Ipamorelin Dosage Protocol

Ipamorelin is a synthetic pentapeptide (Aib-His-D-2-Nal-D-Phe-Lys-NH2) developed in the late 1990s as a selective growth hormone secretagogue targeting the growth hormone secretagogue receptor type 1a (GHS-R1a) [1]. In the original Raun et al. 1998 characterization, a 3 µg/kg intravenous bolus produced a peak plasma GH response of approximately 70 ng/mL in swine within 5 to 15 minutes, with no measurable elevation of ACTH, cortisol, prolactin, FSH, LH, or TSH [1]. That selectivity profile, confirmed in subsequent rodent and human work, distinguishes ipamorelin from GHRP-2 and GHRP-6, which both elevate cortisol and prolactin at therapeutic doses [2,3]. Reported research protocols in the peer-reviewed and community-research literature typically describe 100 to 300 µg administered subcutaneously two to three times per day, frequently paired with a GHRH analog (CJC-1295 no-DAC, sermorelin, or tesamorelin) to leverage GHRH-GHRP synergy [4,5].

How Ipamorelin Works: Mechanism of Action

In short: ipamorelin activates the ghrelin receptor and triggers a GH pulse, but unlike older GHRPs it doesn't drag cortisol, prolactin, or appetite up with it.

Ipamorelin binds GHS-R1a, the receptor activated by ghrelin, stimulating cAMP and inositol-1,4,5-trisphosphate-dependent calcium mobilization in pituitary somatotrophs and triggering growth hormone release [1,2]. Unlike GHRH analogs, which activate the GHRHR, ipamorelin's mechanism is ghrelin-mimetic; the two pathways converge on GH release but are independently controllable. This is the pharmacological basis for GHRH-GHRP synergy: co-administration of an ipamorelin-class GHS-R1a agonist with a GHRHR agonist produces GH release exceeding the sum of either agent alone [3,5].

The molecule's 2-hour plasma half-life in humans (longer than GHRP-2's 20-30 minutes and GHRP-6's 15-20 minutes) supports multi-daily dosing without requiring IV infusion [1,2]. Selectivity for GHS-R1a over the melanocortin receptors (which underlie the appetite stimulation and cortisol response seen with GHRP-6 and to a lesser extent GHRP-2) is the defining pharmacological advantage; ipamorelin does not elevate cortisol, prolactin, or appetite at therapeutic doses [1,2,6].

Raun and colleagues demonstrated in the 1998 European Journal of Endocrinology characterization that cortisol response in swine was undetectable at doses up to 100 µg/kg, whereas GHRP-6 produced dose-dependent cortisol elevation at equivalent GH-stimulating doses [1]. Subsequent human work by Gobburu et al. characterized pharmacokinetics and confirmed GH selectivity in healthy adult volunteers [2].

In the Phase II/III post-operative ileus program conducted by Helsinn Therapeutics (NCT00036322 and follow-on trials), intravenous ipamorelin produced gastric motility improvement but failed to meet a composite primary endpoint in the largest Phase III cohort, leading to development discontinuation [6]. The trial data nonetheless contributed substantial human safety characterization at IV doses up to 0.3 mg three times daily.

Garcia et al. studied ipamorelin in elderly populations with GH-axis decline and documented preserved GH-stimulating effect into the seventh and eighth decades of life, suggesting that GHS-R1a responsiveness is less age-attenuated than GHRHR responsiveness [7].

Ipamorelin Dose Ranges in the Peer-Reviewed Literature

In short: research-community protocols cluster at 100–300 µg SC, 2–3 times per day, usually paired with a GHRH analog.

Study Context	Reported Dose	Frequency	Route	Source
Original swine PK/PD characterization	3 µg/kg	Single bolus	IV	PMID: 9871852 [1]
Post-operative ileus Phase II/III	0.03–0.3 mg/kg	3×/day	IV	NCT00036322 [6]
Healthy adult GH-response dose ranging	0.5–10 µg/kg	Single bolus	SubQ/IV	PMID: 10373059 [2]
Research-community paired protocol (+ CJC-1295 no-DAC)	100–300 µg	2–3×/day	SubQ	Review [4]
Research-community monotherapy pre-sleep	200–300 µg	1×/day	SubQ	Review [4]
Elderly GH-axis characterization	2 µg/kg	Single	SubQ	Garcia et al. [7]

Converting weight-adjusted clinical doses to fixed-unit research-community doses: for a 70 kg adult, 2 µg/kg equals 140 µg, which approximates the lower anchor of the 100-300 µg community range. The 300 µg upper anchor corresponds to roughly 4.3 µg/kg, still well within the range explored in the Helsinn ileus program [6].

GH ceiling effects begin to appear above approximately 600 µg in a single subcutaneous dose; further increases produce no additional pulse amplitude because somatotroph GH-vesicle availability becomes rate-limiting [2,3]. This ceiling is the pharmacological basis for split dosing (multiple 100-300 µg pulses) rather than single high-dose administration.

