Class 04 · Growth hormone secretagogues · Third-generation GHRP · Selective GHS-R1a agonist

Ipamorelinthe first selective growth hormone secretagogue

A small five-amino-acid peptide that tells your pituitary gland to release a clean, natural pulse of growth hormone — without the side hormones (cortisol, prolactin, hunger signals) that older peptides switch on by accident. It was the first peptide in its class to release growth hormone as cleanly as your own body does. Researchers and clinics use it for body composition, recovery, sleep, and bone support, almost always paired with a partner peptide called CJC-1295. No large human trial has yet proven the body-composition or anti-aging claims — those rest on animal data and growth-hormone physiology, not finished efficacy trials.

Ipamorelin (development code NNC 26-0161) is a synthetic pentapeptide growth hormone secretagogue and selective agonist of the ghrelin / GHS-R1a receptor on pituitary somatotrophs. First characterized by Raun et al. in 1998 (Eur J Endocrinol) as the first GHS to release GH with a selectivity profile resembling GHRH — no co-elevation of ACTH or cortisol even at 200× the GH ED₅₀. A formal human PK/PD study in 40 healthy males established a terminal half-life of ~2 h, dose-proportional (linear) pharmacokinetics, and a single episodic GH pulse peaking ~40 min post-dose and returning to baseline by ~6 h. Advanced through Phase II for postoperative ileus (n=117); well tolerated but primary endpoint not met (median time to first tolerated meal 25.3 vs 32.6 h, p=0.15); program later discontinued for business reasons.

Pentapeptide Aib-His-D-2-Nal-D-Phe-Lys-NH₂ (C₃₈H₄₉N₉O₅, MW 711.85 Da, CAS 170851-70-4), engineered at Novo Nordisk from the GHRP-1 scaffold via NNC 26-0194 with the explicit SAR goal of GH selectivity. Binds GHS-R1a with EC₅₀ ≈ 1.3 nmol/L in rat pituitary cells, activating a Gq/11 → PLC → IP₃ / DAG → intracellular Ca²⁺ cascade that drives exocytosis of GH-containing secretory granules. The non-natural N-terminal α-aminoisobutyric acid (Aib) plus D-amino acids at positions 3–4 confer proteolytic resistance and a half-life ~25% longer than GHRP-2 with ~5× lower clearance than GHRP-6, while the three-dimensional conformation prevents engagement of the secondary ACTH / prolactin pathways activated by older GHRPs. Systemic clearance 0.078 L/h/kg; Vss 0.22 L/kg — consistent with confinement to the central vascular compartment.

1.3 nM GHS-R1a EC₅₀ · rat pituitary · Raun 1998

~2 h Terminal half-life · human PK/PD

0 ACTH / cortisol rise at 200× GH ED₅₀

5 AA Pentapeptide · 711.85 Da

Status

Not FDA-approved · compounded Rx (Cat 1 per 2026 announcement)

Open dose calculator →

Routes

SC injection (practice) · IV (trials)

Originator

Novo Nordisk · NNC 26-0161 · 1998

WADA status

Banned · S2 (all times)

Molecule identity

C₃₈H₄₉N₉O₅

Aib-His-D-2-Nal-D-Phe-Lys-NH₂ · Ipamorelin · NNC 26-0161 · third-generation GHRP · synthetic SPPS (acetate salt) · 711.85 Da

ClassPentapeptide GHS · selective GHRP · GHS-R1a agonist

SequenceAib-His-D-2-Nal-D-Phe-Lys-NH₂ · 5 residues

Molecular weight711.85 Da · C₃₈H₄₉N₉O₅ (free base)

Research codeNNC 26-0161 (Novo Nordisk)

Primary targetGHS-R1a (ghrelin receptor) · anterior pituitary

Signal pathwayGq/11 → PLC → IP₃ / Ca²⁺ → GH exocytosis

Receptor affinityEC₅₀ ≈ 1.3 nmol/L (rat pituitary)

Terminal half-life~2 h (human IV PK/PD)

GH peak time~0.67 h (40 min) post-dose

Clearance0.078 L/h/kg · Vss 0.22 L/kg

SelectivityNo ACTH / cortisol / prolactin at 200× ED₅₀

StorageLyophilized −20 °C · reconst. 2–8 °C × ≤28 d

PK linearityDose-proportional 0.003–0.1 mg/kg IV

Metabolic stability60–80% recovered intact (bile / urine)

vs GHRP-2 / GHRP-6~25% longer t½ · ~5× lower clearance

OriginGHRP-1 analog → NNC 26-0194 → NNC 26-0161

01 · At a glance

Key facts & headline data.

The numbers that define why ipamorelin became the reference "clean" growth hormone secretagogue — robust pulsatile GH release with a selectivity profile no other GHRP matches, a well-characterized human pharmacokinetic profile, and a wide gap between strong mechanistic / preclinical data and the absence of body-composition efficacy RCTs in humans.

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First in class

Selective GHS

Raun et al. 1998 (Eur J Endocrinol) characterized ipamorelin as the first growth hormone secretagogue to release GH with GHRH-like selectivity — full GH efficacy comparable to GHRP-6, yet no ACTH or cortisol release even at doses 200× the GH ED₅₀. This selectivity is the molecule's defining research value.

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Terminal half-life

~2 h

Human PK/PD study (40 healthy males, IV 0.003–0.1 mg/kg): terminal half-life ~2 h, clearance 0.078 L/h/kg, Vss 0.22 L/kg, dose-proportional PK, GH pulse peaking ~40 min and returning to baseline by ~6 h. Plasma peptide persists longer than plasma GH, sustaining smaller secondary pulses.

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Receptor potency

EC₅₀ 1.3 nM

In primary rat pituitary cells ipamorelin released GH with EC₅₀ ≈ 1.3 ± 0.4 nmol/L and Eₘₐₓ ≈ 85% of GHRP-6, via GHS-R1a / Gq/11 / PLC / IP₃ / Ca²⁺ signaling. In vivo ED₅₀ ≈ 80 nmol/kg (rat) and ≈ 2.3 nmol/kg (swine) — essentially identical potency to GHRP-6.

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CJC-1295 synergy

3–5×

Co-administration with the GHRH analog CJC-1295 (Mod GRF 1-29) activates a distinct GHRH-receptor / cAMP-PKA pathway (synthesis + vesicle loading) that converges with ipamorelin's GHS-R1a calcium trigger, producing a supraadditive GH pulse roughly 3–5× either compound alone. The most widely used GH-peptide protocol.

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Phase II · ileus · n=117

p = 0.15

Beck et al. 2014 (Int J Colorectal Dis): IV ipamorelin 0.03 mg/kg BID after bowel resection — median time to first tolerated meal 25.3 h vs 32.6 h placebo (not significant); AE incidence 87.5% vs 94.8% placebo. Well tolerated; primary endpoint not met. The largest published human efficacy trial.

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Regulatory (May 2026)

Cat 1 · pending

After being moved to FDA Category 2 in 2023, HHS Secretary RFK Jr. announced 27 Feb 2026 that ipamorelin would be reclassified to Category 1 (compounding-eligible). As of mid-2026 no formal Federal Register rule has been published; it is not FDA-approved for any indication. WADA-banned (S2).

