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Research information only. Not medical advice. 18+ only. Not FDA-approved for human therapeutic use.

Ipamorelin

Also known as: NNC 26-0161, IPA, Ipamorelin acetate, Aib-His-D-2-Nal-D-Phe-Lys-NH2

Growth Hormone Secretagogue (GHS); Ghrelin Receptor Agonist; Synthetic Pentapeptide

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What it is

Ipamorelin is a synthetic pentapeptide (Aib-His-D-2-Nal-D-Phe-Lys-NH2) and selective growth hormone secretagogue (GHS) that acts as an agonist at the ghrelin receptor (GHS-R1a), stimulating growth hormone (GH) release from the anterior pituitary. Its GH-releasing potency and efficacy in vitro are similar to GHRP-6 (EC50 = 1.3 nmol/L), and it stimulates GH release via a GHRP-like receptor mechanism. Unlike GHRP-2 and GHRP-6, ipamorelin does not significantly elevate ACTH or cortisol at doses more than 200-fold above its GH-releasing ED50 in swine, making it the first described GHS with selectivity for GH release analogous to GHRH. Pharmacokinetic-pharmacodynamic modeling in healthy male volunteers demonstrated dose-proportional kinetics with a short terminal half-life of approximately 2 hours, clearance of 0.078 L/h/kg, and volume of distribution at steady state of 0.22 L/kg; it induces a single episode of GH release peaking at ~0.67 hours. Ipamorelin is described as a growth hormone secretagogue that activates IGF-1 signaling and satellite cell repair pathways. It also exerts GI promotility effects via ghrelin receptor-mediated cholinergic mechanisms, stimulates insulin secretion via calcium channel and adrenergic receptor pathways, and may act peripherally to attenuate visceral and somatic nociception.

Class: Growth Hormone Secretagogue (GHS); Ghrelin Receptor Agonist; Synthetic Pentapeptide