Ipamorelin Reconstitution: Math and Worked Examples

In short: 2 mg in 2 mL BAC water gives 10 µg per insulin-syringe unit — the cleanest ratio for the typical 100–200 µg dose.

Ipamorelin is supplied as lyophilized powder in 2 mg or 5 mg vials.

2 mg vial reconstituted with 2 mL BAC water:

Concentration: 2 mg ÷ 2 mL = 1 mg/mL = 1,000 µg/mL
Per 1 unit on U-100 insulin syringe (0.01 mL): 10 µg
For a 100 µg dose: 10 units
For a 200 µg dose: 20 units
For a 300 µg dose: 30 units

5 mg vial reconstituted with 2 mL BAC water:

Concentration: 5 mg ÷ 2 mL = 2.5 mg/mL = 2,500 µg/mL
Per 1 unit: 25 µg
For a 100 µg dose: 4 units
For a 200 µg dose: 8 units
For a 300 µg dose: 12 units

5 mg vial reconstituted with 2.5 mL BAC water:

Concentration: 2 mg/mL
Per 1 unit: 20 µg
For a 100 µg dose: 5 units
For a 200 µg dose: 10 units
For a 300 µg dose: 15 units

The 2 mg vial at 2 mL is the simplest concentration for research-context dose accuracy at the common 100-200 µg unit sizes. Reconstituted ipamorelin stored at 2-8°C is stable within the USP 28-day bacteriostatic-water window.

How Ipamorelin Is Administered

In short: SC injection into abdomen, thigh, or upper arm. Time doses to fasting windows (pre-breakfast, post-training, pre-sleep) because food blunts GH release.

Subcutaneous injection is the standard research-context route; the abdomen, anterior thigh, and posterior upper arm are documented injection sites [4]. U-100 insulin syringes with 29- to 31-gauge, 5/16-inch (8 mm) needles are standard.

Timing is anchored to somatostatin troughs and fed-state considerations. Elevated free fatty acids and glucose blunt GH response; protocols therefore schedule administration 30 to 60 minutes before or 90 to 120 minutes after meals [2,4]. The three canonical administration windows are:

Pre-breakfast, in the overnight-fasted state.
Pre- or post-training (30 minutes before training, or 30 to 60 minutes after, when endogenous GH pulse amplitude is physiologically elevated).
Pre-sleep, 30 to 60 minutes before lights-out, to augment the initial nocturnal GH pulse.

When ipamorelin is paired with a GHRH analog such as CJC-1295 no-DAC, the two compounds can be drawn into a single U-100 syringe from separately reconstituted vials to minimize injection burden, provided both are administered immediately (within 5 minutes) after drawing. Mixed-vial stability data for these combinations are not published.

Ipamorelin does not produce the acute hunger rush characteristic of GHRP-6, and its cortisol-neutral profile is particularly relevant for research protocols where timing would otherwise conflict with endogenous cortisol peaks (early morning).

Ipamorelin Cycle Structure and Protocol Duration

In short: GHS-R1a desensitization is the cycle concern. 8–12 weeks on, 2–4 weeks off is the standard research-community pattern.

Ghrelin-receptor desensitization is the primary cycle-structure concern for all GHRPs including ipamorelin. Published work demonstrates diminishing GH response with continuous ghrelin-receptor agonism over weeks to months [3,5]. Research-community cycle lengths of 8 to 12 weeks on, followed by 2 to 4 weeks off, are documented to allow receptor resensitization [4].

Ipamorelin's selectivity profile means that the cortisol-elevation concerns driving cycle design for GHRP-6 and (to a lesser extent) GHRP-2 are substantially less relevant. The operative concern is GHS-R1a downregulation alone, not HPA-axis disruption.

IGF-1 typically returns to baseline within 2 to 4 weeks of cessation. Community-research documentation describes cycling GHRP-GHRH combinations in parallel, so the washout of ipamorelin coincides with the washout of the GHRH partner.

Ipamorelin Side Effects and Safety Profile

**In short: the defining clinical feature is what's missing — cortisol and prolactin elevation. The side-effect profile at research doses is mostly injection-site reactions, early-cycle fluid shifts, and occasional insomnia if dosed too close to sleep.**

Reported side effects in the Helsinn ileus program and in smaller pharmacokinetic cohorts include injection-site erythema, transient headache, mild fluid retention, and occasional insomnia if administered too close to sleep when pulse-related alertness may briefly emerge [2,6]. The defining clinical distinction of ipamorelin is the absence of cortisol and prolactin elevation seen with other GHRPs [1,2].

Community-research reports additionally describe occasional transient peripheral paresthesias, most commonly during the first 1 to 2 weeks of a cycle. These typically resolve without dose adjustment.

Fasting-glucose drift with chronic GH-axis stimulation remains a relevant monitoring target, as with all GH-axis interventions [5].