02 · Mechanism of action

How a selective secretagogue works.

Ipamorelin docks onto the same receptor that the hunger hormone ghrelin uses (GHS-R1a) on the growth-hormone-producing cells of your pituitary. It triggers a calcium signal that makes those cells release a burst of growth hormone — a short, natural pulse rather than a flat, artificial level. What makes it special is what it doesn't do: unlike older peptides, it leaves the stress hormone cortisol, the milk hormone prolactin, and most of the hunger signal alone. The result is a clean GH pulse with fewer unwanted effects.

Five mechanistically linked themes. First — high-affinity GHS-R1a agonism (EC₅₀ ≈ 1.3 nM) on anterior-pituitary somatotrophs, coupling to Gq/11 → PLC → IP₃ → intracellular Ca²⁺ → fusion of GH secretory granules. Second — receptor selectivity: the conformation engages the GH-release arm of GHS-R1a but not the secondary pathways that drive ACTH, cortisol, and prolactin in less selective GHRPs. Third — preservation of the physiological pulsatile secretory pattern, leaving the somatostatin negative-feedback brake intact. Fourth — pharmacological synergy with the GHRH axis: distinct second-messenger systems (cAMP/PKA vs PLC/Ca²⁺) converge for a supraadditive pulse with CJC-1295. Fifth — downstream GH → hepatic IGF-1, lipolysis, and anabolic protein synthesis.

Ipamorelin is a GHS-R1a-selective ghrelin-mimetic. Receptor engagement (EC₅₀ ≈ 1.3 ± 0.4 nmol/L, rat pituitary) activates the Gq/11-coupled cascade — PLC hydrolyzes PIP₂ to IP₃ + DAG, IP₃ mobilizes ER Ca²⁺, and the calcium surge drives exocytosis of GH-containing granules into the portal circulation. Pharmacological profiling with GHRP antagonists confirmed GH release proceeds via the same GHRP-like (GHS-R1a) receptor as GHRP-6, yet ipamorelin does not cross-activate the ACTH/CRH pathways engaged by older GHRPs — the basis for its selectivity. In humans the SC₅₀ for half-maximal GH stimulation was ~214 nmol/L with maximal GH production ~694 mIU/L/h; inter-individual variability was greater for PD than PK parameters, reflecting variation in somatotroph reserve. No appreciable orexigenic, gonadotropic (FSH/LH), or thyrotropic (TSH) effect is observed at GH-active doses.

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GHS-R1a agonism · the calcium trigger

Ipamorelin binds the growth hormone secretagogue receptor 1a — the endogenous ghrelin receptor — expressed on somatotroph cells of the anterior pituitary. Binding (EC₅₀ ≈ 1.3 nmol/L) activates a Gq/11-coupled cascade: PLC → IP₃ → endoplasmic-reticulum Ca²⁺ release → exocytosis of GH secretory vesicles. GH efficacy (Eₘₐₓ ≈ 85% of GHRP-6) is essentially equivalent to GHRP-6 across rat pituitary, anesthetized-rat, and conscious-swine assays.

Clinical significance: This is the "trigger" half of GH-peptide pharmacology — ipamorelin fires the calcium-dependent release of GH already synthesized and loaded in the somatotroph. It is why ipamorelin produces a discrete GH pulse within ~30–40 minutes of injection and why timing around fasting (insulin blunts the GH response) matters in practice protocols.

Molecular detail: GHS-R1a is a Gq/11-coupled GPCR; downstream PLCβ generates IP₃ and DAG, IP₃ binds ER IP₃ receptors to release Ca²⁺, and the cytosolic Ca²⁺ surge drives SNARE-mediated granule fusion. The human PK/PD model used an indirect-response framework with zero-order GH release over a finite duration to capture episodic secretion; GH peaked ~0.67 h post-infusion and declined to near-baseline by ~6 h at all dose levels. Plasma ipamorelin outlasts plasma GH, driving smaller secondary pulses as stores replenish.

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Selectivity · no cortisol, ACTH, or prolactin

The defining feature. Unlike GHRP-2, GHRP-6, and hexarelin, ipamorelin does not stimulate ACTH or cortisol secretion even at supramaximal doses (200× the GH ED₅₀), does not elevate prolactin, and does not modulate FSH, LH, or TSH. Pharmacological profiling confirmed GH release via the GHS-R1a receptor without engagement of the secondary ACTH/CRH and dopaminergic pathways activated by older GHRPs.

Clinical significance: Selectivity translates to a predictable safety advantage — avoiding the catabolism, immunosuppression, and HPA dysregulation of chronic cortisol elevation, and the galactorrhea / testosterone-suppression / gynecomastia risks of hyperprolactinemia. It is the principal reason ipamorelin is preferred over GHRP-6 and GHRP-2 in modern practice-pattern protocols despite similar GH efficacy.

Molecular detail: The selectivity appears conformational: the Aib-anchored N-terminus and the D-2-Nal / D-Phe residues constrain a geometry that activates the GH-release signaling arm while failing to engage the receptor states (or accessory receptor populations) that couple to ACTH and prolactin release in less selective ligands. Raun 1998 established this as the first demonstration of GHRH-grade hormonal specificity in a synthetic GHRP — the result that named ipamorelin "the first selective growth hormone secretagogue."

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Pulsatile release · physiology preserved

Ipamorelin generates a discrete, episodic GH pulse rather than the continuous, supraphysiological elevation produced by exogenous recombinant HGH. Because release occurs through the pituitary's own secretory machinery, the somatostatin negative-feedback brake remains intact — the pituitary cannot be driven past its physiological ceiling, and chronic GHRH-axis suppression seen with exogenous HGH does not occur.

Clinical significance: Preserving pulsatility is thought to maximize downstream IGF-1 generation and anabolic / lipolytic signaling while minimizing the insulin resistance and receptor desensitization associated with flat, continuous GH exposure. It is the mechanistic argument practice-pattern clinicians use to favor secretagogues over direct HGH for body-composition and recovery goals.

Molecular detail: A documented ceiling effect — beyond ~0.1 mg/kg in the human PK study, further dose escalation yields diminishing GH returns, consistent with finite somatotroph releasable-pool size and intact somatostatinergic feedback. IGF-1 elevation with secretagogues is typically more modest (≈20–40%) than with therapeutic HGH (40–100%+), and the relationship between ipamorelin dose, pulse amplitude, and downstream IGF-1 has not been formally characterized across human populations.

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GHRH synergy · the dual-pathway pulse

Ipamorelin's GHS-R1a pathway is pharmacologically distinct from the GHRH-receptor (GHRHR) pathway. When co-administered with a GHRH analog (CJC-1295 / Mod GRF 1-29), GHRHR activates cAMP/PKA signaling that synthesizes and loads GH into vesicles (the "volume knob"), while ipamorelin fires the GHS-R1a calcium cascade that triggers exocytosis (the "trigger"). Convergence on distinct second messengers produces a supraadditive GH pulse ~3–5× either agent alone.

Clinical significance: This is why the CJC-1295 + ipamorelin combination dominates compounding-pharmacy and biohacking GH-peptide practice. The pairing preserves the physiological pulsatile pattern while amplifying its amplitude, the rationale clinicians cite for combination over monotherapy.

