Ipamorelin

Ipamorelin is a synthetic pentapeptide, a chain of five amino acids (Aib-His-D-2-Nal-D-Phe-Lys-NH2), that mimics the stomach hormone ghrelin. Ghrelin is the body's natural hunger signal, and one of its jobs is to tell the pituitary gland to release growth hormone (GH). Ipamorelin uses the same receptor and produces one sharp GH pulse per dose ¹.

The peptide was first described in 1998 in an industrial drug program built on earlier growth hormone releasing peptides ³. Its defining property is selectivity. In animal studies it released GH without raising ACTH, cortisol, or prolactin, even at doses more than 200 times the effective GH dose, while close relatives GHRP-6 and GHRP-2 do raise those hormones ³.

A short development history

A pharmaceutical program in the 2000s tested intravenous ipamorelin for postoperative ileus, a form of gut paralysis that follows bowel surgery. Rodent models produced positive results ⁵, but a randomized phase 2 trial in 117 patients showed no significant benefit over placebo ². Preclinical rat programs also studied bone growth and protection from glucocorticoid-induced muscle and bone loss ⁶.

Where it stands today

Ipamorelin is not approved for any indication. Reviews document contemporary use almost entirely through unregulated channels for body composition, recovery, and longevity ¹⁵. Community protocols typically use 100-300 mcg subcutaneously one to three times daily, often in 8-12 week cycles. Growth hormone releasing peptides are also WADA-prohibited in sport ¹⁹.

Ipamorelin's main action is straightforward: it impersonates ghrelin. Ghrelin is a hunger hormone made in the stomach that travels to the pituitary gland and tells it to release growth hormone. Ipamorelin binds the same docking site, the growth hormone secretagogue receptor type 1a (GHS-R1a), and each dose produces one burst of GH ¹.

In human volunteer studies, the GH peak arrived at about 40 minutes and then decayed back to baseline within hours. The peptide itself has a half-life of roughly 2 hours, with clearance of 0.078 L/h/kg and a steady-state volume of distribution of 0.22 L/kg. The plasma concentration for half-maximal GH stimulation (SC50) is 214 nmol/L, and the maximal GH production rate is 694 mIU/L/h ¹. Because one dose equals one short pulse, community protocols use multiple daily doses to generate several pulses across a day.

Selectivity: the defining feature

In conscious swine, ipamorelin released GH with an ED50 of 2.3 nmol/kg. It did not alter FSH, LH, prolactin, or TSH. Unlike GHRP-6 and GHRP-2, it did not raise ACTH or cortisol, even at doses more than 200-fold above the GH-releasing dose ³. Cortisol and prolactin elevations reported for the broader secretagogue class may therefore come from co-administered secretagogues or impurities rather than ipamorelin itself ¹⁵. That selectivity has only been confirmed in animals; no human study has verified it ³.

Secondary actions

The ghrelin receptor is not unique to the pituitary. It appears in gut, heart, lung, liver, kidney, pancreas, and fat tissue, and ipamorelin's secondary actions flow from that distribution:

• Gut motility: intravenous ipamorelin accelerated gastric emptying in a rat model of postoperative ileus and restored smooth-muscle contractility in tissue bath experiments through cholinergic excitatory neurons ⁵. The single human phase 2 trial did not show significantly faster gut recovery ².
• Pancreas: in pancreatic tissue from normal and diabetic rats, ipamorelin directly evoked insulin release, and the effect was blocked by calcium-channel and adrenergic drugs ¹⁰.
• Fat tissue: in mice, growth hormone secretagogues including ipamorelin increased food intake, serum leptin, and fat-pad mass through mechanisms independent of GH ⁹.
• Bone and muscle protection: in steroid-treated rats, ipamorelin preserved muscle force and raised bone formation rate four-fold ⁶, reduced hepatic urea-nitrogen synthesis by 20 percent ¹¹, and increased bone mineral content and longitudinal bone growth ⁷.
• Pain: ipamorelin dampened colon pain sensitivity and touch-induced pain in rats, and a ghrelin-receptor antagonist blocked the effect ¹³.

The literature on ipamorelin shows a split picture. The growth hormone releasing pharmacology is robust and replicated across species, while the body-composition and recovery outcomes it is marketed for have little or no human efficacy evidence ¹⁶.

