group12

  • animalIpamorelin exerts a dynamic control effect on the somatotroph population and on GH hormone content in young female rats12

  • animalIpamorelin is a new and potent synthetic pentapeptide which has distinct and specific growth hormone (GH)-releasing properties13

  • animalIpamorelin treatment did not affect total IGF-I levels, IGFBPs, or serum markers of bone formation and resorption13

  • animalThe number of tartrate-resistant acid phosphatase-positive multinuclear cells in the metaphysis of the tibia did not change significantly with treatment13

  • animalPituitary GH content was unchanged by ipamorelin treatment13

  • animalIpamorelin displays high GH releasing potency and efficacy in vitro and in vivo15

  • animalIn pentobarbital anaesthetised rats, ipamorelin released GH with ED50 = 80+/-42 nmol/kg and Emax = 1545+/-250 ng GH/ml15

  • animalIn conscious swine, ipamorelin released GH with ED50 = 2.3+/-0.03 nmol/kg and Emax = 65+/-0.2 ng GH/ml plasma15

  • animalIpamorelin is the first GHRP-receptor agonist with selectivity for GH release similar to that displayed by GHRH15

  • animalIpamorelin peptide could be easily transported across nasal epithelium16

  • in vitroGly-Ipamorelin was identified as an analogue of GHRP, representing Ipamorelin extended by a N-terminal glycine residue10

  • in vitroIn pituitary cell cultures from Ipamorelin-treated rats, in vitro Ipamorelin treatment at 10(-8) M for 4 hours increased the percentage of somatotroph cells12

  • in vitroOnly in the Ipamorelin-treated group did Ipamorelin, GHRP 6, and GHRH treatment prompt increased intracellular GH content12

  • in vitroIpamorelin is a GH secretagogue14

  • in vitroSeveral compounds from ipamorelin-derived series release GH with high in vitro potency and efficacy in rat pituitary cell assay14

  • in vitroIpamorelin is a pentapeptide (Aib-His-D-2-Nal-D-Phe-Lys-NH2)15

  • in vitroIpamorelin was identified within a series of compounds lacking the central dipeptide Ala-Trp of GHRP-115

  • in vitroIn vitro, ipamorelin released GH from primary rat pituitary cells with potency EC50 = 1.3+/-0.4 nmol/l and Emax = 85+/-5%15

  • in vitroIpamorelin stimulates GH release via a GHRP-like receptor, similar to GHRP-615

  • expert opinionIpamorelin is a growth hormone secretagogue (GHS) that acts as an agonist of the growth hormone secretagogue receptor (GHS-R)9

  • expert opinionIpamorelin, as a ghrelin receptor agonist, mimics the actions of ghrelin in stimulating GH secretion9

  • expert opinionGHRPs are short (3-6 amino acids long) peptides with GH releasing properties10

  • expert opinionIpamorelin is a potent GH and IGF-1 stimulator19

  • theoreticalGrowth hormone secretagogues like ipamorelin activate IGF-1 signaling and satellite cell repair6

  • theoreticalIpamorelin is a ghrelin mimetic7

Dosing

Based on 1 human trial finding, 1 animal finding and 1 expert opinion finding.

  • human trialIpamorelin was evaluated at doses of 0.03 mg/kg BID, 0.06 mg/kg BID, and 0.06 mg/kg TID via intravenous infusion2

  • animalIpamorelin was administered intravenously in the experimental model8

  • expert opinionInformation regarding the indications, dosing, frequency, and duration of treatment with ipamorelin remains unknown4

How the body handles it

Based on 4 human trial findings, 7 animal findings and 1 in vitro finding.

  • human trialIpamorelin shows dose-proportionality in pharmacokinetic parameters1

  • human trialIpamorelin has a short terminal half-life of 2 hours1

  • human trialIpamorelin clearance is 0.078 L/h/kg1

  • human trialIpamorelin volume of distribution at steady-state is 0.22 L/kg1

  • animalPlasma GH response was marginally reduced after ipamorelin treatment13

  • animalPlasma GH response was unchanged after GHRH in ipamorelin-treated animals13

  • animalNNC 26-0235 demonstrated 10% oral bioavailability in dogs14

  • animalIpamorelin demonstrates systemic plasma clearance 5-fold lower than that of GHRP-6 following i.v. bolus injection16

Show 4 more findings

  • animalIpamorelin was mainly excreted in the urine16

  • animalIpamorelin showed moderate resistance towards metabolism with 60-80% of administered dose recovered from bile and urine as intact peptide16

  • animalAfter intranasal application, bioavailability of ipamorelin was approximately 20%16

  • in vitroEstablished in-vitro experiments provided preliminary information considering the potential metabolism of Gly-Ipamorelin after administration10

Safety and side effects

Based on 1 human trial finding, 4 animal findings and 4 expert opinion findings.