Molecular detail: CJC-1295 (Mod GRF 1-29) is a GHRH(1-29) analog; the long-acting DAC variant binds albumin to extend half-life to days, whereas the "Mod GRF 1-29" (no-DAC) form is short-acting and preferred for preserving discrete pulses. Ipamorelin additionally suppresses somatostatin tone modestly via the ghrelin axis, removing inhibition concurrent with GHRH drive — a third contributory mechanism to the supraadditive response.

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Bone, muscle & GI-motility effects

Beyond GH/IGF-1 anabolism, preclinical work documents direct tissue effects. In adult female rats, ipamorelin dose-dependently increased longitudinal bone growth rate from 42 to 52 µm/day (tetracycline labeling at the proximal tibia). In a rodent gastroparesis / intestinal-manipulation model, ipamorelin significantly accelerated gastric emptying via ghrelin-receptor-coupled cholinergic excitatory pathways.

Clinical significance: The GI-motility mechanism was biologically sound and motivated the postoperative-ileus development program; the bone-formation data underpin interest in glucocorticoid-induced osteoporosis. Neither translated into a completed positive human efficacy trial — the ileus RCTs did not meet endpoints and no human bone-density trial has been completed.

Molecular detail: In an 8-month-old rat methylprednisolone model, ipamorelin (100 µg/kg 3× daily) increased periosteal bone formation rate four-fold versus glucocorticoid-only controls and reversed GC-induced loss of calf-muscle tetanic tension. 12-week continuous SC infusion (0.5 mg/kg/day, osmotic minipump) increased bone mineral content by DXA, comparable to GHRP-6 and recombinant GH at equivalent doses. One diabetic-rat study reported increased pancreatic insulin secretion — a theoretical consideration in insulin-related conditions.

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Slow-wave sleep & the nocturnal GH pulse

The largest physiological GH pulse occurs in the first cycle of slow-wave sleep (SWS); pre-sleep ipamorelin is proposed to amplify it. However, a controlled study using the related GHRP-2 found that GHRP-induced GH elevations did not by themselves significantly promote SWS independent of the GHRH axis — suggesting ipamorelin's sleep benefit, if real, may depend on co-administration with a GHRH analog.

Clinical significance: Bedtime, empty-stomach dosing is the most common practice-pattern timing, partly to align with the nocturnal SWS pulse. Community wearable data (e.g. Oura) report subjective deep-sleep increases on CJC-1295/ipamorelin, but this is anecdotal and uncontrolled; polysomnographic confirmation is lacking.

Molecular detail: GH secretion and SWS are bidirectionally coupled through hypothalamic GHRH neurons that both promote SWS and drive somatotroph GH release. A pure GHS-R1a trigger that bypasses GHRH may therefore raise GH without independently deepening SWS, which is the leading interpretation of the GHRP-2 sleep data and the basis for pairing ipamorelin with a GHRH analog when sleep architecture is the target.

03 · Dosing protocols

Dosing ipamorelin.

This is the core of the atlas. Ipamorelin has one FDA-approved indication: none — all human dosing below the clinical-trial IV protocol is practice-pattern, derived from clinical pharmacology, the human PK/PD study, and compounding-pharmacy conventions rather than from dose-finding efficacy trials. The dominant community protocol is 200–300 mcg per subcutaneous injection, once to three times daily, on an empty stomach, very commonly stacked with the GHRH analog CJC-1295. Choose a protocol lane below; each carries an explicit evidence grade. None is FDA-validated; injectable use requires a verified product source and physician oversight.

Starting dose

200 mcg SC once daily at bedtime, on an empty stomach (2+ hours after the last meal). This is the convergent practice-pattern starting dose across compounding-pharmacy protocols, scaled from clinical-trial IV doses to the SC route. A conservative entry of 100 mcg is reasonable for peptide-naïve or sensitive individuals.

Escalation cadence

Hold at the starting dose ≥ 1–2 weeks to confirm tolerability (injection-site response, water retention, sleep effect) before stepping up. There is no efficacy penalty for slower titration.

Dose ladder

100 mcg QD → 200 mcg QD → 300 mcg QD. Most protocols plateau at 200–300 mcg per injection. A documented ceiling effect means doses well above this yield diminishing GH returns rather than proportionally more GH — escalating past 300 mcg per pulse is rarely justified.

Timing

Empty stomach, bedtime preferred. Insulin and dietary fat blunt the GH response, so dosing is separated from meals by ≥2 hours. Bedtime dosing aligns the pulse with the nocturnal slow-wave-sleep GH surge. Note that GHS-only GH elevation may not independently deepen slow-wave sleep without a GHRH analog.

Cycling

8–12 weeks on, 4–8 weeks off, with a within-week 5 days on / 2 days off pattern to preserve receptor sensitivity. No human data demonstrates tachyphylaxis at these doses; cycling is an empirical conservative convention, not an evidence-based requirement.

Reconstitution & injection

Typical 5 mg vial: reconstitute with 2 mL bacteriostatic water → 2,500 mcg/mL. 200 mcg = 0.08 mL = 8 units on a U-100 insulin syringe; 300 mcg = 12 units. Inject SC into abdomen (lateral to navel), thigh, or deltoid; rotate sites; 29–31 G insulin syringe. Roll — don't shake — the vial. Refrigerate 2–8 °C; discard within 28 days of first use; avoid freeze-thaw.

Expected response

Practice-pattern endpoints (uncontrolled): improved sleep quality (subjective), modest body-composition shifts over 8–12 weeks, improved recovery and skin/connective-tissue quality. No human RCT has validated ipamorelin for body composition, fat loss, or anti-aging — endpoint expectations should remain modest and counseling honest.

PK rationale

Single-dose GH pulse peaks ~40 min and resolves by ~6 h; the ~2 h half-life means once-daily dosing produces one discrete daily pulse. Multi-daily dosing (see Intensive lane) is used to recreate the 2–3 daily endogenous pulses lost to somatopause. Weight-based clinical exposure (0.03 mg/kg IV) far exceeds typical SC mcg doses; allometric translation is imperfect.

⚠ Source & purity checkpoint The injectable peptide market spans state-licensed compounding pharmacies and unregulated "research chemical" vendors of widely variable purity and sterility. Use only verified product — HPLC ≥98%, sterility and endotoxin testing, identity by mass spectrometry. Product quality, not peptide pharmacology, is the dominant safety risk in this protocol class.

Rationale

Dual-pathway activation: CJC-1295 (Mod GRF 1-29) drives GHRHR → cAMP/PKA (GH synthesis + vesicle loading); ipamorelin drives GHS-R1a → Ca²⁺ (vesicle exocytosis). Convergence yields a supraadditive pulse ~3–5× either alone. This is the most widely used GH-peptide protocol in compounding-pharmacy practice.

Standard dosing

100–300 mcg CJC-1295 (Mod GRF 1-29) + 100–300 mcg ipamorelin, drawn into the same syringe and injected together SC. A very common fixed combination is 100 mcg + 100 mcg ("100/100") up to 300/300.

Frequency

1× daily (bedtime) for general use, or 2× daily (AM fasted + bedtime) for more aggressive body-composition goals. With the short no-DAC "Mod GRF 1-29," each dose is a discrete pulse; some protocols use up to 2–3× daily.