Effects with human data

• Growth hormone pulse: in healthy volunteers, every dose produced one episodic GH release peaking at 0.67 hours, with dose-proportional kinetics and no ceiling within the tested range ¹.
• Postoperative gut recovery: in a randomized phase 2 trial of 117 bowel-resection patients, 0.03 mg/kg IV twice daily was well tolerated but did not significantly improve median time to first tolerated meal (25.3 vs 32.6 hours, p=0.15) against placebo ².
• Hormone selectivity (animal): no ACTH or cortisol release at more than 200 times the GH dose in swine, unlike GHRP-6 and GHRP-2 ³.

Effects from animal studies

• Bone: three independent rat programs showed dose-dependent longitudinal bone growth (42 to 52 µm/day over 15 days) ⁸, increased bone mineral content over 12 weeks ⁷, and a four-fold rise in periosteal bone formation rate in steroid-treated animals ⁶.
• Muscle and nitrogen balance: ipamorelin counteracted glucocorticoid-induced loss of maximum muscle force and normalized whole-body nitrogen balance in rats ⁶.
• Cancer cachexia: in ferrets, 1-3 mg/kg reduced cisplatin-induced delayed weight loss by about 24 percent, with no anti-nausea effect ¹².
• Adiposity (counterproductive signal): growth hormone secretagogues increased body weight, fat-pad mass, and serum leptin in mice through GH-independent mechanisms ⁹. Fat-loss marketing claims have no human data and run opposite to this preclinical direction ²⁰.

Effects with weak or no evidence

• Body composition in humans: reviews find no randomized human evidence for muscle gain or fat loss ¹⁶.
• Injury recovery: no human orthopedic outcomes have been published; the rationale rests on preclinical anti-catabolic data ²⁵.
• Fertility: one case series reports hormonal reversal and conception in premature ovarian insufficiency, but no dosing details or full text are available and the report is not verifiable ²⁴.

Ipamorelin protocols split into two worlds: trial-derived intravenous regimens and the subcutaneous community protocols extrapolated from human pharmacokinetics and animal data. No human trial supports the growth, recovery, or body-composition endpoints the compound is marketed for today ¹⁶.

Trial-derived regimens

The only randomized human efficacy trial tested postoperative ileus: 0.03 mg/kg intravenously twice daily for up to 7 days in bowel-resection patients ². The earlier human PK/PD dose-ranging study used single 15-minute infusions of 4.21 to 140.45 nmol/kg in healthy volunteers ¹. Neither defines a chronic outpatient subcutaneous schedule.

Community subcutaneous protocols

The community standard is 100-300 mcg subcutaneously two to three times daily for 8-12 week cycles, commonly as a single 200-300 mcg bedtime dose when frequency is trimmed. Daily totals are often built around 2-4 mcg/kg per injection, a range anchored to the swine GH-release ED50 of 2.3 nmol/kg ³. Stacked protocols add a GHRH analogue such as modified GRF 1-29 at 100 mcg per injection ²⁶.

Timing conventions rest on the pharmacokinetics: each dose generates one GH pulse peaking around 40 minutes with a roughly 2-hour half-life ¹. Practitioner guidance spaces doses at least 3 hours apart so the pituitary can recover between pulses, and favors fasted dosing because glucose and insulin blunt secretagogue-stimulated GH release. A bedtime dose aims at the natural nocturnal GH surge.

What not to extrapolate

Rat studies used far higher relative doses: 100 mcg/kg three times daily or 0.5 mg/kg/day ⁶. Allometric scaling from rodent mg/kg doses to humans is unreliable for these short peptides. The human IV trial benchmark, 0.03 mg/kg twice daily, equals roughly 2.2 mg per injection at 73 kg ², about ten times a typical community injection.

Cycles run 8-12 weeks with about 4 weeks off, though a minority of protocols use 5 days on and 2 days off. The longest controlled human exposure in the literature is 7 days ². The cycling section covers the rationale behind scheduled breaks.

Ipamorelin is supplied as a lyophilized (freeze-dried) powder that must be reconstituted before use. Reconstitution protocols use bacteriostatic water (0.9 percent benzyl alcohol) for multi-dose vials, which suits a peptide dosed repeatedly over days or weeks. Sterile water for injection is used for single-dose preparation or when benzyl alcohol sensitivity is a concern.

The diluent is drawn up and added slowly down the inside wall of the vial, then the vial is swirled gently until the solution clears. Shaking is avoided because vigorous agitation can damage the peptide. U-100 insulin syringes are commonly used for accurate microdose measurement. The interactive calculator below handles the volume math for any vial size, diluent volume, and target dose.

