Side-by-side · Research reference

IGF-1 LR3vsThymalin

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

AAnimal-StrongHUMAN-REVIEWED10/58 cited

BHuman-MechanisticAUTO-DRAFTED12/40 cited

IGF-1 LR3

IGF-1 Analogue · Research

3–10×Potency vs IGF-I

Low IGFBPBinding affinity

ResearchStatus

Research only · SQ typical in animal models

Thymalin

Immune restorer · Russian peptide bioregulator

5–10 mgPer cycle doseKhavinson 2002

HumanMechanisticKhavinson 2002

HoursHalf-life (est)

IM · Daily for 5–10 days · 1-2×/year

01Mechanism of Action

Parameter

IGF-1 LR3

Thymalin

Primary target

IGF-1 receptor (IGF-1R)McTavish 2009

T-cell precursors + thymus-axis maturation pathwayKhavinson 2002

Pathway

IGF-1R → IRS-1 → PI3K/Akt → Cell proliferation, protein synthesis, anti-apoptosisMuhlbradt 2009

Modulation of T-cell differentiation + thymic hormone restoration in age-involuted thymusKhavinson 2002

Downstream effect

Enhanced cell proliferation, muscle anabolism, inhibition of apoptosis, increased telomerase activity

Restored T-cell populations, improved immune surveillance, reduced infection rates in elderlyKhavinson 2002

Feedback intact?

No — exogenous IGF analogue bypasses GH-mediated regulation

—

Origin

Synthetic 83-AA analogue: 13-AA N-terminal extension + Arg substitution at position 3

Polypeptide fraction isolated from calf thymus extractKhavinson 2002

Antibody development

—

02Dosage Protocols

Parameter

IGF-1 LR3

Thymalin

Research dose (animal models)

Variable by protocol and species

In vivo murine atherosclerosis studies used sustained delivery.

—

In vitro typical concentration

10–1000 ng/mLThomas 2007

Dose-dependent effects on follicle growth and estradiol production.

—

Half-maximal stimulation

0.6 nM LR3 vs 1.5 nM native IGF-1Price 2004

2.5-fold greater potency in lung fibroblast proliferation.

—

Evidence basis

Animal / in vitro only

Russian clinical + in vitroKhavinson 2002

Human use

Not FDA-approved; no published human trials

—

Standard dose

—

5–10 mg / day IM × 5–10 daysKhavinson 2002

Frequency

—

Once daily during cycle

Lower / starter dose

—

2.5 mg / day

Duration

—

5–10 day cycles, 1–2× per year

Reconstitution

—

Saline or bacteriostatic water

Timing

—

Morning preferred

Half-life

—

Hours (estimated)

03Metabolic / Fat Loss Evidence

Parameter

IGF-1 LR3

Thymalin

Mechanism

IGF-1R activation → lipolytic signaling; secondary to anabolic effects

—

Direct lipolytic evidence

Minimal — primarily anabolic/anti-apoptotic in literature

—

Atherosclerotic plaque effects

Reduced stenosis and core size in ApoE-KO micevon 2011

Plaque stabilization via vSMC phenotype modulation, not direct fat loss.

—

Human data

None published

—

04Side Effects & Safety

Parameter

IGF-1 LR3

Thymalin

Hypoglycemia risk

Theoretical — IGF-1 analogues can lower blood glucose

—

Excessive cell proliferation

Mitogenic signaling; theoretical tumor promotion risk

—

Telomerase activation

2–10-fold increase in prostate cancer cells (PC-3, DU-145, LAPC-4)Wetterau 2003

Critically involved in cancer cell immortalization.

—

Oocyte degeneration

Increased oocyte degeneration at high doses (≥1000 ng/mL) in bovine folliclesThomas 2007

—

Unregulated anabolism

Bypasses physiological GH/IGF-1 feedback; no pulsatility control

—

Unknown human safety profile

No published human trials; safety data absent

—

Injection site reaction

—

Mild erythema at IM site

Allergic reaction

—

Rare hypersensitivity to bovine-derived polypeptide

Autoimmune flare

—

Theoretical risk in active autoimmune disease

Long-term safety

—

Limited Western data

Pregnancy / OB

—

Avoid

Absolute Contraindications

IGF-1 LR3

·Active malignancy or history of cancer
·Not approved for human use

Thymalin

·Pregnancy / breastfeeding
·Bovine protein hypersensitivity

Relative Contraindications

IGF-1 LR3

·Diabetes or glucose intolerance
·Family history of cancer

Thymalin

·Active autoimmune disease
·Concurrent immunosuppressant therapy

05Administration Protocol

Parameter

IGF-1 LR3

Thymalin

1. Research use only

IGF-1 LR3 is not FDA-approved for human use. All administration data derives from animal or in vitro studies.

Add 1–2 mL saline or bacteriostatic water per 10 mg vial.

2. Typical research route

Subcutaneous or intraperitoneal injection in animal models. In vitro: added directly to culture medium at concentrations of 10–1000 ng/mL.Thomas 2007

Intramuscular — deltoid or gluteal. Rotate sites.

3. Reconstitution (research)

Lyophilised powder reconstituted in sterile water or buffered saline per manufacturer protocol. Store at 2–8 °C after reconstitution.

Morning preferred during cycle.

4. Stability

Enhanced stability vs native IGF-1 due to reduced IGFBP binding; exact half-life in vivo not fully characterized in humans.

Lyophilised: refrigerate, light-protected. Reconstituted: use immediately.

5. Needle

—

23–25G, 25–38 mm IM needle.

06Stack Synergy

IGF-1 LR3

+ GHRP-6

Multi-pathway

View GHRP-6 →

GHRP-6 stimulates endogenous GH release, which drives hepatic IGF-1 synthesis. IGF-1 LR3 provides exogenous, IGFBP-resistant IGF signaling. Combining upstream GH stimulation with downstream IGF receptor activation creates a dual-pathway anabolic effect. However, this bypasses natural feedback and carries compounded mitogenic risk.

GHRP-6: 100–200 mcg SQ · 2–3× daily
IGF-1 LR3: Research doses variable · post-workout typical in animal models
Note: Research context only — no human protocols exist
Primary benefit: Theoretical maximal anabolic signaling (GH + IGF axes)

+ Ipamorelin

Multi-pathway

View Ipamorelin →

Ipamorelin (selective GHRP) stimulates pulsatile GH release without cortisol/prolactin elevation. IGF-1 LR3 directly activates IGF-1R independent of GH. This stack targets both upstream (GH secretion) and downstream (IGF receptor) nodes but eliminates physiological feedback, raising safety concerns around unchecked proliferation.

Ipamorelin: 200–300 mcg SQ · evening
IGF-1 LR3: Research doses only · timing variable
Caution: No human data; animal/in vitro only
Primary benefit: Dual-axis anabolic signaling (theoretical)

Thymalin

+ Thymosin α-1

Moderate

View Thymosin α-1 →

Thymalin is a polypeptide complex; Thymosin α-1 is a single purified peptide. Both target the thymus-axis but at different levels — Thymalin restores broad thymic signaling; Tα-1 provides a specific molecular activator. Anecdotally combined for elderly immune support.

Thymalin: 5–10 mg IM · daily × 7 days
Thymosin α-1: 1.6 mg SQ · 2× weekly during the cycle
Primary benefit: Broad thymic restoration + targeted immune activation

Khavinson 2002 Camerini 2001