  • human trialSecondary outcomes investigated ancillary GI functions and safety/tolerability including adverse events, laboratory and clinical parameters2

  • animalThe ultrastructure of somatotroph cells did not change with Ipamorelin treatment12

  • animalIpamorelin did not affect FSH, LH, PRL or TSH plasma levels in swine15

  • animalGHRP-6 and GHRP-2 resulted in increased plasma levels of ACTH and cortisol, but ipamorelin did not release ACTH or cortisol at levels significantly different from GHRH stimulation15

  • animalIpamorelin lacked effect on ACTH and cortisol even at doses more than 200-fold higher than ED50 for GH release15

  • expert opinionFurther studies are needed before most new peptides can be used safely in humans5

  • expert opinionIpamorelin is an unapproved peptide operating largely outside of regulatory oversight17

  • expert opinionUnapproved peptides like ipamorelin demonstrate outcomes in animal models but rigorous human safety data are scarce17

Show 1 more finding

  • expert opinionIpamorelin lacks long-term safety data and systematic validation compared to FDA-approved peptide agents18

What people use it for

Based on 1 human trial finding, 1 animal finding, 7 expert opinion findings and 1 theoretical finding.

  • human trialPost-operative administration of ipamorelin is expected to reduce time to recovery of Gastrointestinal (GI) function in patients who have undergone partial small and/or large bowel resection2

  • animalPostsurgical intravenous infusions of ipamorelin may ameliorate symptoms in patients with postoperative ileus11

  • expert opinionIpamorelin is among the most popular types of injectable peptide therapy being marketed to patients for orthopaedic injuries4

  • expert opinionTherapeutic peptides are short chains of amino acids used to treat metabolic and endocrine conditions such as obesity and type 2 diabetes5

  • expert opinionNovel, unapproved compounds have emerged and are rapidly expanding into preventive medicine and performance enhancement5

  • expert opinionGrowth hormone secretagogues including ipamorelin have been developed to treat growth hormone deficiency, which causes growth retardation, gastrointestinal dysfunction, and altered body composition9

  • expert opinionIpamorelin is a peptide marketed direct to patients in the gray market17

  • expert opinionIpamorelin is identified as a peptide with applications in growth hormone modulation18

Show 2 more findings

  • expert opinionIpamorelin can ameliorate hypogonadal symptoms including fat gain and muscular atrophy19

  • theoreticalIpamorelin is a growth hormone secretagogue6

Other findings

Based on 2 in vitro findings.

  • in vitroThe structure of Gly-Ipamorelin was characterised by means of high resolution (tandem) mass spectrometry10

  • in vitroThe identity of Gly-Ipamorelin was confirmed by custom synthesis10

Points of contention

Where the evidence is unsettled, thin, or says less than the popular claim — worth knowing before you draw conclusions.

Contested

Trial participant count differs between sources.

ClinicalTrials.gov (NCT01280344) lists 320 actually enrolled patients for the phase II postoperative ileus trial, while PeptideGarden and superpower.com describe the completed Phase II RCT as n=114. Sources do not reconcile these figures.

Contested

Trial outcome framed as both proof-of-concept and outright failure.

The tier-1 trial source (Prospective, randomized, controlled, proof-of-concept study of the Ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients) describes a prospective proof-of-concept study without stating failure, while PeptideGarden and superpower.com state the sole Phase II RCT failed to meet its primary endpoint and was not commercialized.

Limited evidence

Human efficacy evidence is very thin.

Higher-tier sources agree human data is limited to a small PK study (n=8/dose), two PK/PD studies, and one discontinued/failed Phase II trial; the majority of evidence is from rodent and swine models. No human GH-indication efficacy trials have been completed.

Single source

Human body-composition, sleep, bone and anti-aging benefits come only from low-tier vendor/clinic sources.

Claims that ipamorelin increases lean muscle mass, reduces adipose tissue, enhances slow-wave sleep, improves skin/anti-aging, and increases bone mineral density in humans appear only in tier-3 vendor/clinic material (Paragon, huddlemenshealth) framed as clinical studies, and are explicitly contradicted by PeptideGarden's note that such claims have never been tested in humans.