Storage and shelf life

• Before reconstitution: lyophilized ipamorelin is stored frozen at -20°C for long-term stability, or refrigerated at 2-8°C for months with desiccant, protected from light and moisture.
• After reconstitution: the solution is refrigerated at 2-8°C, with a typical use window of 14 to 28 days when reconstituted with bacteriostatic water. Freezing reconstituted solution is discouraged because freeze-thaw cycles degrade peptides and cause adsorption to container surfaces.
• Stability: ipamorelin is moderately resistant to degradation, with 60 to 80 percent of a dose recovered intact in urine and bile in rat studies ⁴, though it is cleared quickly in the body, with a terminal half-life around 2 hours in humans ¹.

Product quality is the dominant handling risk. Across 6,441 independent tests of gray-market peptide samples that included ipamorelin, 41.6 to 71.1 percent failed basic quality benchmarks depending on the standard applied, and about 15 percent carried measurable endotoxin ¹⁸. Sterile technique and third-party testing of each batch are routine parts of research practice.

There are no formal human drug-interaction trials for ipamorelin. The profile below is assembled from animal pharmacology, the single phase 2 trial, and class-level reports of growth hormone secretagogue use ¹⁵.

Pituitary GH stack partners

• GHRH analogues (sermorelin, tesamorelin, CJC-1295): these act on the GHRH receptor rather than ipamorelin's ghrelin receptor, so their effects add rather than overlap ¹⁴. The CJC-1295 plus ipamorelin pair is the most common stack in community protocols, typically 100 mcg of each per injection, and in a mouse model of glucocorticoid-induced muscle loss the combination improved maximum muscle force ²⁵.
• Other GHRPs (GHRP-2, GHRP-6, hexarelin): redundant ghrelin-receptor occupancy that adds the ACTH and cortisol liability ipamorelin lacks in animal studies ³.
• MK-677 (ibutamoren): an oral ghrelin mimetic with the same receptor target and its own cardiovascular and appetite profile; combining it with ipamorelin is redundant ¹⁶.
• Insulin and IGF-1 analogues: ipamorelin directly stimulates pancreatic insulin release in rat tissue ¹⁰, so combining with exogenous insulin or IGF-1 carries a theoretical additive hypoglycemia risk.

Metabolic and hormonal

• GLP-1 receptor agonists (semaglutide, tirzepatide): opposing appetite drives. Ipamorelin increases food intake and fat-pad mass in animal models ⁹, which works against GLP-1 fat-loss goals, and both compound classes perturb glucose handling ¹⁵.
• Corticosteroids: in animal models ipamorelin partially counteracted steroid-induced muscle wasting and nitrogen loss rather than interacting adversely ⁶, and methylprednisolone did not block the acute GH release ³⁰.
• Testosterone and HCG: explored as a body-composition adjunct in hypogonadal men and mechanistically non-conflicting ¹⁴.
• Somatostatin analogues (octreotide): somatostatin suppresses pituitary GH release, so these would blunt ipamorelin's primary effect (mechanistic extrapolation).

Cardiovascular and glucose drugs

• Beta-blockers, calcium-channel blockers, antimuscarinics: propranolol, diltiazem, and atropine each suppressed ipamorelin-evoked insulin release in rat pancreatic tissue ¹⁰. Whether they blunt GH output is unstudied.
• Insulin and sulfonylureas: theoretical additive hypoglycemia given the direct insulinotropic action ¹⁰.
• Prokinetics and opioids: relevant to the GI-motility research direction. Ipamorelin accelerates gastric emptying through cholinergic neurons in rodents ⁵, suggesting theoretical additivity with prokinetics and opposition with opioids.

Supplements and conditions

• Glucose-lowering supplements such as berberine, alpha-lipoic acid, cinnamon, and chromium carry a theoretical additive hypoglycemia signal ¹⁰.
• Yohimbine inhibited ipamorelin-evoked insulin release in rat pancreas ¹⁰.
• Ipamorelin's appetite-stimulating signal ⁹ works against stimulant-based appetite control.
• Conditions that warrant caution include active malignancy, diabetes or prediabetes, pituitary disorders, cardiovascular disease, and pregnancy, as covered in the safety section. Gastrointestinal resection may reduce efficacy because secretagogue-driven GH release is partly mediated through gastric ghrelin ²⁸.

No human study has established whether ipamorelin loses effect with continuous use, and cycling is a precautionary practice rather than a trial-validated requirement. The longest controlled human exposure is 7 days of intravenous dosing ², while community cycles run 8 to 12 weeks with about 4 weeks off.