CJC variant choice

Mod GRF 1-29 (no-DAC) is preferred for preserving discrete pulses (half-life ~30 min). The long-acting CJC-1295 DAC (albumin-binding, half-life ~6–8 days) produces a sustained "GH bleed" that some argue blunts the desirable pulsatility — a point of ongoing practice debate.

Reconstitution

Each peptide reconstituted separately; both can be drawn into one U-100 syringe immediately before injection. Example: 5 mg ipamorelin + 5 mg CJC in separate vials, each in 2 mL BAC → 2,500 mcg/mL; 100 mcg of each = 4 units each = 8 units total drawn.

Monitoring

Baseline and periodic IGF-1 is the most useful objective marker of the combined GH effect; fasting glucose / HbA1c given GH's mild insulin-antagonism; symptom review for water retention, carpal-tunnel-type paresthesia, and joint stiffness (dose-dependent GH effects).

Synergy ceiling

The supraadditive effect reflects simultaneous "volume" (GHRH-driven synthesis) and "trigger" (GHS-driven release) plus modest somatostatin suppression. The pulse remains bounded by somatotroph releasable-pool size — combination amplifies amplitude but cannot bypass the physiological ceiling, preserving the feedback-intact advantage over exogenous HGH.

⚠ Combination ≠ approval CJC-1295 + ipamorelin is not an FDA-approved combination product; both components are individually non-approved and (per the 2026 announcement) compounding-eligible pending formal rulemaking. No combination RCT defines efficacy or long-term safety. Both are WADA-banned (S2).

Concept

The young adult pituitary fires several GH pulses per day. Multi-daily protocols (2–3 injections/day) aim to recreate this pattern, exploiting ipamorelin's ~2 h half-life and discrete pulse to add morning and post-workout pulses to the bedtime dose.

Typical schedule

AM fasted (on waking) + post-workout + bedtime, 200–300 mcg each, each separated from food by ≥2 h. BID (AM + PM) is the common middle ground.

Dose ladder

200 mcg BID → 300 mcg BID → 200–300 mcg TID. Per-pulse dose remains capped by the ceiling effect; the intensive strategy adds pulse frequency rather than per-pulse amplitude.

Block structure

Often run as shorter intensive blocks (4–8 weeks) within a longer cycle, then de-escalated to once-daily maintenance. The frequency burden (multiple daily injections) limits adherence.

Timing discipline

Each pulse requires the fasted window. The post-workout pulse is timed to the anabolic window but must still respect the food-separation rule; whey/carbohydrate intake immediately post-injection blunts GH.

Risk note

Higher cumulative GH exposure raises the dose-dependent GH side-effect profile — water retention, joint stiffness, carpal-tunnel-type paresthesia, and theoretical insulin-sensitivity reduction. Monitor fasting glucose and symptoms; step back if these emerge.

Evidence status

Entirely practice-pattern / theoretical. No human trial compares once-daily vs multi-daily ipamorelin on any objective endpoint; the multi-pulse rationale is extrapolated from endogenous GH physiology, not tested.

⚠ Diminishing returns + burden More frequent dosing increases injection burden, cost, and the dose-dependent GH adverse-event profile without proven incremental benefit. Reserve intensive schedules for defined short blocks under supervision, not indefinite use.

Rationale

GH/IGF-1 supports systemic anabolic and connective-tissue repair signaling. Ipamorelin is frequently combined with the cytoprotective peptide BPC-157 and the actin-regulating TB-500 in research injury-recovery "stacks" targeting tendon, ligament, and muscle healing.

GH-peptide component

200–300 mcg ipamorelin QD–BID, usually with 100–300 mcg CJC-1295 (Mod GRF 1-29) for amplified IGF-1 generation during the repair window.

Common co-peptides

BPC-157 ~250–500 mcg/day SC (often near the injury site) and/or TB-500 ~2–2.5 mg twice weekly. These address local cytoprotection and cell migration through mechanisms independent of GH.

Block length

Typically a 4–8 week recovery block aligned to the injury-rehabilitation timeline, then taper. Longer GH-axis use returns to the cycling logic of the Standard lane.

Bone / steroid context

The strongest preclinical recovery rationale is glucocorticoid-associated catabolism: in rats, ipamorelin reversed corticosteroid-induced muscle weakness and increased periosteal bone formation four-fold — a conceptual basis for use during long-term steroid therapy, not yet tested in humans.

Evidence caveat

These stacks are predominantly preclinical or based on clinical inference. No controlled human trial demonstrates that ipamorelin accelerates tendon, ligament, or muscle healing; the recovery use case is mechanistically plausible but unproven.

Mechanistic basis

GH secretagogues raise systemic IGF-1 and anabolic signaling; ipamorelin specifically increased longitudinal bone growth and bone mineral content in rodent models, providing the connective-tissue-repair rationale that underlies the practice-pattern recovery stacks.

⚠ Stack = stacked unknowns Combining three investigational peptides multiplies the unknowns: none of BPC-157, TB-500, or ipamorelin has a completed human efficacy/safety RCT for tissue repair, and combination data are absent. All are WADA-banned. Physician oversight and verified product sourcing are essential.

Trial dose

The pivotal Phase II postoperative-ileus RCT (n=117) used 0.03 mg/kg IV twice daily on postoperative days 1–7 after bowel resection. Primary endpoint: time to tolerance of a standardized solid meal.

Result

Median time to first tolerated meal 25.3 h (ipamorelin) vs 32.6 h (placebo), p = 0.15 — not statistically significant. AE incidence 87.5% vs 94.8% placebo; no serious drug-attributable safety signals. Well tolerated; primary endpoint not met.

PK study doses

The human PK/PD study used IV 0.003–0.1 mg/kg over a 15-minute infusion in 40 healthy males; PK was dose-proportional, GH response dose-dependent, with a documented ceiling at the highest doses.

Phase IIb

Helsinn Therapeutics enrolled ~320 patients in a larger Phase IIb GI-recovery trial (NCT01280344, from May 2011); the program was discontinued without published efficacy data, reportedly for business rather than safety reasons.

Why this lane exists

For reference and translational context only. The IV weight-based clinical dose (≈2.1 mg for a 70-kg adult per dose) is far higher than the SC mcg doses used in practice, illustrating that practice-pattern protocols are not simply the trial protocol scaled down. This is not a recommendation for IV self-administration.

Bone-study dosing

Rodent bone / glucocorticoid studies used 100 µg/kg SC three times daily for up to 3 months — another reference point showing the gap between high-frequency preclinical dosing and human practice patterns.

⚠ Historical reference, not a protocol The IV doses here are from discontinued clinical-development programs. They are documented for scientific completeness, not as a self-administration guide. No ipamorelin protocol is FDA-approved for any indication.

Global dose bands · subcutaneous practice-pattern

Three per-pulse dose tiers & frequency interpolation.

For the subcutaneous route, ipamorelin is dosed per discrete pulse, not by steady-state plasma level. The engine anchors protocols to three per-injection tiers, defaulting to 200 mcg per pulse — the convergent practice-pattern band. A second axis is pulse frequency (1–3×/day). Because of the documented ceiling effect, escalation favors adding pulses over raising per-pulse dose past ~300 mcg. All values are evidence grade C/D (practice-pattern + PK bridge); no human RCT defines an SC dose.