What it's studied for

  • Growth hormone stimulation / GH-IGF-1 axis modulation Mixed
    • Ipamorelin is the first selective GHS; releases GH in rats and swine with potency and efficacy comparable to GHRP-6 but without significant ACTH or cortisol elevation even at >200-fold above the GH ED50. PMID 9849822 Raun K et al. European Journal of Endocrinology (1998)
    • PK/PD study in healthy male volunteers: dose-proportional pharmacokinetics, terminal half-life ~2 h, single episode of GH release peaking at 0.67 h. SC50 for half-maximal GH stimulation = 214 nmol/L. PMID 10496658 Gobburu JV et al. Pharmaceutical Research (1999)
    • Ipamorelin (18–450 µg/day s.c., 3×/day, 15 days) dose-dependently increased longitudinal bone growth rate and body weight in adult female rats. Total IGF-I levels and serum bone markers were unaffected. PMID 10373343 Johansen PB et al. Growth Hormone & IGF Research (1999)
  • Postoperative ileus / gastrointestinal motility Human RCT
    • Phase II multicenter double-blind RCT (n=114): ipamorelin 0.03 mg/kg IV twice daily for up to 7 days after bowel resection was well tolerated. Median time to first tolerated meal: 25.3 h (ipamorelin) vs 32.6 h (placebo); difference not statistically significant (p=0.15). PMID 25331030 Beck DE et al. International Journal of Colorectal Disease (2014)
    • In a rodent model of POI, single IV dose of ipamorelin (1 mg/kg) decreased time to first bowel movement; repetitive dosing (0.1 or 1 mg/kg, 4×/day, 2 days) significantly increased fecal output, food intake, and body weight. PMID 19289567 Venkova K et al. Journal of Pharmacology and Experimental Therapeutics (2009)
    • Ipamorelin (0.014 µmol/kg IV) significantly accelerated gastric emptying in a rat model of gastroparesis compared to vehicle (52% vs 78% meal remaining in stomach at 15 min). Acts via ghrelin receptor-mediated cholinergic mechanism. PMID 27186127 Greenwood-Van Meerveld B et al. Journal of Experimental Pharmacology (2012)
  • Counteracting glucocorticoid-induced muscle and bone catabolism Animal studies only
    • In adult female rats, ipamorelin (100 µg/kg s.c. 3×/day, 3 months) combined with methylprednisolone significantly increased maximum tetanic tension and increased periosteal bone formation rate 4-fold compared to glucocorticoid alone. PMID 11735244 Andersen NB et al. Growth Hormone & IGF Research (2001)
    • Ipamorelin (0.5 mg/kg/day, 7 days) in prednisolone-treated rats reduced hepatic urea cycle enzyme expression, reduced capacity of urea-N synthesis by 20%, neutralized nitrogen balance, and normalized organ N-contents, though less efficiently than GH at the doses given. PMID 19231263 Aagaard NK et al. Growth Hormone & IGF Research (2009)
    • Ipamorelin IV (0.4 or 1.6 mg/kg/day, 4×/day, 10 days) in methylprednisolone-treated rats significantly reduced body weight loss and increased IGF-I levels compared to methylprednisolone alone. Methylprednisolone did not disrupt the GH response to ipamorelin. PMID 10629165 Malmlöf K et al. Growth Hormone & IGF Research (1999)
  • Bone mineral content and longitudinal bone growth Animal studies only
    • Ipamorelin (0.5 mg/kg/day s.c. via osmotic minipump, 12 weeks) increased total tibial and vertebral bone mineral content by DXA in adult female rats; increased cortical BMC was due to increased cross-sectional bone area; volumetric BMD was unchanged. PMID 10828840 Svensson J et al. Journal of Endocrinology (2000)
    • Ipamorelin (18–450 µg/day s.c. 3×/day, 15 days) dose-dependently increased longitudinal bone growth rate from 42 to 52 µm/day in adult female rats. PMID 10373343 Johansen PB et al. Growth Hormone & IGF Research (1999)
  • Musculoskeletal recovery / performance enhancement (combined with CJC-1295) Animal studies only
    • CJC-1295 combined with ipamorelin showed significantly improved maximum tetanic tension in murine models with glucocorticoid-induced muscle loss; findings limited to animal studies with no validated human orthopaedic evidence. PMID 41476424 Mayfield CK et al. American Journal of Sports Medicine (2026)
  • Visceral and somatic pain attenuation Animal studies only
    • Ipamorelin administered intravenously significantly attenuated colonic hypersensitivity and somatic allodynia in a rat model of non-inflammatory visceral hypersensitivity; anti-nociceptive effects were blocked by a ghrelin receptor antagonist. Ipamorelin was described as a peripherally restricted ghrelin mimetic. PMID 32257855 Mohammadi EN et al. Journal of Experimental Pharmacology (2020)
  • Cisplatin-induced weight loss and cachexia prevention Animal studies only
    • Ipamorelin (1–3 mg/kg i.p.) in ferrets inhibited cisplatin-induced weight loss during the delayed phase (48–72 h) by approximately 24%. No anti-emetic effect was observed with intraperitoneal ipamorelin. PMID 39043357 Lu Z et al. Physiology & Behavior (2024)
  • Insulin secretion stimulation In vitro only
    • Ipamorelin (10⁻¹²–10⁻⁶ M) significantly increased insulin secretion from pancreatic tissue fragments of normal and streptozotocin-diabetic rats in vitro. Effect was inhibited by diltiazem, yohimbine, propranolol, and (in diabetic rats) atropine, suggesting calcium channel and adrenergic receptor involvement. PMID 15665799 Adeghate E, Ponery AS. Neuro Endocrinology Letters (2004)
  • Body composition and adiposity modulation Animal studies only
    • Twice-daily s.c. ipamorelin induced a small (~15%) body weight increase and increased relative fat pad weights in both GH-deficient and GH-intact mice by 2 weeks, with increased serum leptin and food intake. Effects on adiposity were GH-independent. PMID 11162489 Lall S et al. Biochemical and Biophysical Research Communications (2001)
  • Reproductive axis modulation (fish model) Animal studies only
    • Ipamorelin acetate (5 or 30 µg for 21 days) in tilapia dose-dependently increased food intake, spermatocyte and spermatid numbers, and serum LH and 11-ketotestosterone concentrations. PMID 38996787 Gouda M, Ganesh CB. Animal Reproduction Science (2024)
  • Pituitary somatotroph cell dynamics Animal studies only
    • Chronic treatment with ipamorelin (21 days) in young female rats increased secretory granule volume density in somatotroph cells. In vitro ipamorelin (10⁻⁸ M) increased the percentage of somatotroph cells and intracellular GH content only in the ipamorelin-pretreated group. PMID 12168778 Jiménez-Reina L et al. Histology and Histopathology (2002)