Why scheduled breaks appear in protocols

• Receptor-level damping: after 15 days of three-times-daily dosing, rats showed a small but significant reduction in the GH response to a provocative ipamorelin dose (p<0.03), while GHRH response and pituitary GH content were unchanged. That pattern points to receptor-level attenuation rather than a depleted hormone pool ⁸.
• Somatotroph adaptation: 21 days of treatment in young female rats lowered basal intracellular GH and increased secretion-granule density while preserving the re-challenge response ³⁶. The pituitary appears to reset during off-periods.
• Ghrelin reservoir: growth hormone releasing peptides accumulate in the acid-secreting gastric mucosa, the site of ghrelin production, and GI-tract resection blunted GHRP-6-stimulated GH release by 60 to 70 percent while GHRH response stayed intact ²⁸. If a ghrelin-amplified component of the pulse fatigues, breaks may allow recovery.
• Cumulative class effects: chronic GH-axis stimulation in unregulated use is linked to prolactin and cortisol elevation, dysglycemia, fluid retention, and joint pain ¹⁵. Ipamorelin uniquely spares ACTH and cortisol in swine ³, but a scheduled break is the practical interval for detecting slow metabolic change.
• GH-independent fat gain: secretagogues increased feeding, fat-pad mass, and serum leptin in mice independent of GH ⁹. Appetite or weight drift is a direct reason to interrupt a long run.

Cycles seen in protocols

Pattern	Dosing	Cycle length	Break
5-on / 2-off	200-300 mcg SC 2-3x daily	Rolling, up to 16 weeks	2-4 weeks after each block
Continuous block	200-300 mcg SC 2x daily, or 300 mcg at bedtime	8-12 weeks	4 weeks
Low-dose nightly	150-200 mcg SC at bedtime	8-12 weeks	2-4 weeks

These are community schedules with no efficacy endpoint validated in trials.

Break signals reported in community use include loss of subjective sleep and recovery benefit, fasting-glucose creep ¹⁵, fluid retention ¹⁵, rising hunger or fat gain on a stable diet ⁹, and needing larger doses for the same effect. When a cycle seems to stop working, product variance is an alternative explanation: 41.6 to 71.1 percent of gray-market samples failed quality benchmarks across 6,441 tests ¹⁸.

Ipamorelin rarely appears alone in community protocols. The best-documented pairing is with a GHRH analogue, usually modified GRF 1-29, also called CJC-1295 without DAC.

Ipamorelin + CJC-1295 (modified GRF 1-29)

This is the canonical growth hormone stack. Ipamorelin opens the ghrelin receptor (GHS-R1a) ³, while CJC-1295 is a GHRH analogue that opens the GHRH receptor. The two signals converge on the pituitary from complementary directions, which is why the pairing is the most common growth hormone stack in community protocols. Typical community stacking runs 100-300 mcg of each in one subcutaneous administration, one to three times daily on an empty stomach ¹⁴. Animal support comes from a mouse model of glucocorticoid-induced muscle loss, where the combination significantly improved maximum muscle force ²⁵. No human efficacy trial has tested the stack ¹⁷.

Injury-recovery combinations

Community injury stacks commonly pair ipamorelin with BPC-157, TB-500, or GHK-Cu. None of these share ipamorelin's ghrelin-receptor mechanism, and no documented conflict exists, but the combinations also lack outcome studies.

Hormonal combinations

• Testosterone: growth hormone secretagogues are discussed as body-composition adjuncts in hypogonadal men, and the combination is mechanistically non-conflicting ¹⁴.
• HCG: no direct interaction data; plausible in the same hypogonadal context ¹⁴.

Combinations the research points away from

• GHRP-2, GHRP-6, or hexarelin: redundant ghrelin-receptor agonists that add the ACTH and cortisol release ipamorelin lacks in swine ³. Stacking them erases the selectivity advantage.
• MK-677: an oral ghrelin mimetic acting on the same receptor; redundant pharmacology with its own reported risk profile ¹⁶.
• GLP-1 agonists: ipamorelin's appetite-stimulating, adipogenic signal ⁹ works against the appetite-suppression goal of semaglutide-class drugs, and both perturb glucose handling ¹⁵.
• Insulin or IGF-1 LR3: direct pancreatic insulinotropic action ¹⁰ makes additive hypoglycemia a theoretical concern.

Ipamorelin has no FDA-approved indication, and no EMA, TGA, or MHRA marketing authorization appears in the reviewed literature. It circulates as an unregulated research peptide and through compounding channels outside approval pathways ¹⁵.