Limited evidence

Some PK figures are extrapolated, not measured for ipamorelin.

PeptideInsight's subcutaneous bioavailability estimate of 65-95% is stated as a general estimate for small peptides in this molecular-weight range rather than a measured ipamorelin value; several kinetic figures are described as not established in published human data.

Using it with other compounds

Check a stack
  • MK-677Same mechanism

    Worth caution

    MK-677 (ibutamoren) is an oral non-peptide that hits the same ghrelin receptor (GHS-R1a) as ipamorelin. Running both means competing for the identical receptor and GH-release pathway, so the effect is redundant rather than additive. MK-677 also produces a long, sustained receptor activation plus notable appetite stimulation and water retention — layering ipamorelin on top adds little extra GH while compounding those side effects. Most people should use one GHS-R1a agonist, not two.

    Tier 3Largely anecdotal — commonly discussed

    Timing Pick one ghrelin-receptor agonist rather than stacking; MK-677's long half-life keeps the receptor occupied for many hours.

    Shares GH axis · IGF1 signaling

  • SermorelinSame downstream effect

    May be complementary

    Sermorelin is a GHRH-receptor agonist, a different upstream pathway from ipamorelin's ghrelin receptor, but both feed into the same GH/IGF-1 axis. Pairing a GHRH analog with a ghrelin-receptor agonist is the well-known two-pronged strategy: sermorelin drives GHRH-side signaling while ipamorelin adds the ghrelin-side push and blunts somatostatin, giving a bigger combined GH pulse while keeping the release pulsatile.

    Tier 2Supported by animal / early studies

    Timing Dose together, on an empty stomach, typically at night to match endogenous GH rhythm.

    Shares GH axis · IGF1 signaling · cAMP PKA

  • TirzepatideStack with caution

    Worth caution

    Ipamorelin activates the ghrelin receptor (GHS-R1a), which can mildly stimulate appetite — the opposite of tirzepatide's central appetite reduction. While ipamorelin is relatively selective and its appetite effect is modest, the two pull in opposite directions on hunger signaling and this is worth understanding before combining.

    Tier 4Theoretical — not established
  • TesamorelinSame downstream effect

    May be complementary

    Tesamorelin is a stabilized GHRH analog acting on the GHRH receptor — a distinct mechanism from ipamorelin's ghrelin receptor — but both raise GH/IGF-1 and support fat loss. Combining a GHRH-side driver with ipamorelin's ghrelin-side amplification produces a larger GH pulse, and tesamorelin's specific strength in reducing visceral fat can complement ipamorelin's reported lipolysis for body-composition goals.

    Tier 2Supported by animal / early studies

    Timing Administer together on an empty stomach; nighttime dosing aligns with natural GH pulses.

    Shares GH axis · IGF1 signaling · cAMP PKA · lipolysis

  • BPC-157

    Proposed as compatible, but the two compounds' own mechanism data did not support the pairing.

  • CJC-1295Complementary

    May be complementary

    Ipamorelin works through a different receptor (the ghrelin/GHS-R1a receptor) than CJC-1295's GHRH-R. GHRH analogs increase the size of each GH pulse while ghrelin-mimetics increase pulse frequency and suppress somatostatin — so the two amplify each other's GH release. This GHRH + GHRP pairing is the classic synergistic GH stack.

    Tier 3Largely anecdotal — commonly discussed

    Timing Commonly co-administered in the same injection, typically on an empty stomach at night.

    Shares GH axis · IGF1 signaling

  • AOD-9604Complementary

    May be complementary

    AOD-9604 drives fat mobilization through a GH-independent route (beta-3 adrenergic/HSL activation, not the GH receptor), while ipamorelin promotes lipolysis indirectly via GH release. Because they hit fat metabolism from different directions and both ultimately raise cAMP-driven hormone-sensitive lipase activity, they can be used together for fat-loss goals without receptor competition.

    Tier 4Theoretical — not established

    Timing Both are often used fasted; no strict separation required.

    Shares lipolysis · cAMP PKA

  • HexarelinSame mechanism

    Worth caution

    Both hexarelin and ipamorelin are growth hormone secretagogues that switch on the exact same pituitary receptor (GHS-R1a) to trigger a GH pulse, so stacking them is largely redundant rather than additive — you're pushing the same button twice. The key difference is selectivity: hexarelin also raises ACTH, cortisol and prolactin and blunts (desensitizes) with continued use, whereas ipamorelin gives a cleaner GH pulse without those extra hormones. For most goals you'd choose one, and ipamorelin is the cleaner GHS-R1a option.

