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Ipa2.5
Ipamorelin Research
Mostly mechanism / observational
12 peer-reviewed studies
What the evidence says
Mostly mechanism / observational
Most Ipamorelin studies are mechanism or observational rather than RCTs that measure a clinical effect — keep findings provisional.
Most evidence is from mixed-quality randomised trials published 1998–2024.
Based on 12 studies · 2 RCTs
Confidence
Low confidence
By outcome
Growth hormone & body compositionA selective GH-pulse secretagogue (animal + human PK) with no proven human benefit; it failed its Phase 2 ileus endpoint. · Not established (no outcome data)
Mostly mechanism / observational4 studies
GI motility & postoperative ileus
Mostly mechanism / observational3 studies
Slowing down
Only 1 study in the last 5 years
199820112024
1RCT2014
Beck DE, Sweeney WB, McCarter MD, Beart R · Int J Colorectal Dis (2014)
In plain English: Ipamorelin is a pentapeptide (Aib-His-D-2-Nal-D-Phe-Lys-NH2), which displays high GH releasing potency and efficacy in vitro and in vivo.
Raun K, Hansen BS, Johansen NL, Thøgersen H, Madsen K, Ankersen M, Andersen PH. · Eur J Endocrinol (1998)
Foundational pharmacology paper that named and characterized ipamorelin as the first selective GH secretagogue
Released GH from primary rat pituitary cells with potency/efficacy similar to GHRP-6
Antagonist profiling showed it acts via a GHRP-like (ghrelin) receptor, not the GHRH receptor
In plain English: Ipamorelin dose-dependently increased LGR from 42 microm/day in the vehicle group to 44, 50, and 52 microm/day in the treatment groups (P<0.0001).
Johansen PB, Nowak J, Skjaerbaek C, Flyvbjerg A, Andreassen TT, Wilken M, Orskov H. · Growth Horm IGF Res (1999)
Subcutaneous ipamorelin (18-450 µg/day, 3×/day for 15 days) in adult female rats dose-dependently increased longitudinal bone growth rate and body-weight gain
Notably, treatment did NOT change total IGF-I, IGFBPs, or serum bone-turnover markers
Authors explicitly note that any role in treating growth-retarded children 'requires demonstration in future clinical studies'
In plain English: By a rational approach we were able to reduce the size of the lead compound ipamorelin and simultaneously to reduce hydrogen-bonding potential ... while retaining in vivo potency in swine.
Hansen TK, Ankersen M, Hansen BS, Raun K, Nielsen KK, Lau J, Peschke B, Lundt BF, Thøgersen H, Johansen NL, Madsen K, Andersen PH. · J Med Chem (1998)
Medicinal-chemistry program using ipamorelin as the lead compound to design orally active GH secretagogues
Screened in a rat pituitary assay and tested for in-vivo potency in swine and oral bioavailability in dogs
Most analogues showed 10-55% oral bioavailability; most potent compound ED50 ~30 nmol/kg IV in swine
In plain English: Repetitive dosing of ipamorelin (0.1 or 1 mg/kg) significantly increased the cumulative fecal pellet output, food intake, and body weight gain.
Venkova K, Mann W, Nelson R, Greenwood-Van Meerveld B. · J Pharmacol Exp Ther (2009)
Rat postoperative-ileus model: IV ipamorelin accelerated time to first bowel movement after laparotomy/intestinal manipulation
A single dose shortened time to first bowel movement but did not change cumulative output/food intake; repeated dosing did improve those measures
Provided the preclinical rationale that led to the human postoperative-ileus trials
In plain English: Anamorelin and ipamorelin administered i.p. had beneficial effects in alleviating cisplatin-induced weight loss during delayed phase.
Lu Z, Ngan MP, Liu JYH, Yang L, Tu L, Chan SW, Giuliano C, Lovati E, Pietra C, Rudd JA. · Physiol Behav (2024)
Ferret model of cisplatin chemotherapy: intraperitoneal ipamorelin (1-3 mg/kg) vs vehicle, dosed before cisplatin and every 24 h
Ipamorelin did not affect acute or delayed emesis but reduced associated cisplatin-induced weight loss in the delayed phase (48-72 h) by ~24%
Ipamorelin also inhibited electrical-field-stimulation-induced contractions of isolated ferret ileum (consistent with its ghrelin-receptor GI activity)
In plain English: Ipamorelin is a synthetic peptide with GH releasing properties. We wished to study the metabolic effects of Ipamorelin and GH on selected hepatic measures of alpha-amino-nitrogen conversion during steroid-induced catabolism.
Aagaard NK, Grøfte T, Greisen J, Malmlöf K, Johansen PB, Grønbaek H, Ørskov H, Tygstrup N, Vilstrup H. · Growth Horm IGF Res (2009)
Rat model of prednisolone-induced catabolism comparing ipamorelin vs GH on nitrogen balance and hepatic urea synthesis
Probed whether the GH-axis effects of ipamorelin could mitigate steroid-driven nitrogen wasting
Metabolic/anti-catabolic animal pharmacology — not a clinical efficacy study
In plain English: These data suggest that, at least in the young female rat, the GHS Ipamorelin is able to exert a dynamic control effect on the somatotroph population and on GH hormone content.
Jiménez-Reina L, Cañete R, de la Torre MJ, Bernal G. · Histol Histopathol (2002)
21-day in-vivo ipamorelin dosing followed by in-vitro analysis of rat pituitary somatotroph cells
Increased the volume density of secretion granules in somatotrophs (vs saline)
Did not change somatotroph cell percentage or the ratio of staining cell types
In plain English: The acute response to either IPA or growth hormone releasing hormone (GHRH) in terms of plasma GH was not changed [by methylprednisolone].
Malmlöf K, Johansen PB, Haahr PM, Wilken M, Oxlund H. · Growth Horm IGF Res (1999)
Tested ipamorelin's GH-releasing and growth-promoting effects in rats given the glucocorticoid methylprednisolone
Methylprednisolone reduced body-weight gain but did not blunt the acute GH response to ipamorelin or GHRH
Explored ipamorelin as a potential counter to steroid-induced catabolism — animal model
In plain English: Ipamorelin (0.014 µmol/kg intravenous) resulted in a significant acceleration of gastric emptying ... through the stimulation of gastric contractility by activating a ghrelin receptor-mediated mechanism involving cholinergic excitatory neurons.
Greenwood-Van Meerveld B, Tyler K, Mohammadi E, Pietra C. · J Exp Pharmacol (2012)
Rat gastroparesis/postoperative-ileus model: IV ipamorelin accelerated delayed gastric emptying after abdominal surgery
Reversed the surgery-induced inhibition of acetylcholine- and field-stimulation-induced gastric smooth-muscle contraction in isolated tissue
Identified a ghrelin-receptor + cholinergic-excitatory-neuron mechanism for the prokinetic effect