Band	Per-pulse dose	Typical frequency	Rationale	Grade
Low	100 mcg	1×/day (bedtime)	Conservative entry; peptide-naïve or sensitive individuals. Tolerability assessment before stepping up.	C/D
Standard	200 mcg	1–2×/day	The convergent working band across compounding-pharmacy and biohacking protocols. Default for body-composition / recovery / sleep goals.	C/D
High ceiling	300 mcg	1–3×/day	Upper bound of typical practice. Doses above ~300 mcg/pulse add little GH due to the ceiling effect — flag above 300 mcg/pulse as off-protocol.	D

Daily exposure interpolation · SC (practice-pattern)

Goal intensity	Per pulse	Pulses/day	Daily total	Typical context
Minimal / sleep	100–200 mcg	1 (bedtime)	100–200 mcg	Sleep quality, gentle anti-aging, first cycle
Standard / body comp	200 mcg	1–2	200–400 mcg	Recomposition, recovery, general use
Aggressive	200–300 mcg	2	400–600 mcg	Defined body-composition block, often + CJC-1295
Intensive (short block)	200–300 mcg	3	600–900 mcg	Time-limited intensive block under supervision

Exposure bands are interpolated from compounding-pharmacy write-ups and the human PK profile; they are not anchored to any human dose-response efficacy trial. The weight-based clinical IV dose (0.03 mg/kg ≈ 2.1 mg/70 kg) is an order of magnitude above SC practice doses — allometric scaling does not predict equivalent GH effect across routes. No pediatric ipamorelin dosing protocols exist; pediatric use is off-protocol by default and any pediatric GH-axis intervention belongs to pediatric endocrinology.

Titration logic · engine-ready decision rules

Escalation, hold & stop logic.

Generic heuristics mirroring how clinicians titrate GH-axis therapies — clearly marked unvalidated for ipamorelin. Escalation requires both a tolerability floor (no dose-dependent GH adverse events) and a sub-target response before adding a pulse or stepping per-pulse dose. Hard stops are non-editable and reflect oncologic / endocrine caution.

Decision node	Rule template (generic — not ipamorelin-validated)	Grade
Escalate	If `time_on_therapy ≥ 1–2 wk` at current dose AND no dose-dependent GH AEs (water retention, paresthesia, joint stiffness) AND sub-target response → add one pulse/day or step per-pulse dose by 100 mcg, not to exceed 300 mcg/pulse. Prefer adding pulses over raising per-pulse dose past the ceiling.	C/D
De-escalate	Persistent water retention, carpal-tunnel-type paresthesia, joint stiffness, or fasting-glucose rise temporally linked to a dose step → return to prior dose / frequency and reassess. These are dose-dependent GH effects, not idiosyncratic reactions.	D
Hold	IGF-1 trending above the age/sex reference range, fasting glucose / HbA1c rising into pre-diabetic range, or new persistent paresthesia → hold and reassess the GH-axis exposure. Thresholds borrowed from GH-replacement monitoring, not ipamorelin data.	borrowed · D here
Permanent stop (hard)	Active malignancy or history of hormone-sensitive cancer (GH/IGF-1 are mitogenic; use contraindicated in active or prior hormone-sensitive malignancy despite reassuring in-vitro/animal data); pregnancy / lactation; diabetic ketoacidosis or uncontrolled diabetes; severe heart failure; hypersensitivity. Encode as non-editable red hard-stops.	D

Special populations — renal, hepatic, elderly, diabetic, pregnancy: no ipamorelin PK/PD data stratified by organ function exists. The distinctive systemic axis here is GH/IGF-1 and glucose: ipamorelin antagonizes insulin modestly (a GH class effect), and one diabetic-rat study reported increased pancreatic insulin secretion — both reasons to monitor glycemia. Conservative default: avoid in active/prior hormone-sensitive cancer, uncontrolled diabetes, pregnancy, and significant heart failure outside IRB-approved protocols.

Biomarker scaffold · borrowed, not validated

Response & safety monitoring bundles.

No ipamorelin trial defines a biomarker-based efficacy endpoint or MCID. Each bundle below is imported from GH-replacement / GH-axis standard of care and flagged validated_for_ipamorelin = false. The engine drives titration off the direction of change and whether the borrowed threshold is met. IGF-1 is the single most useful objective marker of cumulative GH effect.

Timepoint / bundle	Labs / tests	Interpretation (borrowed)	Validated?
Baseline	IGF-1 (age/sex-adjusted), fasting glucose + HbA1c, fasting insulin, CMP, CBC, lipid panel; TSH/free-T4 if symptomatic; pregnancy test if applicable	Establish GH-axis and glucose baseline before secretagogue exposure. Screen for undiagnosed dysglycemia and contraindications.	No
Week 4–6	IGF-1, fasting glucose ± HbA1c; symptom review (water retention, paresthesia, joint stiffness, sleep)	IGF-1 should rise modestly (≈20–40%) and stay within the age-adjusted reference range; a rise above range or rising fasting glucose → hold/step back.	No
End-of-cycle (8–12 wk)	IGF-1, HbA1c, CMP, lipids; body-composition (DXA / circumference) if that is the endpoint	Confirm IGF-1 / glucose trajectory; document objective body-composition change against subjective report; decision on next cycle.	No
Sleep bundle	Wearable deep-sleep tracking (Oura/WHOOP) ± formal polysomnography if rigorous	Subjective/wearable deep-sleep gains are reported but uncontrolled; GHS-only GH elevation may not deepen SWS without a GHRH analog. Direction of change only.	No
Body-composition bundle	DXA lean / fat mass, waist circumference, standardized photos, strength metrics	Percentage change over the cycle is the surrogate; no validated ipamorelin-specific target exists — interpret against the patient's own baseline.	No

Architecture note: store each biomarker with a source_context tag and a validated_for_ipamorelin boolean (currently false for all efficacy endpoints). IGF-1 and fasting glucose are the two bundles with a clear mechanistic — not yet ipamorelin-trial-validated — rationale, because they track the GH/IGF-1 axis and GH's insulin-antagonism directly.

Standard SC 12-week ladder · practice-pattern

Visual titration: from start to cycle-out.

Wk 1–2 100 mcgInitiation QD bedtime · tolerability test

Wk 3–6 200 mcgStep 2 QD bedtime · standard band

Wk 7–10 200 mcgStep 3 ± AM pulse / + CJC-1295 if sub-target

Wk 11–12 200 mcgPlateau Maintenance · end-of-cycle labs

Wk 13–16 Washout4 wk off Cycle break · reassess IGF-1

Wk 17+ ResumeRepeat If benefit clear · 200 mcg again

L2 · Reconstitution & dose math

Reconstitution & Dose Calculator

For reference only. Not medical dosing advice. Ipamorelin is dosed in micrograms (mcg). Verify peptide purity (≥98% HPLC), sterility, endotoxin limits, and storage. Only use product from a licensed source for any injection protocol.

Vial size (mg)

BAC water (mL)

Target dose (mcg)

Syringe

Concentration

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Draw volume
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Units (U-100)

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Doses per vial

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Cadence basis

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04 · Combination protocols

Stacking ipamorelin.