    Tier 2Supported by animal / early studies

    Timing If both are on hand, use one per session rather than doubling up on the same receptor.

    Shares GH axis

Safety and side effects

Safety and Tolerability

Selectivity profile

Animal studies reported that ipamorelin released GH with potency comparable to GHRP-6 but did not release ACTH, cortisol, FSH, LH, prolactin or TSH even at doses more than 200-fold higher than the GH-releasing ED5015. peptidebreakdown reports that at the highest Phase I dose tested, cortisol and prolactin remained unchanged from baseline(vendor claim). Multiple profiles contrast ipamorelin with older secretagogues: GHRP-6 is said to raise cortisol and provoke significant hunger and GHRP-2 to elevate cortisol and prolactin, whereas ipamorelin is described as producing no significant prolactin elevation (eliminating gynecomastia concerns) and no ghrelin-mimetic appetite stimulation.

Human safety data

PeptideGarden reports that the Phase II trial (cited as n=114) provides the largest human safety dataset and was well-tolerated at 0.03 mg/kg BID for up to 7 days, and that the overall evidence base comprises roughly 3 human studies, ~120 subjects in safety data, and ~15 animal studies(vendor claim). Secondary outcomes of the trial investigated safety and tolerability including adverse events and laboratory and clinical parameters2. PeptideGarden also notes there is no FAERS data and no post-marketing surveillance for ipamorelin(vendor claim).

Anecdotal sources report generally mild, dose-dependent side effects such as water retention, joint aches and transient injection-site reactions.

Regulatory status

  • superpower.com states that as of September 2023 the FDA classified ipamorelin as a Category 2 bulk drug substance, prohibiting its use in compounded medications for human administration, and that ipamorelin has never received FDA approval for any indication(vendor claim).
  • mypeptidematch states neither ipamorelin nor CJC-1295 is FDA approved as a standalone drug, but describes both as legally available in the US through licensed compounding pharmacies by prescription(vendor claim).
  • Ipamorelin is on the WADA Prohibited List; a glycine-extended metabolite (Gly-Ipamorelin) has been characterized by high-resolution tandem mass spectrometry in an anti-doping context10.

Overall caveat

Multiple reviews describe ipamorelin as a gray-market, unapproved peptide operating largely outside regulatory oversight that demonstrates outcomes in animal models but lacks rigorous long-term human safety data and systematic validation, requiring well-designed clinical trials to establish safety and efficacy5,17,18. Pepteligence states no published human dosing or safety guidance exists beyond the small PK study (n=8 per dose level), and a review notes indications, dosing, frequency and duration of treatment remain unknown4.

Reconstitution and handling

Dosing

No dose has been established for this compound. Ipamorelin has never received FDA approval for any indication (per superpower.com, one source), and Pepteligence states no published human dosing or safety guidance exists beyond a small pharmacokinetic study (n=8 per dose level), with a review noting indications, dosing, frequency and duration remain unknown4. The figures below are what sources report — not guidance.

Doses used in research and reported protocols

  • The human PK study used 15-minute intravenous infusions at rates of 4.21, 14.02, 42.13, 84.27 and 140.45 nmol/kg1.
  • The Phase I study used intravenous doses of 0.01–1 μg/kg.
  • The Phase II postoperative ileus trial used 0.03 mg/kg BID, 0.06 mg/kg BID, and 0.06 mg/kg TID by intravenous infusion2,3.
  • Anecdotal/vendor sources report a commonly used protocol of 200–300 mcg ipamorelin paired with 200–300 mcg CJC-1295 (with DAC), injected subcutaneously 3–5 times per week 30–60 minutes before sleep, or ipamorelin 200-300 µg once before bed run over 3-6 month cycles, often alongside weekly testosterone; these sources explicitly note these parameters have not been established in published human clinical trials.

Reported onset and time course

  • peptideslabuk states IV delivery produces measurable effects within 5-15 minutes, subcutaneous/intramuscular within 15-30 minutes, peak GH at 30-60 minutes, and GH elevation lasting 60-120 minutes(vendor claim).
  • peptpedia states GH release begins within 10 minutes, peaks at 30-40 minutes and returns to baseline by ~3 hours, with plasma ipamorelin peaking at ~25 minutes and no accumulation with repeated dosing(vendor claim).
  • Profiles report a subcutaneous Tmax of ~15-30 minutes and a subcutaneous bioavailability estimated at 65-95% — noted as a general estimate for small peptides in this molecular-weight range rather than a measured ipamorelin value.
  • Anecdotal sources report sleep improvements within 2–4 weeks and body composition changes around weeks 8–12.

