Pentapeptide-3 vs Acetyl Hexapeptide-8: Vialox and Argireline Compared for Expression-Line Serums

Pentapeptide-3 and Acetyl Hexapeptide-8 are both water-soluble peptides used for the look of expression lines, but they are pitched at opposite sides of the nerve-to-muscle junction: Acetyl Hexapeptide-8, sold as Argireline, is described as loosening acetylcholine release inside the nerve ending, while Pentapeptide-3, sold as Vialox, is described as blocking the receptor on the muscle side. Acetyl Hexapeptide-8 has the much larger published record, so it is the safer single choice, and Pentapeptide-3 makes most sense as a second peptide with a different target. At typical supplier levels both end up in the same range of roughly 10 to 50 ppm of peptide in a finished serum.

The pages that rank for this comparison are mostly evidence summaries or blend listings. This one is written for the bench: what each molecule is, what the numbers behind each one really are, how much peptide your formula carries at a given dose of solution, and how to put both in one bottle.

Two Different Molecules, Two Different Names

Pentapeptide-3, the Vialox peptide

Pentapeptide-3 is the five-amino-acid sequence Gly-Pro-Arg-Pro-Ala with an amidated end, CAS 135679-88-8 and a molecular weight of about 495.6 Da. It carries no acetyl or fatty acid group, which makes it very hydrophilic. Vialox is the trade name it was launched under by Pentapharm, the Swiss company DSM acquired in 2007. Our Pentapeptide-3 Solution and the original branded Vialox (Pentapeptide-3) Solution share the INCI Aqua, Glycerin, Pentapeptide-3 and carry about 1000 ppm of peptide, which is 0.1 percent.

Watch the name. Palmitoyl Pentapeptide-3 was the old INCI name of the Matrixyl peptide Pal-KTTKS, which is now listed as Palmitoyl Pentapeptide-4 and is sold as Palmitoyl Pentapeptide-4 Powder. It is a collagen-signal peptide with an unrelated sequence, so a supplier sheet that mixes the two names deserves a second look.

Acetyl Hexapeptide-8, the Argireline peptide

Acetyl Hexapeptide-8 is Ac-Glu-Glu-Met-Gln-Arg-Arg-NH2, CAS 616204-22-9, a little under 890 Da. Lipotec, now part of Lubrizol, launched it as Argireline, and older documents list it as Acetyl Hexapeptide-3, the same molecule under its earlier INCI name. Its sequence copies the N-terminal end of SNAP-25, a protein nerve endings use to release acetylcholine. It is sold mostly as a 0.05 percent water solution, which is what our Acetyl Hexapeptide-8 Solution is, and as a neat Acetyl Hexapeptide-8 Powder.

Where Each Peptide Is Said to Act

A facial muscle contracts when a nerve ending releases acetylcholine and the muscle cell detects it through nicotinic receptors. Acetyl Hexapeptide-8 works on the first half of that relay. It competes with SNAP-25 for a place in the SNARE complex, the protein assembly that docks vesicles of acetylcholine onto the nerve membrane, so the complex forms less firmly and fewer vesicles empty. Nothing is cut or destroyed, which is why the effect is described as a softer contraction rather than a stopped one.

Pentapeptide-3 is described as working on the second half. The cosmetic patent filed in 2004 by Labo Cosprophar calls it curare-like and says it competes with acetylcholine for the receptor on the muscle membrane. If the receptor is occupied, the muscle cell responds less to the same signal. Marketing often links Vialox to snake venom, but that story belongs to its sister ingredient Syn-Ake, our Dipeptide Diaminobutyroyl Benzylamide Diacetate Powder, which was modeled on the viper peptide waglerin-1. The Pentapeptide-3 sequence was first patented in 1990 as a peptide that inhibits fibrin aggregation, long before it was used in skin care.

Because one peptide is aimed at the sending side and the other at the receiving side, they do not compete for the same target. That is the whole logic behind putting them together. It is a mechanistic argument, not a measured result, and the next section shows how unevenly the two are supported.

What the Evidence Behind Each Number Really Is

Acetyl Hexapeptide-8 has an independent record

The original paper by Blanes-Mira and colleagues in the International Journal of Cosmetic Science in 2002 reported up to 30 percent less wrinkle depth after 30 days with a 10 percent solution in an oil-in-water emulsion. A 2013 randomized, placebo-controlled study in the American Journal of Clinical Dermatology followed 60 Chinese subjects for four weeks and reported a total anti-wrinkle response of 48.9 percent for the peptide against 0 percent for placebo, by subjective assessment. A 2025 review in Pharmaceuticals on acetyl hexapeptide-8 gathers these trials together with permeation work, and it is candid that a hydrophilic peptide of this size crosses intact skin poorly. A 2015 in vitro study from a US FDA laboratory, published in Cutaneous and Ocular Toxicology, applied it at 10 percent and recovered only a small fraction in the epidermis and none in the dermis.

Pentapeptide-3 rests on supplier and patent data

For Pentapeptide-3 the figure quoted on most product pages is up to 49 percent smaller wrinkles and up to 47 percent less roughness after 28 days of a cream with 5 percent Vialox. That result comes from the manufacturer, and its design, panel size and placebo arm were never published. The 2004 patent adds a cell result: in a nerve-muscle co-culture at 0.3 percent, contraction frequency fell 69.75 percent after one minute and 60.75 percent after two hours. Reviews of cosmetic peptides, including a 2020 review in Frontiers in Chemistry, note that the efficacy data for this ingredient come from the manufacturer, and we found no independent placebo-controlled study. Note too that up to describes the best responder, not the panel average.