Ipamorelin is rarely used alone — its dominant clinical and community use is as the "trigger" half of GH-peptide combinations, and as a GH-axis component within broader recovery, body-composition, and longevity stacks. The pairings below reflect mechanistic complementarity, compounding-pharmacy practice patterns, and reasonable extrapolation from GH/IGF-1 physiology. None is an FDA-approved combination product. Investigational combination use requires physician oversight, verified product sourcing, and glucose/IGF-1 monitoring.

Ipamorelin 100–300 mcg CJC-1295 / Mod GRF 1-29 100–300 mcg SC · co-injected · 1–2×/day Empty stomach

The default and most-studied GH-peptide combination. CJC-1295 supplies GHRH-receptor drive (cAMP/PKA → GH synthesis and vesicle loading) while ipamorelin supplies the GHS-R1a calcium trigger for exocytosis; convergence on distinct second messengers yields a supraadditive GH pulse ~3–5× either alone while preserving the physiological pulsatile pattern. The "Mod GRF 1-29" no-DAC variant is preferred for discrete pulses; CJC-1295 DAC gives sustained elevation that some argue blunts pulsatility.

Component	Role	Evidence
Ipamorelin	GHS-R1a trigger · selective GH release	Preclinical + PK (B/C)
CJC-1295 (Mod GRF 1-29)	GHRHR drive · GH synthesis/loading	Mechanistic (C)
Combined pulse	Supraadditive 3–5× amplitude	Mechanistic / practice (C/D)

Ipamorelin 200–300 mcg CJC-1295 100–300 mcg BPC-157 250–500 mcg/day TB-500 2–2.5 mg 2×/wk

A practice-pattern injury-recovery stack. Ipamorelin (± CJC-1295) supplies systemic GH/IGF-1 anabolic and connective-tissue signaling, while BPC-157 provides local cytoprotection and angiogenesis and TB-500 supports cell migration via actin regulation — complementary mechanisms operating at different levels of the repair cascade. Run as a defined 4–8 week block aligned to rehabilitation, then taper. Combination efficacy is unproven in humans.

Component	Mechanism	Status
Ipamorelin + CJC	Systemic GH / IGF-1 anabolism	Investigational (C/D)
BPC-157	Cytoprotection · angiogenesis · NO axis	Investigational (D/C)
TB-500	Actin sequestration · cell migration	Investigational (D/C)

Ipamorelin 200 mcg + CJC-1295 Semaglutide / Tirzepatide (GLP-1 / GIP-GLP-1) Resistance training + protein

An emerging practice-pattern rationale: GLP-1-class weight loss causes substantial lean-mass loss alongside fat loss, and the GH/IGF-1 axis is anabolic for muscle. Ipamorelin + CJC-1295 is proposed to help preserve lean mass during GLP-1-driven weight loss — a plausible but unproven hypothesis flagged in the future-research agenda; no trial has tested the combination. GH's mild insulin-antagonism is a theoretical counterweight to GLP-1's glycemic benefit, so glucose monitoring is essential.

Component	Role	Evidence
Ipamorelin + CJC	Anabolic lean-mass support	Hypothesis (D)
GLP-1 / GIP-GLP-1	Appetite ↓ · weight loss	FDA-approved (A)
Resistance training	Primary lean-mass stimulus	Established (A)

MK-677 (oral, sustained) Tesamorelin (GHRH analog) Sermorelin (GHRH 1-29)

These are generally chosen instead of ipamorelin rather than stacked with it on the same axis. MK-677 (ibutamoren) is an oral GHS with a ~24 h half-life producing sustained rather than pulsatile elevation (more water retention, appetite, and insulin-resistance signal); tesamorelin is the only FDA-approved GHRH analog (HIV-associated lipodystrophy); sermorelin is a shorter GHRH(1-29) analog. A GHS (ipamorelin) plus a GHRH analog (tesamorelin/sermorelin/CJC) is the rational dual-axis pairing — combining two GHS agents adds little.

Agent	Axis	Pairs with ipamorelin?
MK-677	GHS (oral)	Redundant (same axis)
Tesamorelin	GHRH analog	Yes (complementary)
Sermorelin	GHRH analog	Yes (complementary)

Agent	Mechanism	Selectivity / GH pattern	Half-life	Route	Status
Ipamorelin	GHS-R1a agonist (3rd-gen GHRP)	Highest selectivity · clean pulsatile	~2 h	SC (IV trials)	Not approved · Cat 1 pending (B/C)
GHRP-2	GHS-R1a agonist (2nd-gen)	Moderate · mild cortisol/prolactin	~15 min	SC / injectable	Phase II · investigational (C)
GHRP-6	GHS-R1a agonist (1st-gen)	Lowest · strong hunger, cortisol	~20 min	SC / injectable	Phase II · investigational (C)
Hexarelin	GHS-R1a agonist (2nd-gen)	Low · significant cortisol/prolactin · desensitizes	~70 min	SC / injectable	Investigational (C)
MK-677 (ibutamoren)	Non-peptide GHS (oral)	Sustained (not pulsatile) · ↑ appetite	~24 h	Oral	Investigational · extensive data (B/C)
CJC-1295 (Mod GRF 1-29)	GHRH analog (GHRHR)	GH synthesis/loading · pairs with GHS	~30 min (DAC: ~6–8 d)	SC	Investigational (C/D)
Recombinant HGH	Direct GH receptor agonist	Continuous · bypasses feedback	~2–4 h (SC depot)	SC	FDA-approved (A)

05 · Safety profile & contraindications

Clean selectivity; GH-axis & glucose caveats.

Ipamorelin's selectivity gives it a pharmacologically predictable safety advantage over older GHRPs: by not activating ACTH/cortisol or prolactin, it avoids the consequences of chronic cortisol elevation and hyperprolactinemia. In the pivotal Phase II trial it was well tolerated, with a lower total adverse-event burden than placebo. The genuine considerations are the dose-dependent effects of any GH-axis intervention (water retention, paresthesia, joint stiffness, mild insulin antagonism), the theoretical mitogenic risk of GH/IGF-1 in malignancy, and — as with all compounded peptides — product source quality. No long-term human safety data exists; the longest formal human exposure was 7 days. Pregnancy, lactation, pediatric, and active-malignancy populations are off-protocol by default.

Observed AE Profile (Phase II + practice-pattern)

Injection-site reactionsMild erythema or pain at the SC site — ~8–9% in clinical data. Self-resolves within 24–48 h. Rotate sites; check injection technique.

Water retention / bloatingMild, usually transient — ~12% in clinical data. A dose-dependent GH effect; reduce dose or frequency if persistent.

Transient fatigueReported in the first 1–2 weeks (~6%); usually self-limited as the GH axis adjusts.

Mild headache~4% in clinical data; mild and self-limited. Hydration and dose adjustment typically suffice.

Joint stiffness~3–4%; a classic dose-dependent GH effect. Step back the dose if it interferes with function.

Paresthesia (tingling/numbness)Infrequent, mild — a GH-mediated fluid-shift effect (carpal-tunnel-type). Dose-reduce if persistent.

Transient nauseaOccasional and mild; less than with GHRP-6. Usually resolves with dose adjustment.