The formal development program took the compound through a multicenter, double-blind, placebo-controlled phase 2 trial for postoperative ileus (NCT00672074). Intravenous 0.03 mg/kg twice daily for up to 7 days was well tolerated, with adverse events in 87.5 percent versus 94.8 percent for placebo, but showed no significant efficacy, and no indication advanced toward approval ². A 2025 narrative review states that the FDA has banned ipamorelin due to safety concerns ²⁰. At a July 2026 Pharmacy Compounding Advisory Committee meeting, FDA scientists advised against expanded compounding access for the reviewed peptides, including ipamorelin, while the committee voted narrowly to recommend some compounds for compounding ²⁰.

Sports and anti-doping

Ipamorelin belongs to prohibited classes in sport. Growth hormone releasing peptides and secretagogues are on the WADA Prohibited List, with validated urinary detection methods at a minimum required performance level of 2 ng/mL in routine use ¹⁹. Detection coverage is broad:

• Urine LC-MS/MS screening and confirmation methods ²³.
• Dried blood spot analysis by UHPLC-HRMS at a 2.5 ng/mL detection limit ⁴².
• Urinary metabolite detection after the parent compound has cleared, including the ipamorelin (1-4) free acid found after nasal administration ²¹.
• Glycine-modified ipamorelin analogs identified in seized doping material represent deliberate screening-evasion chemistry that laboratories now target ²².

Possession and travel rules are jurisdiction-dependent, and gray-market product carries independent legal risk on top of sport rules ²⁰.

The best human tolerability data come from the phase 2 trial in bowel-resection patients: 0.03 mg/kg IV twice daily for up to 7 days was well tolerated, with adverse events actually lower than placebo (87.5 percent vs 94.8 percent) and no significant safety differences between groups ². That was an inpatient, short-duration, intravenous setting. Ambulatory subcutaneous use has no equivalent published data.

Common effects in community use

• Injection-site reactions: redness or stinging at the site, a documented class effect of self-injected GH-axis peptides ¹⁵.
• Headache, flushing, brief fatigue: commonly reported after doses.
• Appetite increase: expected from a ghrelin-receptor agonist. Ipamorelin increased food intake and serum leptin in mice through GH-independent mechanisms ⁹.

Uncommon and theoretical concerns

• Dysglycemia: ipamorelin directly evokes insulin release from rat pancreatic tissue via calcium-channel and adrenergic pathways ¹⁰, and dysglycemia is reported across the secretagogue class ¹⁵.
• Fat gain: in mice, ipamorelin increased fat-pad weight and relative body fat independent of GH ⁹. This runs opposite to fat-loss marketing claims.
• Muscle and joint aches, fluid retention: class effects of GH-IGF-1 axis peptides ¹⁵.
• Sleep changes: vivid dreams, lethargy, and mild sleep disturbance are commonly reported with evening dosing.
• Rare or theoretical: cardiovascular strain, insulin resistance, dyslipidemia, and psychiatric instability with chronic supraphysiologic use ¹⁷; hypersensitivity to a foreign peptide; worsening of unrecognized acromegaly.

The selectivity caveat

Ipamorelin's strongest selling point is that it lacks the cortisol and prolactin release seen with GHRP-2 and GHRP-6. That selectivity profile is solid in swine ³ but has not been confirmed in human studies. Class-level reviews still list prolactin and cortisol elevation as a secretagogue risk to watch ¹⁵.

Populations the literature flags

• Active malignancy: GH-IGF-1 axis stimulation raises mitogenic concerns, unproven but widely cautioned against ¹⁵.
• Pregnancy and breastfeeding: no human reproductive safety data exist ²⁰.
• Diabetes or impaired glucose tolerance: direct insulinotropic action plus GH-mediated insulin resistance ¹⁰.
• Proliferative diabetic retinopathy and uncontrolled cardiovascular disease: relative cautions ¹⁷.
• Competitive athletes: WADA prohibition ¹⁹.

Product quality: the largest concrete risk

Across 6,441 independent tests of gray-market peptide samples including ipamorelin, 41.6 to 71.1 percent failed quality benchmarks and about 15 percent carried measurable endotoxin ¹⁸. The adverse-event burden from injectable experimental peptides is unquantified by any surveillance system ²⁰, and the longest controlled human exposure is 7 days ². Community monitoring protocols track IGF-1 and fasting glucose at baseline and every 4-6 weeks, with prolactin and cortisol checks only if symptoms appear, reflecting ipamorelin's selectivity profile ³.