Vialox (Pentapeptide-3V) Peptide

Vialox (Pentapeptide-3V) acts as a competitive post-synaptic acetylcholine receptor antagonist, similar to tubocurarine but with dermal-safe peptide structure. It prevents sodium influx into muscle cells, reducing contraction frequency without causing paralysis.

Vialox (Pentapeptide-3V, INCI: Pentapeptide-3) is a synthetic pentapeptide designed as a competitive antagonist of the nicotinic acetylcholine receptor (nAChR) at the neuromuscular junction. Its proposed mechanism mimics, in a topical and reversible fashion, the curare-like blockade exerted by tubocurarine, the prototypical plant alkaloid that competitively binds the post-synaptic α-subunit of the muscle-type nAChR. By occupying the acetylcholine (ACh) binding site without triggering channel opening, Pentapeptide-3 is hypothesised to reduce ion flux across the post-synaptic membrane, decreasing muscle fibre depolarisation in cutaneous mimetic muscles.

Post-Synaptic Acetylcholine Receptor Antagonism

At the neuromuscular junction, ACh released from motor neuron terminals normally binds the α1 subunits of the pentameric (α1)2β1δε nAChR, opening a cation channel that initiates an end-plate potential and subsequent muscle contraction. Pentapeptide-3V is reported to bind competitively at or near this ACh recognition site, blocking agonist access. Because the inhibition is competitive and reversible, the effect is concentration-dependent and decays as the peptide diffuses or degrades — a property considered desirable in topical cosmetic research where graded, reversible modulation is preferred over irreversible blockade.

Comparison to Botulinum and Argireline Pathways

Vialox is mechanistically distinct from botulinum toxin (BoNT/A), which cleaves SNAP-25 pre-synaptically to prevent ACh vesicle fusion, and from Acetyl Hexapeptide-8 (Argireline), which is proposed to mimic the N-terminal of SNAP-25 and competitively destabilise the SNARE complex. Vialox acts post-synaptically on the receptor itself, whereas Argireline and BoNT/A act pre-synaptically on the release machinery. This complementary mechanism is the rationale for formulations that combine the two peptides — they target different nodes of the same signalling cascade and are hypothesised to provide additive expression-line attenuation.

Downstream Effects on Mimetic Musculature

By dampening post-synaptic ACh signalling at superficial facial mimetic fibres, Pentapeptide-3V is hypothesised to reduce the amplitude of repeated micro-contractions that contribute to dynamic expression lines (glabellar, periorbital, forehead). Manufacturer in-vitro and ex-vivo data suggest a reduction in muscle cell contractility within 30 minutes of exposure, with reversal upon washout. However, peer-reviewed independent studies remain limited, and percutaneous penetration of a 5-amino-acid hydrophilic peptide to the level of the neuromuscular junction is a subject of ongoing research interest.

Formulation Considerations Affecting Mechanism

The functional output of Pentapeptide-3V in a finished formulation is strongly influenced by vehicle composition. Penetration enhancers, liposomal encapsulation, and pH (optimally 5.0–6.5 for peptide stability) all affect how much intact peptide reaches the stratum corneum-dermis interface. Research-grade material is typically supplied as the trifluoroacetate (TFA) salt of the free peptide and is studied at use concentrations of 2–5% of a stock solution in cosmetic emulsions.

Vialox is supplied for research as a solution containing the active peptide Pentapeptide-3V together with a stabilising vehicle. Because the commercial trade-name product is a multi-ingredient research preparation rather than a single pure compound, individual component data are listed below. The defining active is the synthetic pentapeptide; supplier formulations may additionally contain a humectant (typically butylene glycol or glycerin) and a preservative system.

Active Peptide Characterisation

Note on identifiers: Because Vialox is a trade-name formulation, no single canonical CAS number or molecular formula uniquely describes the product as supplied. Researchers requiring a single-molecule reference should specify the free pentapeptide (Pentapeptide-3, sequence GPRPA) and treat any CAS number provided on a supplier label as referring to the formulated material.

Vialox (Pentapeptide-3V) is typically supplied either as a lyophilized powder of the free pentapeptide (Gly-Pro-Arg-Pro-Ala) or as a pre-formulated aqueous cosmetic solution containing the active peptide together with stabilising excipients (glycerin, butylene glycol, phenoxyethanol). Handling requirements vary slightly between the two formats.