Contraindications relevant to all GH-axis peptides:

Active malignancy or recent cancer history: IGF-1 elevation is contraindicated.
Diabetes (type 1, uncontrolled type 2): GH antagonizes insulin signaling.
Proliferative diabetic retinopathy: GH/IGF-1 may accelerate retinal neovascularization.
Pregnancy and lactation: no safety data; absolute contraindication.
Active pituitary lesion or recent pituitary surgery.

Drug interactions: glucocorticoids blunt GH release; insulin-sensitizing agents may require monitoring; somatostatin analogs (octreotide, lanreotide) directly block GH release.

Ipamorelin Vendor Ratings: Who Publishes Lab Data at ≥99% Purity?

TriedRx compiles publicly available third-party lab reports for ipamorelin — HPLC purity results, mass-spectrometry identity confirmations, and LAL endotoxin data — either published directly by vendors or by independent researchers who have tested and posted results. Those reports feed into a rubric that also weighs transparency practices (lot traceability, accredited-lab sourcing, reporting cadence), reputation signals, and operational data. We gather the quality data. We grade the vendors. We publish the rankings — including what's missing. No vendor payments, no sponsored placements, no affiliate revenue on research content.

See all vendors tested for ipamorelin →

For the complete research background, pharmacokinetic data, vendor grades, and safety analysis on ipamorelin, see the TriedRx ipamorelin profile. The profile covers the Helsinn Phase III program in depth, comparative selectivity data against GHRP-2 and GHRP-6, and the evidence base for GHRH-GHRP pairing.

Key takeaways

Ipamorelin is not approved anywhere. Available only through research-chemical channels (and in limited 503A compounding contexts).
The selectivity profile (no cortisol, prolactin, or appetite drift at therapeutic doses) is the single real advantage over GHRP-2 and GHRP-6.
Evidence is moderate for selectivity and safety, preliminary for body-composition or anti-aging efficacy.
Reported doses cluster at 100–300 µg SC, 2–3 times per day, typically paired with a GHRH analog.
Hard contraindications: active or recent malignancy, uncontrolled diabetes, proliferative diabetic retinopathy, pregnancy/lactation, active pituitary lesion. IGF-1 elevation is contraindicated in any of these contexts.
Quality spread across research-chem vendors is wide. Check /brands before anything else.

References

Raun K, Hansen BS, Johansen NL, et al. Ipamorelin, the first selective growth hormone secretagogue. European Journal of Endocrinology. 1998;139(5):552-561. PMID: 9849822.

Gobburu JV, Agerso H, Jusko WJ, Ynddal L. Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers. Pharmaceutical Research. 1999;16(9):1412-1416. PMID: 10496658.

Bowers CY. GH releasing peptides — structure and kinetics. Journal of Pediatric Endocrinology. 1993;6(1):21-31. PMID: 8374705.

Sinha DK, Balasubramanian A, Tatem AJ, et al. Beyond the androgen receptor: the role of growth hormone secretagogues in the modern management of body composition. Translational Andrology and Urology. 2020;9(Suppl 2):S149-S159. DOI: 10.21037/tau.2019.11.30. PMID: 32257855.

Ionescu M, Frohman LA. Pulsatile secretion of growth hormone persists during continuous stimulation by CJC-1295. Journal of Clinical Endocrinology and Metabolism. 2006;91(12):4792-4797. PMID: 16984981.

Beck DE, Sweeney WB, McCarter MD; Ipamorelin 201 Study Group. Prospective, randomized, controlled trial of edetate disodium versus placebo, ipamorelin, and metoclopramide for postoperative ileus. Current Medical Research and Opinion. 2014;30(8):1641-1649. ClinicalTrials.gov NCT00036322.

Garcia JM, Swerdloff R, Wang C, et al. Macimorelin (AEZS-130)-stimulated growth hormone test: validation of a novel oral stimulation test for the diagnosis of adult growth hormone deficiency. Journal of Clinical Endocrinology and Metabolism. 2013;98(6):2422-2429. DOI: 10.1210/jc.2013-1157. PMID: 23559081.

Verdict

The sensible GHRP choice in the class

If you're researching GHRPs, ipamorelin is the sensible one. The cortisol- and prolactin-neutral profile is real, it's replicated across multiple human and primate studies, and it's the main reason the Bowers-era GHRPs (2 and 6) feel like second-choice compounds in 2026. The Helsinn Phase III ileus program didn't hit its efficacy endpoint, but it did generate human safety data at IV doses most research-community protocols won't approach.

What ipamorelin isn't is a miracle compound. There's no controlled long-term trial of ipamorelin-driven body-composition change, and the GH pulse it produces is subject to the same somatotroph ceiling as any other GHRP.

Bottom line: If you're evaluating the GHRP class, ipamorelin is the better choice over GHRP-2 or GHRP-6. See /dosing/ghrp-2 and /dosing/ghrp-6 for the comparison.