Myristoyl Hexapeptide-16 vs Myristoyl Pentapeptide-17 for Lash and Brow Serums

What the two peptides have in common

Both are myristoylated peptides. The fatty-acid modification can change affinity and formulation behavior compared with an unmodified, freely water-soluble peptide. Both appear in leave-on lash, brow and hair-conditioning concepts, but neither should be described as a drug or as treating a hair-loss disorder. Consumer language such as fuller-looking, conditioned or less breakage-prone lashes must be supported on the finished product.

The practical difference is the commercial grade

An INCI name is not a complete purchase specification. Request manufacturer and product code, peptide identity, assay or active-content basis, carrier solvents, solubilizers, preservatives, appearance, pH range, storage, shelf life and analytical method. A supplier may offer the peptide as a prepared solution rather than neat material. Comparing use percentages without normalizing active peptide content can produce a false cost and performance comparison.

Choose one peptide, a blend, or neither

Select a single grade when it has a relevant evidence package and simplifies the formula. A two-peptide blend may support a broader marketing story, but it adds carrier load and makes claim attribution harder. If the project cannot fund lash- or brow-specific testing, a restrained conditioning claim may be more defensible than building a crowded hero-active list.

Formulating the water-based serum

Start with the supplier's order of addition, temperature and pH guidance. Account for glycols, alcohol, salts and preservatives introduced by every stock solution. Use low-tack humectants and a rheology system that coats without stringing. Confirm that the peptide remains solubilized after electrolyte and polymer addition; immediate clarity does not prove storage stability.

Applicator and eye-area safety

Brushes, flocked tips and mascara-style wands create different doses and contamination patterns. Validate fill weight, wiper fit, dose repeatability, leakage, drying around the neck and repeated-use microbiological risk. Complete preservative efficacy, package compatibility and a qualified eye-area safety assessment. Avoid prostaglandin analogues or drug-like positioning in an ordinary cosmetic brief.

How to substantiate a fuller-looking claim

Define the endpoint before the study: visible density, length appearance, breakage, gloss or conditioning. Use standardized photography, fixed application instructions and a suitable duration. Record concomitant mascara, extensions and grooming. Supplier studies can guide study design, but results from one proprietary blend do not automatically transfer to a formula assembled from other grades.

B2B quotation checklist

State the exact peptide grade or request alternatives; target active basis; lash, brow or dual use; fragrance and alcohol policy; fill size; applicator; destination markets; claim wording; stability protocol; safety assessment; MOQ; sample quantity; lead time and change-notification requirements. Approve bulk only after the pilot formula and market pack have passed the agreed tests.

Frequently asked B2B question

Can supplier data support the finished-product claim?

Supplier documentation can support ingredient selection and claim rationale, but transferability depends on the exact grade, active dose, vehicle, population, endpoint and use conditions. Material claims should be reviewed separately from claims on the finished cosmetic.