Community-reported dosing

RouteDoseFrequency / DurationPopulation / contextSource tier
Intravenous infusion4.21, 14.02, 42.13, 84.27, and 140.45 nmol/kg over 15 minutes (5 dose levels)Single infusionhumanResearch PMID 10496658
Intravenous infusion0.03 mg/kg twice dailyUp to 7 days (postoperative day 1–7 or hospital discharge)humanResearch PMID 25331030
Subcutaneous injection0, 18, 90, and 450 µg/day (divided into 3 s.c. injections/day)15 daysanimalResearch PMID 10373343
Subcutaneous injection100 µg/kg three times daily3 monthsanimalResearch PMID 11735244
Subcutaneous (osmotic minipump)0.5 mg/kg per day12 weeksanimalResearch PMID 10828840
Not specified (parenteral, context of rat study)0.5 mg/kg/day7 daysanimalResearch PMID 19231263
Intravenous0.4 or 1.6 mg/kg/day (administered 4 times daily intravenously)10 daysanimalResearch PMID 10629165
Intravenous bolus infusion0.01–1 mg/kg (single dose) or 0.1–1 mg/kg (repetitive: 4 doses/day at 3-h intervals for 2 days)Single dose or 2-day repetitive dosinganimalResearch PMID 19289567
Intravenous (in vivo); organ bath (in vitro)0.014–0.14 µmol/kg; also 1 µM (in vitro organ bath)Single doseanimalResearch PMID 27186127
Intravenous (in vivo); oral (HM01 comparator only)Not specified numerically; described as intravenous administrationSingle dose experimentsanimalResearch PMID 32257855
Intraperitoneal1–3 mg/kgUp to 72 h (every 24 h dosing)animalResearch PMID 39043357
Not explicitly specified (administration to fish)5 or 30 µg per fish21 daysanimalResearch PMID 38996787
In vitro (pancreatic tissue fragments)10⁻¹²–10⁻⁶ MIn vitro incubationin_vitroResearch PMID 15665799
In vivo (route not specified); in vitro10⁻⁸ M (in vitro); chronic dosing regimen not specified numerically in abstract21 days (in vivo); 4 hours (in vitro)animalResearch PMID 12168778
SubcutaneousTwice daily s.c. (exact dose not stated in abstract)2–9 weeksanimalResearch PMID 11162489
Intravenous (rats, swine)ED50 = 80 ± 42 nmol/kg (rats); ED50 = 2.3 ± 0.03 nmol/kg, Emax = 65 ± 0.2 ng GH/mL plasma (swine)Single doseanimalResearch PMID 9849822
Intravenous; intranasalPharmacokinetic doses (intranasal bioavailability ~20% in rats); exact doses not specified in abstractSingle doseanimalResearch PMID 9879640
subcutaneous injection200 mcgonce daily, pre-sleepbiohackers and fitness-focused adults seeking GH optimization[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection300 mcgonce daily, pre-sleepbiohackers and fitness-focused adults seeking GH optimization[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection500 mcgonce daily, pre-sleepintermediate-to-advanced biohackers, bodybuilders[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection300 mcgthree times daily (morning, post-workout, pre-sleep)bodybuilders and advanced biohackers chasing multiple GH pulses per day[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection200 mcgthree times daily (morning, post-workout, pre-sleep)fitness-oriented adults, those cautious about side effects[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection300 mcgonce daily, pre-sleepanti-aging biohackers and longevity-focused adults[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection100 mcgonce daily, pre-sleepbeginners, older adults, or those sensitive to GH secretagogues[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection300 mcgonce daily, pre-sleepadults combining ipamorelin with CJC-1295 (no DAC) or Mod GRF 1-29[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection200 mcgonce daily, pre-sleepadults combining ipamorelin with CJC-1295 (no DAC) or Mod GRF 1-29; entry-level stackers[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection300 mcgthree times daily (morning, post-workout, pre-sleep)advanced bodybuilders stacking ipamorelin with CJC-1295 (no DAC)[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection300 mcgonce daily, pre-sleeppost-injury or post-surgery adults seeking soft-tissue repair[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection200 mcgonce daily, pre-sleepwomen using ipamorelin for body composition or anti-aging[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection500 mcgthree times daily (morning, post-workout, pre-sleep)advanced male bodybuilders seeking aggressive GH output[S] Claude Sonnet 4.6 — synthesized from aggregate training data

