Side-by-side · Research reference

ACE-031vsTirzepatide

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-ApprovedFlagship14/45 cited

ACE-031

ActRIIB-Fc Fusion · Phase 2 Halted

Phase 2Highest trial stage

2011Development halted

~58.4 kDaMolecular weightReichel 2025

SQ · Weekly dosing investigated

Tirzepatide

GIP+GLP-1 Dual Agonist · FDA-Approved

2.5–15 mgWeekly doseZEPBOUND (tirzepatide) injecti 2023

20.9%Body-weight ↓Jastreboff 2022

~5 daysHalf-lifeZEPBOUND (tirzepatide) injecti 2023

SQ · Abdomen / thigh / arm · Once weekly

01Mechanism of Action

Parameter

ACE-031

Tirzepatide

Primary target

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

GIP receptor (GIPR) + GLP-1 receptor (GLP-1R)Frias 2018

Pathway

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

Dual GIPR/GLP-1R agonism → ↑insulin (glucose-dependent), ↓glucagon, ↓gastric emptying, ↓appetite, ↑energy expenditure (via GIP component)Jastreboff 2022 Frias 2018

Downstream effect

Disinhibition of myogenic signaling, increased skeletal muscle mass and strength

Profound glycemic improvement and weight reduction; cardiometabolic benefitsJastreboff 2022

Feedback intact?

—

Glucose-dependent insulin release preserves physiological feedback

Origin

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

39-AA peptide with C-20 fatty-acid acylation. Single molecule with balanced GIP + GLP-1 affinityFrias 2018

Antibody development

—

02Dosage Protocols

Parameter

ACE-031

Tirzepatide

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

FDA-approved · Phase 3 RCTs (SURMOUNT, SURPASS)Jastreboff 2022 ZEPBOUND (tirzepatide) injecti 2023

Half-life

Days to weeks (Fc-fusion typical kinetics)

IgG1-Fc domain confers extended circulation time.

~5 days (116 h)ZEPBOUND (tirzepatide) injecti 2023

Duration investigated

12–24 weeks (trial cut short)

—

Standard dose (T2D)

—

5–15 mg / weekZEPBOUND (tirzepatide) injecti 2023

Standard dose (weight)

—

5, 10, or 15 mg / week (titrated)ZEPBOUND (tirzepatide) injecti 2023 Jastreboff 2022

Titration schedule

—

2.5 mg → +2.5 mg every 4 weeks → 15 mg max

Slower titration mitigates GI side effects.

Duration

—

Indefinite for chronic indication

Reconstitution

—

Pre-filled commercial pen. Research vial: bacteriostatic water per label.

Timing

—

Once weekly, any time of day

04Side Effects & Safety

Parameter

ACE-031

Tirzepatide

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

—

GI symptoms

—

Nausea, vomiting, diarrhea (common, dose-dependent)Jastreboff 2022

Injection site reaction

—

Mild erythema, pruritus

Pancreatitis risk

—

Rare; discontinue if suspectedZEPBOUND (tirzepatide) injecti 2023

Thyroid C-cell tumours

—

Boxed warning — contraindicated in MEN2 / MTC historyZEPBOUND (tirzepatide) injecti 2023

Hypoglycemia

—

Low as monotherapy; risk with sulfonylureas / insulin

Gallbladder events

—

Increased cholelithiasis

Pregnancy / OB

—

Contraindicated

Diabetic retinopathy

—

Rapid glycemic improvement may transiently worsen

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

Tirzepatide

·MTC personal or family history; MEN2
·Pregnancy / breastfeeding
·Hypersensitivity to tirzepatide

Relative Contraindications

ACE-031

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

Tirzepatide

·Severe gastroparesis
·History of pancreatitis
·Diabetic retinopathy

05Administration Protocol

Parameter

ACE-031

Tirzepatide

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.

Commercial: pre-filled pen / vial. Research lyophilised: bacteriostatic water per label.

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, thigh, or upper arm. Rotate weekly.

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

Once weekly, same day. Day change allowed if ≥3 days separate doses.

4. Clinical trial route

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

Refrigerate 2–8 °C unopened. Room temp ≤30 °C up to 21 days after first use.

5. Needle

—

Pen-supplied. Research vial: 27–31G insulin syringe.