Reconstitution Protocol (Lyophilized Powder)

1. Equilibrate to room temperature. Remove the sealed vial from -20°C storage and allow it to reach ambient temperature (15-25°C) for 20-30 minutes before opening to prevent atmospheric moisture condensing onto the lyophilizate.
2. Select diluent. Sterile bacteriostatic water (0.9% benzyl alcohol) or sterile water for injection is appropriate for research-scale reconstitution. For topical formulation studies, a 1:1 water/propylene glycol vehicle is commonly used to improve stratum corneum partitioning.
3. Calculate target concentration. A typical working stock is 5 mg/mL (e.g., 10 mg peptide + 2 mL diluent). Final cosmetic formulations referenced in the supplier literature use 2-5% w/w of the diluted Vialox solution, corresponding to approximately 100-250 ppm of free peptide.
4. Inject diluent slowly down the inner wall of the vial — do not direct the stream onto the cake.
5. Swirl gently for 30-60 seconds until fully dissolved. Do NOT vortex or shake vigorously; mechanical shear can fragment the peptide and aerosolise material.
6. Visual inspection. The reconstituted solution should be clear and colorless. Any cloudiness, particulates, or yellow tint indicates degradation or contamination — discard.

Compound-Specific Handling Notes

• Arginine residue: The single Arg in the sequence makes Vialox mildly cationic and prone to electrostatic interactions with anionic surfactants (SLS, SLES). Avoid co-formulating with strongly anionic systems during stability testing.
• Proline-rich backbone: The two proline residues confer relative resistance to general proteolytic degradation but the peptide remains susceptible to extreme pH. Maintain formulations between pH 5.0 and 7.0.
• Avoid metal contact: Use polypropylene or borosilicate glass for storage. Trace metals (Cu²⁺, Fe³⁺) can catalyse oxidation of formulation excipients adjacent to the peptide.
• Personal protective equipment: Standard laboratory PPE (gloves, lab coat, eye protection) is sufficient. Vialox is not classified as a hazardous substance for research handling.

Working Stock Aliquoting

To minimize freeze-thaw cycles, divide the reconstituted stock into single-use aliquots (typically 100-250 µL) in low-binding microcentrifuge tubes and store at -20°C. Each aliquot should be thawed only once for experimental use.

Proper storage is essential to preserve the integrity of the Pentapeptide-3V sequence (Gly-Pro-Arg-Pro-Ala) and ensure reproducible research outcomes across topical formulation and in vitro receptor studies.

Lyophilized Powder

• Long-term storage: -20°C or colder, in the original sealed vial with desiccant. Stability under these conditions is typically 24-36 months from date of manufacture.
• Short-term storage: 2-8°C is acceptable for up to 30 days if the vial is to be used soon. Keep desiccated and protected from light.
• Transit conditions: Brief exposure to room temperature (up to 25°C) during shipping for 5-7 days does not measurably degrade the lyophilized peptide, owing to the absence of solvent water.

Reconstituted Solution

• 2-8°C (refrigerated): Aqueous reconstituted Vialox is stable for approximately 2-4 weeks when stored in a sealed, sterile container away from light. Bacteriostatic water-based stocks may retain activity longer than plain water stocks due to benzyl alcohol preservation.
• -20°C (frozen aliquots): Stable for 6-12 months. Freeze-thaw cycles should be limited to no more than 3; each cycle increases the risk of aggregation and minor cleavage at the Gly-Pro bond.
• Room temperature: Not recommended for reconstituted material beyond the workday; bacterial contamination and hydrolytic degradation become rate-limiting within 24-48 hours.

Compound-Specific Stability Notes

• pH sensitivity: Optimum stability is observed between pH 5.0 and 7.0. Below pH 4 or above pH 8, hydrolysis of the peptide bonds (particularly adjacent to proline) accelerates measurably.
• No disulfide bonds: Vialox contains no cysteine residues, so it is not susceptible to oxidative dimerisation — a stability advantage over peptides like GHK-Cu or Thymosin Alpha-1.
• No methionine or tryptophan: The peptide lacks easily oxidised residues, making it relatively robust to atmospheric oxygen, though formulations should still be protected from prolonged light exposure.
• Arginine hygroscopicity: The Arg residue gives the lyophilized powder mild hygroscopic character; vials should be opened only briefly and resealed promptly with desiccant.

For finished cosmetic prototypes incorporating Vialox, stability testing under ICH Q1A guidelines (25°C/60% RH and 40°C/75% RH) is recommended to characterise shelf life in the intended vehicle.