Tier key: Research = PMID-cited study · [C] = scraped community source · [S] = model-synthesized from aggregate community reports (softer evidence). How we source.

Safety signals

  • In the Phase II RCT (n=114), any treatment-emergent adverse events occurred in 87.5% of the ipamorelin group vs 94.8% of the placebo group; specific adverse events not detailed in abstract beyond nausea and vomiting endpoints. No significant safety differences from placebo were highlighted. PMID 25331030
  • GH-independent increase in body fat (adiposity), increased food intake, and elevated serum leptin observed in mice treated with ipamorelin (s.c., twice daily), including in GH-intact animals. PMID 11162489
  • Ipamorelin stimulates insulin secretion from pancreatic tissue of normal and diabetic rats in vitro, suggesting potential for glycemic effects. PMID 15665799
  • Class-wide adverse effects reported for GHS/ipamorelin in self-administration literature include endocrine and metabolic disturbances (prolactin and cortisol elevations, appetite changes, dysglycaemia), fluid retention syndromes, musculoskeletal symptoms (myalgia/arthralgia), and injection-site reactions. PMID 42395176
  • Potential cardiovascular strain, insulin resistance, dyslipidemia, and psychiatric instability reported as emerging risks associated with peptides in the GHS class including ipamorelin, particularly with supraphysiological or combined protocols common in bodybuilding. PMID 41880199
  • Gray-market ipamorelin products are at risk of mislabeling or contamination; analogs such as Gly-Ipamorelin (an N-terminal glycine-extended analog) have been identified in seized doping materials, with unknown pharmacological and safety profiles. PMID 29864719
  • Uncertain product composition, dose, and stacking practices in unregulated supply chains pose safety risks; biologically plausible but unproven mitogenic concerns are noted for GH axis-modulating peptides. PMID 42395176
  • In streptozotocin-diabetic mice, ipamorelin IV injection produced substantially higher GH levels (150 ± 35 µg/L) compared to non-diabetic mice (62 ± 11 µg/L), suggesting unpredictable GH axis responses in diabetic subjects. PMID 14630569

Contraindications

  • No specific contraindications are explicitly stated in the reviewed abstracts for ipamorelin. Use in patients with diabetes mellitus may produce unpredictable GH hypersecretion responses (demonstrated in streptozotocin-diabetic mice). PMID 14630569
  • Use by competitive athletes is contraindicated under WADA rules, as ipamorelin is listed on the WADA Prohibited List. PMID 26578461

