Side-by-side · Research reference

ACE-031vsGonadorelin

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

BFDA-ApprovedHUMAN-REVIEWED7/61 cited

ACE-031

ActRIIB-Fc Fusion · Phase 2 Halted

Phase 2Highest trial stage

2011Development halted

~58.4 kDaMolecular weightReichel 2025

SQ · Weekly dosing investigated

Gonadorelin

GnRH Analogue · Diagnostic & Therapeutic

90 minPulsatile interval

73%Ovulation restorationTadesse 2026

2–4 minPlasma half-life

IV / SQ · Pulsatile Pump (Therapeutic) · Single Bolus (Diagnostic)

01Mechanism of Action

Parameter

ACE-031

Gonadorelin

Primary target

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

GnRH receptors on anterior pituitary gonadotropes

Pathway

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

GnRH → Pituitary gonadotrope → LH/FSH secretion → Gonadal steroidogenesisSharma 2026

Downstream effect

Disinhibition of myogenic signaling, increased skeletal muscle mass and strength

Pulsatile LH/FSH release stimulates testicular testosterone or ovarian estradiol/progesterone synthesis; initiates folliculogenesis and spermatogenesisRobin 2026 Sharma 2026

Feedback intact?

—

Yes — pulsatile delivery preserves negative feedback loops; continuous exposure desensitizes receptors

Origin

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

Synthetic decapeptide (pGlu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH2) identical to native hypothalamic GnRH

Antibody development

—

02Dosage Protocols

Parameter

ACE-031

Gonadorelin

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

RCT / Expert consensus

Half-life

Days to weeks (Fc-fusion typical kinetics)

IgG1-Fc domain confers extended circulation time.

2–4 minutes (plasma)

Necessitates frequent pulsatile administration.

Duration investigated

12–24 weeks (trial cut short)

—

Diagnostic test (pituitary function)

—

100 mcg IV or SQ bolus

Measure baseline LH/FSH, then 30/60/90 min post-injection. Normal response: LH ≥2× baseline.

Therapeutic (hypothalamic hypogonadism)

—

5–20 mcg IV bolus every 90–120 minutes

Requires portable pulsatile pump. Dose individualized to achieve normal gonadotropin pulsatility.Robin 2026

Pulsatile interval

—

90 minutes (females) · 120 minutes (males)

Mimics physiological GnRH pulse frequency.

Route

—

IV preferred (therapeutic) · SQ acceptable (diagnostic)

Duration

—

Continuous until pregnancy achieved or fertility goals met

3–6 month courses typical for ovulation induction.

Alternative protocols

—

Exogenous gonadotropins (hCG/hMG) often preferred due to convenience vs pump requirement

03Metabolic / Fat Loss Evidence

Parameter

ACE-031

Gonadorelin

Fat loss mechanism

—

None — gonadorelin acts exclusively on reproductive axis

Indirect metabolic effects

—

Restoration of sex hormones may normalize body composition in hypogonadal states

Effect mediated by downstream testosterone/estradiol, not GnRH itself.

04Side Effects & Safety

Parameter

ACE-031

Gonadorelin

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

—

Injection site reaction

—

Erythema, irritation (pulsatile pump catheter site)

Headache

—

Common with bolus administration

Nausea / abdominal discomfort

—

Transient, dose-related

Ovarian hyperstimulation syndrome (OHSS)

—

Risk with ovulation induction protocols; monitor follicular development via ultrasound

Multiple gestation

—

Increased risk with fertility protocols (twins ~10–15%)

Anaphylaxis

—

Rare hypersensitivity reaction

Pump malfunction / infection

—

Mechanical failure or catheter-site infection with long-term IV pump use

Receptor desensitization

—

Continuous (non-pulsatile) exposure paradoxically suppresses gonadotropinsRobin 2026

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

Gonadorelin

·Pregnancy (except therapeutic infertility protocols)
·Hypersensitivity to gonadorelin or excipients
·Hormone-dependent tumors (prostate, breast) — risk of tumor stimulation via sex hormone elevation

Relative Contraindications

ACE-031

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

Gonadorelin

·Ovarian cysts or PCOS (monitor for OHSS)
·Pituitary adenoma or other sellar mass (may worsen with gonadotropin surge)

05Administration Protocol

Parameter

ACE-031

Gonadorelin

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.

Administer 100 mcg IV or SQ bolus. Draw baseline LH/FSH, then at 30, 60, 90 minutes. Normal response: LH ≥2× baseline, FSH modest rise. Blunted response suggests pituitary pathology; exaggerated response may indicate primary hypogonadism.

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

Requires programmable infusion pump with IV catheter. Set pulse interval to 90 min (females) or 120 min (males). Bolus dose 5–20 mcg per pulse. Pump worn continuously; catheter site rotated every 48–72 hrs to prevent infection.

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

Lyophilised gonadorelin reconstituted with sterile saline or provided diluent. Typically 0.8–3.2 mg dissolved in 8 mL for pump reservoir. Solution stable 7–14 days refrigerated.

4. Clinical trial route

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

For fertility protocols: ultrasound follicular tracking + serial estradiol/LH measurements. Adjust pulse dose to achieve mid-follicular LH 5–10 IU/L. Ovulation confirmed by progesterone rise or ultrasound.

5. Timing

—

Pulsatile therapy initiated at any point in cycle. Diagnostic test performed in morning (higher baseline LH). For ovulation induction, treatment begins early follicular phase.

06Stack Synergy

ACE-031

— no documented stacks

Gonadorelin

+ hCG (Human Chorionic Gonadotropin)

Multi-pathway

View hCG (Human Chorionic Gonadotropin) →

In hypogonadotropic hypogonadism protocols, gonadorelin restores pituitary LH/FSH pulsatility, while exogenous hCG directly stimulates Leydig cells (acting as LH mimetic) to maintain testosterone production. This dual approach ensures both central axis restoration and immediate gonadal steroidogenesis, preventing testicular atrophy during fertility treatment. hCG's longer half-life (24–36 hrs) complements gonadorelin's pulsatile short-acting profile.

Gonadorelin: 5–10 mcg IV every 120 min (pulsatile pump)
hCG: 1500–2000 IU SQ · 2–3× per week
Duration: 12–24 weeks for spermatogenesis induction
Primary benefit: Fertility restoration in hypothalamic hypogonadism with maintained testicular function