Side-by-side · Research reference

ACE-031vsGHRP-2

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

APhase 2HUMAN-REVIEWED10/44 cited

BPhase 2HUMAN-REVIEWED15/42 cited

ACE-031

ActRIIB-Fc Fusion · Phase 2 Halted

Phase 2Highest trial stage

2011Development halted

~58.4 kDaMolecular weightReichel 2025

SQ · Weekly dosing investigated

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

01Mechanism of Action

Parameter

ACE-031

GHRP-2

Primary target

Myostatin, GDF11, activin A — TGF-β superfamily ligands

Ghrelin receptor (GHS-R1a) on anterior pituitaryBowers 1990

Pathway

Soluble decoy receptor binds circulating myostatin/TGF-β ligands → prevents ActRIIB activation → SMAD2/3 pathway inhibition

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

Downstream effect

Disinhibition of myogenic signaling, increased skeletal muscle mass and strength

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

Feedback intact?

—

Yes, with somatostatin feedback active

Origin

Recombinant fusion protein: human ActRIIB extracellular domain + IgG1-Fc fragmentReichel 2025

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

Antibody development

—

02Dosage Protocols

Parameter

ACE-031

GHRP-2

Clinical dosing

Weekly or biweekly SQ injections (exact doses undisclosed pre-halt)

Phase 2 DMD trial protocol not fully published.

—

Black market products

Variable purity; 12/14 tested products contained target protein plus contaminantsReichel 2025

SDS-PAGE revealed multiple protein bands; quality control absent.Reichel 2025

—

Evidence basis

Phase 2 trial discontinued — incomplete dataset

Phase 2 + clinical diagnostic useBowers 1990

Half-life

Days to weeks (Fc-fusion typical kinetics)

IgG1-Fc domain confers extended circulation time.

~30 minMalagón 1999

Duration investigated

12–24 weeks (trial cut short)

—

Standard dose

—

100–300 mcg per injectionBowers 1990

Frequency

—

1–3× per day

Lower / starter dose

—

50 mcg per dose

Duration

—

8–12 weeks on / 4 off (anecdotal)

Reconstitution

—

Bacteriostatic water

Timing

—

Pre-sleep + fasted preferred

04Side Effects & Safety

Parameter

ACE-031

GHRP-2

Epistaxis (nosebleeds)

Significant incidence in Phase 2 DMD trial — primary safety signal

—

Telangiectasia

Dilated capillaries / spider veins observed

—

Vascular abnormalities

Mechanism: ActRIIB/ALK1 pathway disruption affects vascular homeostasis

—

Injection site reactions

Local erythema, induration (biologics class effect)

—

Antibody development

Potential for anti-drug antibodies (Fc-fusion proteins); incidence not reported

—

Black market contaminants

12/14 tested products contained multiple unidentified proteins alongside ACE-031Reichel 2025

—

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

Absolute Contraindications

ACE-031

·History of vascular disorders (epistaxis, telangiectasia, HHT)
·Pregnancy (TGF-β pathway critical for fetal development)
·Active malignancy (myostatin inhibition may affect tumour growth)
·Use of non-pharmaceutical grade ACE-031 (contamination risk)Reichel 2025

GHRP-2

·Active malignancy
·Pregnancy / breastfeeding

Relative Contraindications

ACE-031

·Coagulation disorders or anticoagulant use (epistaxis risk)
·Hereditary hemorrhagic telangiectasia (HHT) family history
·Cardiovascular disease (vascular remodeling effects unknown)

GHRP-2

·Untreated diabetes

05Administration Protocol

Parameter

ACE-031

GHRP-2

1. Pharmaceutical status

ACE-031 is not FDA-approved or commercially available. Phase 2 development was discontinued in 2011 due to safety concerns. Any ACE-031 on the black market is unregulated research chemical.

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

2. Black market quality

12 of 14 tested black market ACE-031 products contained the target protein but also carried multiple unidentified protein contaminants detectable by SDS-PAGE. Two products contained no ACVR2B-immunoreactive material.Reichel 2025

SQ — abdomen or thigh. Rotate sites.

3. Detection in sport

ACE-031 is prohibited under WADA S4.3 (Myostatin Inhibitors). Gel electrophoresis and Western blotting using ACVR2B-specific antibodies can detect the ~58.4 kDa protein in biological samples.Reichel 2025

Pre-sleep + fasted preferred.

4. Clinical trial route

Phase 2 protocol used subcutaneous injections at weekly or biweekly intervals. Exact dosing protocols remain unpublished.

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

5. Needle

—

29–31G, 4–8 mm insulin syringe.

06Stack Synergy

ACE-031

— no documented stacks

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