References

  1. [1] PMID 9849822 — Ipamorelin is the first selective GHS; releases GH in rats and swine with potency and efficacy comparable to GHRP-6 but without significant ACTH or cortisol ele
  2. [2] PMID 10496658 — PK/PD study in healthy male volunteers: dose-proportional pharmacokinetics, terminal half-life ~2 h, single episode of GH release peaking at 0.67 h. SC50 for ha
  3. [3] PMID 10373343 — Ipamorelin (18–450 µg/day s.c., 3×/day, 15 days) dose-dependently increased longitudinal bone growth rate and body weight in adult female rats. Total IGF-I leve
  4. [4] PMID 25331030 — Phase II multicenter double-blind RCT (n=114): ipamorelin 0.03 mg/kg IV twice daily for up to 7 days after bowel resection was well tolerated. Median time to fi
  5. [5] PMID 19289567 — In a rodent model of POI, single IV dose of ipamorelin (1 mg/kg) decreased time to first bowel movement; repetitive dosing (0.1 or 1 mg/kg, 4×/day, 2 days) sign
  6. [6] PMID 27186127 — Ipamorelin (0.014 µmol/kg IV) significantly accelerated gastric emptying in a rat model of gastroparesis compared to vehicle (52% vs 78% meal remaining in stoma
  7. [7] PMID 11735244 — In adult female rats, ipamorelin (100 µg/kg s.c. 3×/day, 3 months) combined with methylprednisolone significantly increased maximum tetanic tension and increase
  8. [8] PMID 19231263 — Ipamorelin (0.5 mg/kg/day, 7 days) in prednisolone-treated rats reduced hepatic urea cycle enzyme expression, reduced capacity of urea-N synthesis by 20%, neutr
  9. [9] PMID 10629165 — Ipamorelin IV (0.4 or 1.6 mg/kg/day, 4×/day, 10 days) in methylprednisolone-treated rats significantly reduced body weight loss and increased IGF-I levels compa
  10. [10] PMID 10828840 — Ipamorelin (0.5 mg/kg/day s.c. via osmotic minipump, 12 weeks) increased total tibial and vertebral bone mineral content by DXA in adult female rats; increased
  11. [11] PMID 41476424 — CJC-1295 combined with ipamorelin showed significantly improved maximum tetanic tension in murine models with glucocorticoid-induced muscle loss; findings limit
  12. [12] PMID 32257855 — Ipamorelin administered intravenously significantly attenuated colonic hypersensitivity and somatic allodynia in a rat model of non-inflammatory visceral hypers
  13. [13] PMID 39043357 — Ipamorelin (1–3 mg/kg i.p.) in ferrets inhibited cisplatin-induced weight loss during the delayed phase (48–72 h) by approximately 24%. No anti-emetic effect wa
  14. [14] PMID 15665799 — Ipamorelin (10⁻¹²–10⁻⁶ M) significantly increased insulin secretion from pancreatic tissue fragments of normal and streptozotocin-diabetic rats in vitro. Effect
  15. [15] PMID 11162489 — Twice-daily s.c. ipamorelin induced a small (~15%) body weight increase and increased relative fat pad weights in both GH-deficient and GH-intact mice by 2 week
  16. [16] PMID 38996787 — Ipamorelin acetate (5 or 30 µg for 21 days) in tilapia dose-dependently increased food intake, spermatocyte and spermatid numbers, and serum LH and 11-ketotesto
  17. [17] PMID 12168778 — Chronic treatment with ipamorelin (21 days) in young female rats increased secretory granule volume density in somatotroph cells. In vitro ipamorelin (10⁻⁸ M) i
  18. [18] PMID 9879640 — Pharmacokinetic doses (intranasal bioavailability ~20% in rats); exact doses not specified in abstract Intravenous; intranasal (animal)
  19. [19] PMID 42395176 — Class-wide adverse effects reported for GHS/ipamorelin in self-administration literature include endocrine and metabolic disturbances (prolactin and cortisol el
  20. [20] PMID 41880199 — Potential cardiovascular strain, insulin resistance, dyslipidemia, and psychiatric instability reported as emerging risks associated with peptides in the GHS cl
  21. [21] PMID 29864719 — Gray-market ipamorelin products are at risk of mislabeling or contamination; analogs such as Gly-Ipamorelin (an N-terminal glycine-extended analog) have been id
  22. [22] PMID 14630569 — In streptozotocin-diabetic mice, ipamorelin IV injection produced substantially higher GH levels (150 ± 35 µg/L) compared to non-diabetic mice (62 ± 11 µg/L), s
  23. [23] PMID 26578461 — Use by competitive athletes is contraindicated under WADA rules, as ipamorelin is listed on the WADA Prohibited List.
  24. [24] PMID 41490200 — in-prose reference
  25. [25] PMID 25869809 — in-prose reference
  26. [26] PMID 41966639 — in-prose reference
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