Pharmacokinetics

The tier-1 human PK study reported dose-proportional kinetics, a terminal half-life of approximately 2 hours, clearance of 0.078 L/h/kg, and a volume of distribution at steady state of 0.22 L/kg1. Profiles cite plasma elimination half-life of ~2 hours with metabolism primarily by peptidases, renal excretion, and metabolites detectable up to 24 hours; the ~2 hour figure is noted as not established in humans by mypeptidematch, and peptideslabuk cites a shorter 60-90 minute biological half-life in research models. Profiles state metabolism proceeds via ubiquitous peptidases including DPP-IV, aminopeptidases and carboxypeptidases, and that the N-terminal Aib residue and D-amino acids at positions 3 and 4 resist proteolytic degradation, extending half-life. An animal study reported systemic plasma clearance 5-fold lower than GHRP-6 after IV bolus in rats, ~20% bioavailability after intranasal application, and 60-80% of dose recovered as intact peptide16.

Preparation and Storage

Vendor material reports the ipamorelin blend tested to 99.6% purity (Lot YPB.238), supplied as a lyophilized white powder described as stable refrigerated in aqueous solution(vendor claim). Reconstitution of a lyophilized peptide vial is typically performed with bacteriostatic water; the amount added determines the resulting concentration (for example, adding 2 mL to a 5 mg vial yields 2.5 mg/mL). Sources do not specify a standardized reconstitution volume for research use.

Sources

Ordered by evidence quality — the strongest first.

  1. Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers - PubMed(opens in a new tab)
    Tier 1Web · pubmed.ncbi.nlm.nih.gov
  2. Safety and Efficacy of Ipamorelin Compared to Placebo for the Recovery of Gastrointestinal Function(opens in a new tab)
    Tier 1Web · clinicaltrials.gov
  3. Prospective, randomized, controlled, proof-of-concept study of the Ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients(opens in a new tab)
    Tier 1Web · doi.org · 2014
  4. Injectable Peptide Therapy: A Primer for Orthopaedic and Sports Medicine Physicians.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2026
  5. Therapeutic Peptides in Aesthetic, Metabolic and Endocrine Conditions: Effects, Safety, Clinical Applications, and Future Perspectives.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2026
  6. Therapeutic Peptides in Orthopaedics: Applications, Challenges, and Future Directions.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2026
  7. The growth hormone secretagogue receptor 1a agonists, anamorelin and ipamorelin, inhibit cisplatin-induced weight loss in ferrets: Anamorelin also exhibits anti-emetic effects via a central mechanism.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2024
  8. Attenuation of Visceral and Somatic Nociception by Ghrelin Mimetics.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2020
  9. Growth hormone secretagogues: history, mechanism of action, and clinical development(opens in a new tab)
    Tier 2Web · doi.org · 2020
  10. Analysis of new growth promoting black market products.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2018
  11. Efficacy of ipamorelin, a novel ghrelin mimetic, in a rodent model of postoperative ileus.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2009
  12. Influence of chronic treatment with the growth hormone secretagogue Ipamorelin, in young female rats: somatotroph response in vitro.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2002
  13. Ipamorelin, a new growth-hormone-releasing peptide, induces longitudinal bone growth in rats.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 1999
  14. A new series of highly potent growth hormone-releasing peptides derived from ipamorelin.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 1998
  15. Ipamorelin, the first selective growth hormone secretagogue.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 1998
  16. Pharmacokinetic evaluation of ipamorelin and other peptidyl growth hormone secretagogues with emphasis on nasal absorption.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 1998
  17. Safety and Efficacy of Approved and Unapproved Peptide Therapies for Musculoskeletal Injuries and Athletic Performance.(opens in a new tab)
    Tier 3PubMed · pubmed.ncbi.nlm.nih.gov · 2026
  18. Therapeutic peptides in gerontology: mechanisms and applications for healthy aging.(opens in a new tab)
    Tier 3PubMed · pubmed.ncbi.nlm.nih.gov · 2026
  19. Beyond the androgen receptor: the role of growth hormone secretagogues in the modern management of body composition in hypogonadal males.(opens in a new tab)
    Tier 3PubMed · pubmed.ncbi.nlm.nih.gov · 2020

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