Side-by-side · Research reference

RetatrutidevsThymosin α-1

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

APhase 2Reviewed10/41 cited

BPhase 3Reviewed8/39 cited

Retatrutide

Triple-receptor agonist · Phase 3

1–12 mgWeekly doseJastreboff 2023

24.2%Body-weight ↓Jastreboff 2023

~6 daysHalf-life (est)

SQ · Abdomen · Once weekly

Thymosin α-1

Immune modulator · Approved (some countries)

1.6 mgPer doseIyer 2007

Phase 3Evidence levelIyer 2007 Camerini 2001

~2 hrHalf-life

SQ · 2× weekly · 6+ months for chronic indications

01Mechanism of Action

Parameter

Retatrutide

Thymosin α-1

Primary target

GLP-1R + GIPR + Glucagon receptor (triple agonism)Jastreboff 2023

Toll-like receptor 9 (TLR9) + T-cell maturation pathwayCamerini 2001

Pathway

Triple-receptor activation → ↑insulin (GLP-1+GIP), ↓gastric emptying, ↑lipid handling, ↑energy expenditure (glucagon component)Jastreboff 2023

TLR9 activation → ↑ IFN-α + IL-2 + IFN-γ → enhanced T-cell function + dendritic cell maturationIyer 2007

Downstream effect

Maximal weight loss across class. Glucagon component drives lipolysis and energy expenditure beyond GLP-1+GIP aloneJastreboff 2023

Restored T-cell function, improved viral clearance, anti-tumour adjuvant effectsIyer 2007

Feedback intact?

—

Origin

Synthetic peptide engineered for balanced affinity at three incretin / glucagon receptorsJastreboff 2023

Synthetic 28-AA peptide identical to natural Tα-1 isolated from thymus extractCamerini 2001

Antibody development

—

02Dosage Protocols

Parameter

Retatrutide

Thymosin α-1

Standard dose

12 mg / week (max efficacy)Jastreboff 2023

Phase 2 trial dose. Phase 3 dosing TBD.

—

Frequency

Once weekly

2× weekly (Mon/Thu typical)

Titration schedule

2 mg → 4 mg → 8 mg → 12 mg over 16 weeks

—

Evidence basis

Phase 2 trial; Phase 3 ongoingJastreboff 2023

Phase 3 + approved (35+ countries as Zadaxin)Iyer 2007

Duration

Indefinite for chronic indication (presumed)

6–12 months for chronic indications

Reconstitution

Investigational; not commercially available

Sterile water for injection per vial label

Timing

Any time of day

No specific time

Half-life

~6 days (estimated from class)

~2 hours plasma; tissue effect days

Standard dose (HBV/HCV)

—

1.6 mg SQ 2× weekly × 6–12 monthsIyer 2007

Lower / starter dose

—

0.8 mg per injection

04Side Effects & Safety

Parameter

Retatrutide

Thymosin α-1

GI symptoms

Nausea, vomiting, diarrhea (very common, dose-dependent)Jastreboff 2023

Rare nausea

Heart rate

↑ resting HR (3–7 bpm at 12 mg)Jastreboff 2023

—

Glucose handling

Glycemic improvement; rare hyperglycemia from glucagon component

—

Pancreatitis risk

Class warning

—

Thyroid C-cell tumours

Class warning (presumed)

—

Pregnancy / OB

Avoid (insufficient data)

Avoid

Injection site reaction

—

Erythema, mild discomfort

Fatigue

—

Common during initial weeks

Fever / flu-like

—

Mild interferon-like response possible

Autoimmune

—

Theoretical risk; caution in active autoimmune disease

Cancer risk

—

No signal — used as adjuvant in oncology

Absolute Contraindications

Retatrutide

·MTC personal or family history (presumed class effect)
·Pregnancy / breastfeeding

Thymosin α-1

·Pregnancy / breastfeeding
·Hypersensitivity to peptide
·Concurrent immunosuppressant therapy (transplant patients)

Relative Contraindications

Retatrutide

·Severe gastroparesis
·History of pancreatitis
·Severe cardiovascular disease (HR signal)

Thymosin α-1

·Active autoimmune disease
·Severe immunocompromised state without supervision

05Administration Protocol

Parameter

Retatrutide

Thymosin α-1

1. Reconstitution

Investigational peptide. Research vials reconstituted with bacteriostatic water per label.

Add 1 mL sterile water per 1.6 mg vial → 1.6 mg/mL.

2. Injection site

SQ — abdomen, thigh, or upper arm. Rotate weekly.

SQ — abdomen, thigh, or upper arm. Rotate sites.

3. Timing

Once weekly, same day.

2× weekly, e.g. Monday + Thursday.

4. Storage

Refrigerate 2–8 °C. Light-protected.

Lyophilised: refrigerate. Reconstituted: refrigerate, use within 24 h.

5. Needle

27–31G, 4–8 mm insulin syringe.