Larazotide vs Thymosin Beta-4 Fragment (TB4-Frag 17-23)
A neutral, side-by-side comparison of two healing & recovery peptides — their mechanisms, dosing ranges, administration routes, side effects, and research evidence. For research and educational purposes only.
Larazotide
Larazotide (AT-1001) is a synthetic octapeptide that acts as a tight junction regulator — it competitively blocks zonulin, the primary physiological driver of intestinal permeability ('leaky gut'). It is one of the few compounds studied in human clinical trials specifically for tight junction dysfunction, with Phase 2 data in celiac disease demonstrating reduced intestinal permeability and symptom improvement even in the presence of ongoing gluten exposure.
Full profileThymosin Beta-4 Fragment (TB4-Frag 17-23)
The heptapeptide fragment (amino acids 17–23) of full thymosin beta-4, sequence Ac-LKKTETQ. This sequence is the active actin-binding domain responsible for TB-500's tissue repair properties. Shorter molecular weight than TB-500 enables more targeted delivery while retaining identical mechanism of action on G-actin regulation and tissue repair signaling.
Full profile| Larazotide | Thymosin Beta-4 Fragment (TB4-Frag 17-23) | |
|---|---|---|
| Category | Healing & Recovery | Healing & Recovery |
| Also known as | Larazotide acetate, AT-1001, INN-202 | TB4 fragment 17-23, TB-500 active peptide, LKKTETQ, thymosin beta-4 fragment, Ac-LKKTETQ |
| Evidence | FDA-approved | Research-stage |
| Dosing range | 0.25mg–1mg mg, 3x daily (before meals) | 250mcg–1mg mcg–mg, 2–3x weekly |
| Administration | Oral (capsule), Subcutaneous injection (research use) | Subcutaneous injection, Intramuscular injection |
| Key side effects | Headache (most commonly reported adverse event in trials), Nausea (mild), Generally well-tolerated — adverse event rate similar to placebo in clinical trials | Injection site irritation, Mild fatigue (transient), Potential headache, Generally well-tolerated in research applications |
| Cited sources | 3 references | 2 references |
Key differences
- Evidence level differs: Larazotide is fda-approved, while Thymosin Beta-4 Fragment (TB4-Frag 17-23) is research-stage.
- Administration: Larazotide — Oral (capsule), Subcutaneous injection (research use); Thymosin Beta-4 Fragment (TB4-Frag 17-23) — Subcutaneous injection, Intramuscular injection.
- Dosing units differ: Larazotide is dosed in mg, Thymosin Beta-4 Fragment (TB4-Frag 17-23) in mcg–mg — they operate at different scales.
- Frequency: Larazotide is typically 3x daily (before meals); Thymosin Beta-4 Fragment (TB4-Frag 17-23) is 2–3x weekly.
- Research depth: this profile cites 3 sources for Larazotide vs 2 for Thymosin Beta-4 Fragment (TB4-Frag 17-23).
How each works
Larazotide
Zonulin upregulation disrupts the tight junction proteins occludin and claudin, allowing paracellular passage of antigens, LPS, and inflammatory triggers into systemic circulation. Larazotide acts as a tight junction agonist by competitively displacing zonulin from its receptor and directly stabilizing tight junction complexes. The Phase 2b CeD trial (N=342) showed larazotide reduced the ratio of lactulose/mannitol (L/M ratio, standard intestinal permeability marker) and improved GI symptom scores versus placebo in actively-challenged celiac patients.
Thymosin Beta-4 Fragment (TB4-Frag 17-23)
The LKKTETQ sequence was identified in 1994 as the minimum active fragment of thymosin beta-4 responsible for its actin-sequestering and tissue repair activity. This heptapeptide competes with actin monomer binding proteins, promoting cell migration, angiogenesis, and wound healing. Studies confirm it recapitulates the key bioactivity of full TB4 in cell migration and collagen deposition assays.
This comparison aggregates public research and structured profile data for informational purposes only. It is not medical advice and does not recommend either compound for human use. Consult a qualified healthcare provider before considering any peptide.