Thymosin Beta-4 Fragment (TB4-Frag 17-23) vs Vasoactive Intestinal Peptide (VIP)
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.
Thymosin 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 profileVasoactive Intestinal Peptide (VIP)
28-amino acid neuropeptide found throughout the CNS, gut, and immune system. Functions as a potent anti-inflammatory, vasodilator, and neurotrophic factor. Research applications include CIRS (Chronic Inflammatory Response Syndrome), pulmonary arterial hypertension, autoimmune conditions, and gut motility disorders. Intranasal administration is most studied for CIRS and neuroinflammatory conditions.
Full profile| Thymosin Beta-4 Fragment (TB4-Frag 17-23) | Vasoactive Intestinal Peptide (VIP) | |
|---|---|---|
| Category | Healing & Recovery | Healing & Recovery |
| Also known as | TB4 fragment 17-23, TB-500 active peptide, LKKTETQ, thymosin beta-4 fragment, Ac-LKKTETQ | VIP, vasoactive intestinal polypeptide, PHM-27 |
| Evidence | Research-stage | Investigational (in trials) |
| Dosing range | 250mcg–1mg mcg–mg, 2–3x weekly | 25mcg–100mcg mcg, Daily intranasal or 1–2x weekly subcutaneous |
| Administration | Subcutaneous injection, Intramuscular injection | Intranasal spray, Subcutaneous injection, Inhalation (nebulized) |
| Key side effects | Injection site irritation, Mild fatigue (transient), Potential headache, Generally well-tolerated in research applications | Facial flushing, Transient hypotension, Nasal irritation (intranasal route), Tachycardia |
| Cited sources | 2 references | 2 references |
Key differences
- Evidence level differs: Thymosin Beta-4 Fragment (TB4-Frag 17-23) is research-stage, while Vasoactive Intestinal Peptide (VIP) is investigational (in trials).
- Administration: Thymosin Beta-4 Fragment (TB4-Frag 17-23) — Subcutaneous injection, Intramuscular injection; Vasoactive Intestinal Peptide (VIP) — Intranasal spray, Subcutaneous injection, Inhalation (nebulized).
- Dosing units differ: Thymosin Beta-4 Fragment (TB4-Frag 17-23) is dosed in mcg–mg, Vasoactive Intestinal Peptide (VIP) in mcg — they operate at different scales.
- Frequency: Thymosin Beta-4 Fragment (TB4-Frag 17-23) is typically 2–3x weekly; Vasoactive Intestinal Peptide (VIP) is Daily intranasal or 1–2x weekly subcutaneous.
How each works
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.
Vasoactive Intestinal Peptide (VIP)
VIP activates VPAC1 and VPAC2 receptors coupled to cAMP, suppressing pro-inflammatory cytokines while promoting Th2 regulatory immune responses and Treg differentiation. In the CIRS/biotoxin illness framework pioneered by Shoemaker, VIP intranasal formulation demonstrates normalization of inflammatory markers and improvement in TGF-β, MSH, and VIP deficiency seen in CIRS patients. Pulmonary vasodilation effects have been studied for PAH.
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.