Increased appetite · minimalFar less than GHRP-6 or ghrelin — the selective ghrelin-mimicry produces only a minimal orexigenic effect at GH-active doses.

Discontinuation · lowPivotal Phase II: overall AE incidence 87.5% ipamorelin vs 94.8% placebo — no excess AE burden attributable to the drug. Practice-pattern discontinuation for side effects is low (~5%).

Specialty Safety Signals & Unknowns

Active or prior hormone-sensitive malignancyGH/IGF-1 are mitogenic; the IGF-1 receptor is implicated in breast, prostate, and endometrial cancer progression. In-vitro and murine data did not show tumor promotion (no growth of breast-cancer cells; no tumor growth in a colon-cancer model), but human cancer-safety data are absent. Contraindicated in active or prior hormone-sensitive cancer.

Diabetes / insulin resistanceGH acutely antagonizes insulin (a class effect). One diabetic-rat study reported increased pancreatic insulin secretion. The pulsatile pattern is thought to minimize the insulin-resistance risk vs continuous HGH, but monitor fasting glucose / HbA1c; avoid in uncontrolled diabetes or DKA.

Pregnancy / lactationNo safety data; unknown fetal/neonatal effects. Avoid.

Severe cardiovascular disease / heart failureFluid shifts and GH effects on cardiac remodeling. Avoid in significant CV disease / decompensated HF pending specialist input.

Long-term human safety · unknownThe longest formal human exposure was 7 days (postoperative-ileus protocol); chronic-use safety is uncharacterized. Reasonable to cycle and reassess rather than use continuously and indefinitely.

Source & purity (injectable)The compounding / research-vendor market varies widely in purity, sterility, endotoxin, and identity. Most documented adverse events with injectable peptides trace to product quality rather than peptide pharmacology. Third-party HPLC ≥98% and sterility/endotoxin testing are essential.

Drug-interaction data · absentInteractions with thyroid medication, glucocorticoids, insulin, and other hormonal therapies have not been systematically studied; GH-axis effects on glucose handling are the most predictable interaction concern.

Competitive athletesWADA Prohibited List S2 (peptide hormones / GH secretagogues) — banned at all times, all routes, under strict liability. USADA-banned. Not a safety issue but an eligibility one with career consequences.

Contraindication reference

Condition / factor	Risk level	Applies to	Rationale
Active malignancy	Avoid	All	GH/IGF-1 promote cell proliferation; theoretical risk of promoting existing tumor growth. No human cancer-safety data.
History of hormone-sensitive cancer (breast/prostate/endometrial)	Avoid	All	IGF-1 receptor implicated in progression of these malignancies. Oncology clearance required before any GH-axis intervention.
Pregnancy	Avoid	All	No safety data; unknown fetal effects of GH-axis stimulation.
Lactation	Avoid	All	Breast-milk excretion and infant exposure unstudied.
Pediatric (< 18 years)	Avoid	All (non-research)	Insufficient safety data; any pediatric GH-axis intervention belongs to pediatric endocrinology.
Diabetic ketoacidosis / uncontrolled diabetes	Avoid	All	GH antagonizes insulin; acute glucose dysregulation risk.
Severe cardiovascular disease / heart failure	Avoid	All	Fluid shifts and GH effects on cardiac remodeling.
Hypersensitivity to ipamorelin / components	Avoid	All	Anaphylaxis risk; discontinue and seek care for angioedema, urticaria, stridor.
Compounded product from unverified source	Avoid	Injectable	Unregulated peptide market includes products of poor purity, sterility, or identity. Use only verified-source product.
Pre-diabetes / insulin resistance	Caution	All	GH's insulin-antagonism may worsen glycemia. Monitor fasting glucose / HbA1c; favor lowest effective dose.
Active acromegaly / pituitary tumor	Avoid	All	Further GH stimulation is contraindicated in GH-excess states.
Concurrent corticosteroid therapy	Monitor	All	GH-axis and glucocorticoid effects on glucose interact; monitor glycemia. (Note preclinical anti-catabolic rationale is unproven in humans.)
Untreated thyroid dysfunction	Monitor	All	Thyroid status modulates the GH/IGF-1 axis; optimize thyroid function and monitor.
Competitive (drug-tested) athlete	Avoid	All	WADA S2 banned at all times; strict-liability anti-doping violation.

Suggested monitoring for ipamorelin protocols

Baseline

IGF-1 (age/sex-adjusted), fasting glucose + HbA1c, fasting insulin, CMP, CBC, lipid panel; TSH/free-T4 if symptomatic; pregnancy test if reproductive potential. Body-composition baseline (DXA / circumference / photos) and/or sleep tracking if those are the endpoints.

Week 4–6

IGF-1, fasting glucose ± HbA1c; symptom review (water retention, paresthesia, joint stiffness, sleep). Decision: continue, hold for tolerability, or step back. Confirm IGF-1 within age-adjusted range.

End of cycle (8–12 wk)

Repeat IGF-1, HbA1c, CMP, lipids. Objective endpoint review (DXA / strength / sleep metrics). Patient-reported satisfaction and adherence. Decision: new cycle, modify, or washout.

Washout (4–8 wk off)

Confirm IGF-1 returns toward baseline; persistent elevation defers the next cycle. Reassess goals and risk/benefit before resuming.

Annual / sustained use

Full repeat baseline panel for repeated cyclers. Age-appropriate cancer screening current and unremarkable before continuing a mitogenic-axis intervention. Reassess indication and continued benefit.

Stop / hold criteria

New malignancy diagnosis, planned/confirmed pregnancy, IGF-1 above age-adjusted range, fasting glucose / HbA1c rising into pre-diabetic range, persistent paresthesia or joint dysfunction, severe injection reaction, or any new contraindicating diagnosis.

06 · Key studies & research program

Strong mechanism, real PK, no body-composition RCT.

Ipamorelin is among the most heavily characterized third-generation GHRPs at the mechanistic and pharmacokinetic level — yet its clinical-development arc ended without a positive efficacy trial, and no randomized controlled trial has ever tested its widely-claimed body-composition or anti-aging effects in humans. Below are the studies that define what is actually known, and where the field's central evidence gap remains.

B Discovery · anchor (preclinical)

Raun et al. 1998 — the first selective GHS (Eur J Endocrinol)

The landmark characterization: ipamorelin releases GH with EC₅₀ ≈ 1.3 nM in rat pituitary cells (Eₘₐₓ ≈ 85% of GHRP-6) and with in-vivo potency essentially identical to GHRP-6 (rat ED₅₀ ≈ 80 nmol/kg; swine ≈ 2.3 nmol/kg) — yet produces no ACTH or cortisol release even at 200× the GH ED₅₀. The result that named ipamorelin "the first selective growth hormone secretagogue." Foundational for the entire selective-GHRP concept.

PubMed

C Phase I · human PK/PD

Svensson et al. 1999 — human PK/PD, 40 healthy males (J Endocrinol)

IV ipamorelin 0.003–0.1 mg/kg over 15 min in 40 healthy males: terminal half-life ~2 h, clearance 0.078 L/h/kg, Vss 0.22 L/kg, dose-proportional (linear) PK. A single episodic GH pulse peaked ~0.67 h post-infusion and returned to near-baseline by ~6 h; SC₅₀ ~214 nmol/L; maximal GH production ~694 mIU/L/h; no ACTH/cortisol elevation; a ceiling effect at the highest doses. PD variability exceeded PK variability. The definitive human pharmacology dataset.

