Side-by-side · Research reference

GHRP-2vsHGH Fragment 176-191

Side-by-side comparison across mechanism, dosage, evidence, side effects, administration, and stack synergies. Citations on every claim where available.

APhase 2HUMAN-REVIEWED15/42 cited

BAnimal-StrongHUMAN-REVIEWED28/59 cited

GHRP-2

Hexapeptide GHRP · Phase 2 (clinical diagnostic)

100–300 mcgPer doseBowers 1990

Phase 2Evidence levelBowers 1990 Sigalos 2018

~30 minHalf-lifeMalagón 1999

SQ · Multiple sites · 1–3×/day

HGH Fragment 176-191

GH Fragment · Pre-Clinical

50%Weight gain reductionNg 2000

~26 minHalf-life (est.)

No IGF-1 ↑GH axis impact

SQ · IP (animal) · Oral (tested)

01Mechanism of Action

Parameter

GHRP-2

HGH Fragment 176-191

Primary target

Ghrelin receptor (GHS-R1a) on anterior pituitaryBowers 1990

Beta-3 adrenergic receptors on adipocytesHeffernan 2001

Pathway

GHS-R1a → Gαq → Ca²⁺ → GH vesicle exocytosisBowers 2002

Fragment → β3-AR upregulation → Enhanced lipolytic sensitivityHeffernan 2001

Downstream effect

Strong GH pulse + IGF-1 elevation; appetite increase via ghrelin agonismBowers 2002

Increased lipolysis and beta-3 AR mRNA expression without IGF-1 axis activation

Feedback intact?

Yes, with somatostatin feedback active

N/A — does not interact with GH/IGF-1 axis

Origin

Synthetic hexapeptide; developed by Bowers/Tulane group in the 1980sBowers 1990

Synthetic peptide derived from hGH residues 176-191; AOD9604 includes N-terminal tyrosine (177-191)Cox 2015

Antibody development

—

Not reported in available studies

02Dosage Protocols

Parameter

GHRP-2

HGH Fragment 176-191

Standard dose

100–300 mcg per injectionBowers 1990

—

Frequency

1–3× per day

Once daily (animal models)

Lower / starter dose

50 mcg per dose

—

Evidence basis

Phase 2 + clinical diagnostic useBowers 1990

Animal studies only

Duration

8–12 weeks on / 4 off (anecdotal)

—

Reconstitution

Bacteriostatic water

—

Timing

Pre-sleep + fasted preferred

—

Half-life

~30 minMalagón 1999

—

Animal dose (oral)

—

500 mcg/kg body weightNg 2000

Obese Zucker rats, 19 days.

Animal dose (IP)

—

Not specified (14-day chronic administration)Heffernan 2001

Obese mice, daily IP injection.

Human equivalent dose

—

Not established — no published human RCTs

Duration tested

—

14–19 daysHeffernan 2001 Ng 2000

Detection window

—

50 pg/mL LOD in urine; stable metabolite extends detectionCox 2015

WADA-banned; anti-doping testing available.

Oral bioavailability

—

Demonstrated efficacy in animal oral administrationNg 2000

Potential for oral therapeutic development.

03Metabolic / Fat Loss Evidence

Parameter

GHRP-2

HGH Fragment 176-191

Primary fat target

—

Adipose tissue (general) — beta-3 AR mediated lipolysisHeffernan 2001

Weight gain reduction

—

50% reduction vs control (15.8 ± 0.6 g vs 35.6 ± 0.8 g)Ng 2000

Obese Zucker rats, 19 days oral administration.

Body fat reduction

—

Significant decrease in body weight and body fat in obese mice (14 days)Heffernan 2001

Lipolytic activity

—

Increased adipose tissue lipolytic activityNg 2000

Direct measurement in treated animals.

Beta-3 AR expression

—

Upregulated β3-AR mRNA in obese mice to lean-comparable levelsHeffernan 2001

Insulin sensitivity

—

No adverse effect — euglycemic clamp confirmedNg 2000

Contrasts with intact hGH diabetogenic effects.

IGF-1 impact

—

No elevation — fragment does not activate GH/IGF-1 axis

Beta-3 AR dependency

—

Effect abolished in β3-AR knockout miceHeffernan 2001

Confirms β3-AR as primary mechanism.

Route of administration

—

Efficacy demonstrated via oral and IP routesNg 2000 Heffernan 2001

Human evidence

—

None published — pre-clinical only

04Side Effects & Safety

Parameter

GHRP-2

HGH Fragment 176-191

Cortisol elevation

Mild but measurableBowers 1990

—

Prolactin elevation

Mild but measurable

—

Hunger

Strong appetite increase

—

Injection site reaction

Mild erythema

—

IGF-1 elevation

Strong; monitor with chronic high-dose use

—

Cancer risk

Contraindicated in active malignancy

—

Pregnancy / OB

Avoid

—

Insulin sensitivity

—

No adverse effects observed in euglycemic clamp (animal)Ng 2000

GH/IGF-1 axis

—

No activation — avoids diabetogenic effects of full GHNg 2000

Human safety data

—

Not available — no published human trials

WADA status

—

Banned as performance-enhancing drugCox 2015

Metabolic profile

—

Six metabolites identified; CRSVEGSCG most stableCox 2015

Detection window implications for doping control.

Absolute Contraindications

GHRP-2

·Active malignancy
·Pregnancy / breastfeeding

HGH Fragment 176-191

·Competitive athletes (WADA-banned)Cox 2015

Relative Contraindications

GHRP-2

·Untreated diabetes

HGH Fragment 176-191

·Absence of human safety data — experimental use only

05Administration Protocol

Parameter

GHRP-2

HGH Fragment 176-191

1. Reconstitution

Add 2 mL bacteriostatic water to 5 mg vial → 2.5 mg/mL.

Subcutaneous injection primary route in research context. Oral administration demonstrated efficacy in animal models at 500 mcg/kg.

2. Injection site

SQ — abdomen or thigh. Rotate sites.

Once daily dosing used in animal studies. Timing not specified; GH-independent mechanism suggests flexibility.

3. Timing

Pre-sleep + fasted preferred.

Animal protocols: 14–19 days. Human duration not established — no published trials.

4. Storage

Lyophilised: room temp, light-protected. Reconstituted: refrigerate ≤30 days.

Lyophilized peptide storage per standard peptide protocols. Metabolite stability suggests refrigerated reconstituted solution viable.

5. Needle

29–31G, 4–8 mm insulin syringe.

Detectable in urine via SPE-LC-MS at 50 pg/mL LOD. Extended detection window via stable metabolite CRSVEGSCG.Cox 2015

06Stack Synergy

GHRP-2

+ CJC-1295 (no DAC)

Strong

View CJC-1295 (no DAC) →

GHRP-2 + CJC-1295-no-DAC is a higher-amplitude alternative to the ipamorelin + CJC-1295 stack. GHRP-2 produces a stronger pulse but with cortisol + prolactin signal — choose when maximum GH amplitude is the goal and the side-effect tolerance is acceptable.

GHRP-2: 100–200 mcg SQ · pre-sleep
CJC-1295 (no DAC): 100 mcg SQ · same injection
Primary benefit: High-amplitude GH pulse, body composition

Bowers 1990 Teichman 2006

HGH Fragment 176-191

— no documented stacks