The fair reading is that Acetyl Hexapeptide-8 is the better documented ingredient by a wide margin, while Pentapeptide-3 offers a different, smaller molecule with a plausible but untested rationale. At about 496 Da it sits close to the 500 Da rule of thumb for passive skin penetration, while the hexapeptide is well above it. Size alone does not prove that either reaches the muscle, and no study has measured that for Pentapeptide-3.

Pentapeptide-3 vs Acetyl Hexapeptide-8 at the Bench

Use levels and the peptide you actually add

The two solutions are made at different strengths, so compare peptide, not liquid. Our Pentapeptide-3 cards give 1.0 to 3.0 percent of the supplied liquid in leave-on products. At about 1000 ppm of peptide, 1 percent of solution puts about 10 ppm of Pentapeptide-3 into the finished product and 3 percent puts about 30 ppm. Lipotec recommends 2 to 10 percent of its 0.05 percent Argireline solution, so 5 percent of solution delivers about 25 ppm of Acetyl Hexapeptide-8 and 10 percent delivers about 50 ppm. Despite the different liquid doses, a typical serum ends up with a similar order of peptide from either one. Our Acetyl Hexapeptide-8 grades ask you to confirm the active content on each lot's certificate of analysis, and the Acetyl Hexapeptide-8 Amplified Solution is the higher-strength option when you want more peptide in fewer grams.

Phase, temperature and pH

Both peptides go into the water phase at the end of the process. Add them below 40 C, after an emulsion has formed and cooled, and do not heat them or put them in the oil phase. The Pentapeptide-3 cards give a finished pH of 4.0 to 6.0. The Argireline sheet gives a working range of 3.0 to 8.0 and lists oxidants, electrophiles and tannins as incompatibilities. The window both documents accept is 4.0 to 6.0, so a serum finished around pH 5.0 to 5.5 suits the pair, and it also keeps you clear of strong acid exfoliant systems that neither peptide belongs in.

Compatibility in a mixed formula

Neither peptide needs an unusual base. Glycerin, a hyaluronic acid solution, mild thickeners and a broad-spectrum preservative are the usual neighbors. Keep peroxides, high doses of strongly oxidizing antioxidants and tannin-rich botanical extracts out of the peptide phase. If the brief also calls for GHK-Cu, which our Pentapeptide-3 card lists as a pairing idea, keep the formula free of strong chelators at levels that pull copper and check color during stability. Add each peptide solution separately with gentle stirring and record clarity and pH after each one, because a salt or thickener added afterward is the most common cause of haze.

Building One Serum With Both

A simple 100 g bench batch can start from water to balance, 3 to 5 percent glycerin, a hydrated gum or hyaluronic solution for slip, a preservative at its supplier's level, and in the cool-down 2 g of Pentapeptide-3 Solution and 5 g of Acetyl Hexapeptide-8 Solution. That gives roughly 20 ppm and 25 ppm of the two peptides. Adjust the pH to about 5.0 to 5.5 at the end and record it. No published study has tested this exact pair, so use the numbers as a starting frame for your own stability and preservative challenge testing, not as a proven combination.

If you want a third peptide, choose one with yet another route rather than doubling a target. Pentapeptide-18 acts before the signal starts by lowering how excitable the nerve is, and our Pentapeptide-18 vs Acetyl Hexapeptide-8 comparison covers the only supplier test in which two expression-line peptides were measured alone and together. Syn-Ake, by contrast, is claimed to act on the same muscle receptor as Pentapeptide-3, so stacking those two is more likely to be redundant than additive. Acetyl Octapeptide-3 overlaps with Acetyl Hexapeptide-8 in the same way, which our Acetyl Octapeptide-3 vs Acetyl Hexapeptide-8 guide explains.

Which One to Choose

If the formula can carry only one expression-line peptide, choose Acetyl Hexapeptide-8. It has independent trials, permeation data and the name more shoppers recognize on a label. Choose Pentapeptide-3 as the second peptide when you want a receiving-side mechanism next to it, a shorter and smaller molecule, or a story that does not depend on the most common ingredient in the category. Choose the branded Vialox solution only if your packaging or marketing names the trade name, because the IO Pentapeptide-3 Solution carries the same INCI at a lower price.

Keep claims cosmetic. Smoother-looking forehead lines, softer-looking crow's feet and a more relaxed-looking expression are appropriate. Comparing a serum to injections, saying it stops muscle movement or that it changes how nerves work moves the product out of cosmetics in the US, and the supplier figures above describe raw materials, not your finished product. Both peptides and their relatives are in our peptide solutions section, and dry grades are in our peptide powders section.

Sources

Blanes-Mira C. et al., International Journal of Cosmetic Science, 2002, on Acetyl Hexapeptide-8. Wang Y. et al., American Journal of Clinical Dermatology, 2013, randomized placebo-controlled study in 60 subjects. Kraeling M.E.K. et al., Cutaneous and Ocular Toxicology, 2015, in vitro skin penetration of acetyl hexapeptide-8. Acetyl Hexapeptide-8 in Cosmeceuticals, a review of skin permeability and efficacy, Pharmaceuticals, 2025. Errante F. et al., Frontiers in Chemistry, 2020, review of cosmetic peptides. Labo Cosprophar AG cosmetic patent on the Gly-Pro-Arg-Pro-Ala amide, filed 2004. Use levels, INCI and pH come from the IngredientOS product cards and the Lipotec Argireline technical sheet.

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