PubMed

P Preclinical · bone growth

Johansen et al. 1999 — longitudinal bone growth in rats (Growth Horm IGF Res)

A 15-day dose-escalation study in adult female rats (18, 90, 450 µg/day, 3× daily SC): ipamorelin dose-dependently increased longitudinal bone growth rate from 42 µm/day (vehicle) to 52 µm/day at the highest dose (P<0.0001) by tetracycline labeling at the proximal tibia, with parallel body-weight gain; total IGF-1 and bone-turnover markers were unaffected. Early evidence of skeletal anabolism.

PubMed

P Preclinical · bone mineral content

Svensson et al. 2000 — 12-week DXA bone study in rats (J Endocrinol)

Continuous SC infusion of ipamorelin (0.5 mg/kg/day, osmotic minipump, 12 weeks) in 13-week-old female Sprague-Dawley rats increased bone mineral content by DXA, comparable to GHRP-6 and recombinant GH at equivalent doses — the first evidence that ipamorelin's GH-releasing effect translates into measurable bone accretion.

PubMed

P Preclinical · glucocorticoid model

Andersen et al. 2001 — counteracting steroid catabolism in rats (Growth Horm IGF Res)

In 8-month-old female rats given methylprednisolone (9 mg/kg/day), concurrent ipamorelin (100 µg/kg 3× daily SC) over 3 months increased periosteal bone formation rate four-fold vs glucocorticoid-only animals and reversed steroid-induced loss of calf-muscle tetanic tension — positioning ipamorelin as a candidate against corticosteroid-induced osteoporosis and myopathy, a major unmet need.

PubMed

P Preclinical · GI motility

Greenwood-Van Meerveld et al. 2012 — gastric emptying (J Exp Pharmacol)

In a laparotomy / intestinal-manipulation rodent model of gastroparesis, ipamorelin (0.014–0.14 µmol/kg IV) significantly accelerated gastric emptying vs vehicle via ghrelin-receptor-coupled cholinergic excitatory pathways — the biological rationale that motivated the postoperative-ileus development program.

PubMed

B Phase II RCT · postoperative ileus

Beck et al. 2014 — Phase II RCT, n=117 (Int J Colorectal Dis)

Multicenter double-blind placebo-controlled RCT in 117 adults after bowel resection: IV ipamorelin 0.03 mg/kg BID on POD 1–7. Median time to first tolerated solid meal 25.3 h vs 32.6 h placebo (p=0.15 — not significant). AE incidence 87.5% vs 94.8% placebo; no serious drug-attributable signals. Well tolerated; primary efficacy endpoint not met. The largest published human efficacy trial of ipamorelin.

ClinicalTrials.gov

D Development · discontinuation

Helsinn Phase IIb (NCT01280344) — program discontinued

Helsinn Therapeutics (which acquired Sapphire Therapeutics in 2009) enrolled ~320 patients from May 2011 in a larger Phase IIb GI-recovery trial after bowel resection. The program was discontinued without published efficacy data, reportedly for business rather than safety reasons. The full development arc ran Novo Nordisk (1995–2007) → Sapphire (2007) → Helsinn (2009–2014).

NCT01280344

D Regulatory · status (2026)

Regulatory landscape — compounding reclassification (2026)

After the FDA moved ~19 commonly compounded peptides (including ipamorelin) to its Category 2 bulk-substance list in 2023, HHS Secretary RFK Jr. announced on 27 Feb 2026 that 14 of them — ipamorelin included — would be reclassified to Category 1, restoring 503A/503B compounding eligibility. As of mid-2026 no formal Federal Register rule had been published; ipamorelin remains not FDA-approved for any indication and requires a valid prescription.

FDA compounding

D Research program · gap

The central gap — no human body-composition RCT

As of 2026, no completed randomized controlled trial has evaluated ipamorelin's effects on body composition (lean/fat mass), bone density, or anti-aging outcomes in humans. The widely circulated body-composition and anti-aging claims derive from animal studies, GH-secretagogue class effects, and limited PD observations — not from prospective efficacy trials. Priority future work: 12–24-week DXA body-composition RCTs, polysomnographic sleep studies, GLP-1 lean-mass-preservation trials, and long-term safety registries.

ClinicalTrials.gov

Read-out signal

Ipamorelin occupies a paradoxical position: it is one of the best-characterized GH secretagogues at the receptor and pharmacokinetic level, with a uniquely clean selectivity profile and a benign tolerability record across its (short-duration) human exposure — yet its formal clinical development ended without a positive efficacy trial, and the body-composition, recovery, and anti-aging uses that dominate real-world practice have never been tested in a randomized human trial. The 2026 compounding reclassification, if formalized, lowers the access barrier without supplying the missing efficacy evidence. The most informative future trials are straightforward and overdue: randomized DXA body-composition studies (ipamorelin ± CJC-1295), polysomnographic sleep-architecture studies, lean-mass-preservation trials during GLP-1 weight loss, and a compounding-pharmacy real-world safety registry to characterize long-horizon effects and cancer incidence.

07 · Compare & contrast

Adjacent peptides.

08 · Evidence & references

Every claim, graded and sourced.

A · RCT / meta-analysis

B · Large cohort / consistent trial set

C · Small trial / mechanistic

P · Preclinical / animal

D · Expert / textbook / regulatory

Explore the ATLAS index

Ipamorelinthe first selective growth hormone secretagogue

Key facts & headline data.

How a selective secretagogue works.

GHS-R1a agonism · the calcium trigger

Selectivity · no cortisol, ACTH, or prolactin

Pulsatile release · physiology preserved

GHRH synergy · the dual-pathway pulse

Bone, muscle & GI-motility effects

Slow-wave sleep & the nocturnal GH pulse

Dosing ipamorelin.

Three per-pulse dose tiers & frequency interpolation.

Daily exposure interpolation · SC (practice-pattern)

Escalation, hold & stop logic.

Response & safety monitoring bundles.

Visual titration: from start to cycle-out.

Reconstitution & Dose Calculator

Stacking ipamorelin.

Clean selectivity; GH-axis & glucose caveats.

Contraindication reference

Suggested monitoring for ipamorelin protocols

Strong mechanism, real PK, no body-composition RCT.

Raun et al. 1998 — the first selective GHS (Eur J Endocrinol)

Svensson et al. 1999 — human PK/PD, 40 healthy males (J Endocrinol)

Johansen et al. 1999 — longitudinal bone growth in rats (Growth Horm IGF Res)

Svensson et al. 2000 — 12-week DXA bone study in rats (J Endocrinol)

Andersen et al. 2001 — counteracting steroid catabolism in rats (Growth Horm IGF Res)

Greenwood-Van Meerveld et al. 2012 — gastric emptying (J Exp Pharmacol)

Beck et al. 2014 — Phase II RCT, n=117 (Int J Colorectal Dis)

Helsinn Phase IIb (NCT01280344) — program discontinued

Regulatory landscape — compounding reclassification (2026)

The central gap — no human body-composition RCT

Adjacent peptides.

Every claim, graded and sourced.

More GH Axis peptides & tools.