Ipamorelin
Growth Hormone Secretagogue
aka NNC 26-0161 · ipamorelin acetate
A selective growth hormone secretagogue (ghrelin receptor agonist) studied for pulsatile GH release without meaningful cortisol or prolactin elevation.
Sequence
Mechanism of action
Ipamorelin is a selective agonist of the ghrelin receptor, which is part of the growth hormone secretagogue receptor family. It stimulates the pituitary gland to release growth hormone (GH) without significantly affecting levels of cortisol or prolactin. This selective action helps to promote muscle growth and fat loss while minimizing potential side effects associated with other GH secretagogues.
What the evidence actually shows
There are a few small human trials that demonstrate Ipamorelin's ability to increase growth hormone levels without significantly affecting cortisol or prolactin. However, larger and more comprehensive studies are needed to fully understand its long-term effects and safety profile.
Regulatory status
In the UK, Ipamorelin is considered a research compound and is not approved for medical use by the MHRA.
Source ↗Pharmacokinetics
Dosing — what backs each figure
Ipamorelin does have real human trials, but they bear no resemblance to the community protocol: three published/registered studies used intravenous, weight-based dosing (0.03-0.06 mg/kg twice or three times daily for up to 7 days in postoperative ileus, and single 15-minute IV infusions for PK/PD), and the efficacy trials missed their endpoints. No subcutaneous ipamorelin regimen has ever been published in humans, and no therapeutic dose is established.
Intravenous infusions of ipamorelin 0.03 mg/kg versus placebo twice daily, on postoperative day 1 to 7 or until hospital discharge. Well tolerated, but there were no significant differences versus placebo on the key or secondary efficacy endpoints (median time to first tolerated meal 25.3 h vs 32.6 h, p = 0.15)
114-117 adults undergoing small and large bowel resection by open or laparoscopic surgery (phase 2, postoperative ileus) · intravenous
Phase 2 dose-finding study with intravenous ipamorelin arms of 0.03 mg/kg BID, 0.06 mg/kg BID, and 0.06 mg/kg TID versus matching placebo infusions
320 patients following small or large bowel resection with primary anastomosis · intravenous
Dose-escalation PK/PD study with five intravenous infusion rates - 4.21, 14.02, 42.13, 84.27 and 140.45 nmol/kg infused over 15 minutes - eight subjects per dose level. Terminal half-life ~2 h; GH release was a single episode peaking at 0.67 h at all dose levels
Healthy adult male volunteers (8 per dose level) · intravenous infusion over 15 minutes
Ipamorelin 0.01-1 mg/kg (or GHRP-6 20 mcg/kg, or saline vehicle) by intravenous bolus infusion, either as a single dose or as a 2-day repetitive regimen of four doses per day at 3-hour intervals, in a postoperative ileus model. A single 1 mg/kg dose shortened time to first bowel movement; repetitive dosing at 0.1 or 1 mg/kg increased fecal output, food intake and body weight gain
rat (fasted male, laparotomy plus intestinal manipulation) · intravenous bolus · PMID 19289567
Animal doses do not convert to human doses by body weight alone. Route matters too — a compound dosed intraperitoneally in mice tells you little about subcutaneous use.
- Dose
- Research literature cites ~200 to 300 mcg per dose, 1 to 3x/day
- Frequency
- Daily
- Cycle
- 8-12 weeks· unsourced
Why this isn't evidence
Every documented human ipamorelin dose is weight-based and intravenous (0.03-0.06 mg/kg BID/TID for at most 7 days, or 4.21-140.45 nmol/kg infused over 15 minutes) - no published human study has ever used a flat 200-300 mcg subcutaneous dose, and nothing in the literature supports an 8-12 week cycle, which is the same template cycle length repeated across unrelated compounds in this dataset.
This figure is shown because it is what circulates and what people search for — not because it is supported. Cycle lengths in particular tend to be convention copied between compounds rather than anything derived from a compound's own pharmacokinetics.
Handling and storage
Safety
- ·Injection site reactions
- ·Mild headache
- ·Transient flushing
- ·Hypoglycemia
- ·"Joint pain"
- ·Active malignancy
- ·Uncontrolled diabetes (GH affects glucose handling)
- ·Not for human therapeutic use — research chemical
- ·Corticosteroids may reduce the effectiveness of Ipamorelin by increasing cortisol levels.
Water retention, headache, flushing; injection-site reactions
Reported combinations
- ·GHRP-6
- ·CJC-1295
- ·Corticosteroids
Combination claims in this dataset are largely unsourced and should be treated as folk knowledge until a citation appears beside them.
References (3)
- Raun K, Hansen BS, Johansen NL, Thogersen H, Madsen K, Ankersen M, Andersen PH (1998) Ipamorelin, the first selective growth hormone secretagogue ↗European Journal of EndocrinologyPMID 9849822DOI
Original characterisation paper: ipamorelin released GH with potency and efficacy similar to GHRP-6 but, unlike GHRP-6 and GHRP-2, did not increase ACTH or cortisol at doses far above the GH-releasing dose.
- Beck DE, Sweeney WB, McCarter MD (2014) Prospective, randomized, controlled, proof-of-concept study of the Ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients ↗International Journal of Colorectal DiseasePMID 25331030DOI
Multicentre double-blind placebo-controlled phase 2 trial (NCT00672074) in 114 adults undergoing bowel resection; intravenous ipamorelin 0.03 mg/kg twice daily on postoperative days 1-7 or until discharge was compared with placebo for time to tolerance of a standardised solid meal.
- Venkova K, Fraser G, Hoveyda HR, Greenwood-Van Meerveld B (2009) Efficacy of ipamorelin, a novel ghrelin mimetic, in a rodent model of postoperative ileus ↗The Journal of Pharmacology and Experimental TherapeuticsPMID 19289567DOI
Preclinical work showing ipamorelin accelerated gastric emptying and colonic transit in a rat model of postoperative ileus, the basis for the later human trial.
Data provenance
Chemistry and citations on this page were checked against primary sources on 2026-08-14. Values that could not be verified were left blank rather than filled with a plausible guess.
Could not verify
sequence.oneLetter, storage.lyophilized, storage.reconstituted, storage.lightSensitive, reconstitution.solvent