Overview
Vialox is pentapeptide-3, identified by PubChem as glycyl-L-prolyl-L-arginyl-L-prolyl-L-alaninamide (C21H37N9O5, MW 495.6, CAS 135679-88-8) — a five-residue C-terminally amidated peptide, GPRPA-NH2.
It belongs to the 'topical neuromuscular' category of cosmetic peptides, marketed as a curare-mimetic: the proposition is antagonism at the postsynaptic acetylcholine receptor of the neuromuscular junction, reducing muscle contraction and therefore the appearance of expression lines. This places it alongside acetyl hexapeptide-8 (Argireline) as a so-called 'botox-like' peptide.
The mechanism claim and the delivery reality should be assessed separately, and the published review literature on this class is direct about the gap. For a topical peptide to antagonise neuromuscular junction receptors, it must cross the stratum corneum, traverse the epidermis and dermis, and reach the junction at a pharmacologically active concentration. In the closely-studied comparator acetyl hexapeptide-8, reviewers concluded that hydrophilic character and molecular size limit permeability, that specialised emulsion strategies are used to try to improve delivery, and that
the ability to reach neuromuscular junctions remains uncertain — while clinical measures such as wrinkle depth and elasticity did show improvement, through mechanisms that remain incompletely understood.
The honest position for Vialox is the same: the appearance benefit reported for this class is not necessarily evidence that the advertised neuromuscular mechanism is what produces it.
The limiting factor for every topical peptide is delivery. Peptides are hydrophilic and relatively large, while the stratum corneum is a lipophilic barrier built to exclude exactly such molecules. A peptide that performs well in a fibroblast culture has not thereby been shown to reach fibroblasts through intact skin. Reviews of cosmeceutical peptides identify this permeability gap — not receptor pharmacology — as the principal open problem, and note that formulation strategies such as oil-in-water and water-in-oil-in-water emulsions are used to try to close it with uncertain success.
What the evidence shows
Separated by study type- HumanClinical trials and human studies
- Used in finished cosmetic products. Independent controlled clinical trials isolating this ingredient were not located. For the closest-studied comparator in this class, clinical studies indicate reduced wrinkle depth and improved elasticity and hydration, with mechanisms incompletely understood.
- AnimalRodent and other animal models
- Not the primary evidence base.
- In vitroCell and tissue studies
- Receptor antagonism is the design rationale rather than a demonstrated in-skin effect.
Key studies & findings
2 studies- 1
For the closely-related topical neuromuscular peptide acetyl hexapeptide-8, a review concluded that hydrophilic character and molecular size limit stratum corneum permeability and that the ability to reach neuromuscular junctions remains uncertain, even though clinical studies indicate reduced wrinkle depth and improved elasticity.
- 2
PubChem identifies pentapeptide-3 as glycyl-L-prolyl-L-arginyl-L-prolyl-L-alaninamide (C21H37N9O5, CAS 135679-88-8), with Vialox listed among its synonyms.
Benefits & effects
2 documentedReported reduction in expression line appearance for this peptide class
Conformationally constrained, amide-stabilised design
Side effects & safety
2 reportedSafety noteCosmetic ingredient used topically in finished formulations. Injecting cosmetic peptides is not an established route, has no supporting safety data, and is not a use these ingredients were characterised for.
Generally well tolerated as a cosmetic ingredient
Advertised neuromuscular mechanism is not demonstrated for topical delivery
Limitations & open questions
The advertised mechanism requires the peptide to reach the neuromuscular junction, which topical delivery has not been shown to achieve for this class. Reported appearance benefits may arise from hydration, barrier or film effects rather than from neuromuscular antagonism. No independent controlled trial isolating this specific ingredient was located.
Pharmacology
Pentapeptide-3 is C21H37N9O5, MW 495.6, CAS 135679-88-8, PubChem CID 11605666. The C-terminal amide reduces susceptibility to carboxypeptidase degradation. The two proline residues constrain conformation, which is typical of peptides designed to hold a defined receptor-binding shape.
Frequently asked questions
Is Vialox a topical Botox?
No. Botulinum toxin is injected and blocks acetylcholine release presynaptically. Vialox is a topical peptide proposed to block the postsynaptic receptor — a different mechanism, a different route, and a different order of effect. Whether it reaches the junction at all is not demonstrated.
Do peptides like this actually reduce wrinkles?
Clinical studies of the closest-studied peptide in this class do report reduced wrinkle depth and improved elasticity and hydration. What remains unclear is whether the advertised neuromuscular mechanism is responsible, since delivery to the neuromuscular junction has not been established.
What does the '-NH2' at the end of the sequence mean?
The C-terminus is amidated rather than a free acid. This is a common stability modification that makes the peptide resistant to carboxypeptidase degradation.
Citations
1 sources- 1