Peptide Library, the sequences behind RUSKI lash care

We label evidence with four letters so you can see strength at a glance. S - Strong: published, peer-reviewed or finished-product data that directly supports the appearance claim being made. M - Moderate: solid manufacturer or finished-product panels, or well-designed studies with relevant limitations. E - Emerging: supplier dossiers, small panels, or plausible data from a related tissue (often scalp hair) that has not been confirmed in independent lash trials. T - Theoretical: mechanism or analogy only; useful for formulation rationale, not for a finished-product promise.

Most cosmetic lash peptides sit at E or M for lashes specifically, even when the chemistry is well characterised. That is not a reason to discard them - it is a reason to keep claims appearance-only and to keep the source type visible.

INCI: Copper Tripeptide-1 (GHK-Cu). Role: hero copper peptide on Peptide Lash Serum (RL-LGS-001) for a denser, longer-looking lash line. Disclosed in the live INCI ahead of MP-17, MH-16 and Biotinoyl Tripeptide-1.

Evidence: peer-reviewed skin-repair and hair-follicle signalling literature - E for lashes specifically (no large dedicated eyelash RCTs), thicker in skin/hair contexts. Appearance claim only: supports the look of denser, longer, better-conditioned lashes with consistent use. Finished-product panel on file for the serum.

INCI: Myristoyl Pentapeptide-17. Formulator trade name: SymPeptide XLash (not Widelash). Role: supporting length- and fullness-appearance peptide in the hero serum (behind GHK-Cu) and lead peptide across several peptide mascaras.

Evidence: largely manufacturer consumer-panel data on the look of longer, denser lashes - typically E to M for lashes, not S from large independent RCTs. Companion chemistry is often Myristoyl Hexapeptide-16. Appearance claim only: supports the look of longer, fuller, better-conditioned lashes with consistent use.

INCI: Myristoyl Hexapeptide-16. Role: usual companion lipopeptide to MP-17 in length-appearance conditioning stacks; supports fibre conditioning rather than standing alone as a hero claim.

Evidence: supplier and manufacturer data, typically studied alongside MP-17 rather than in standalone lash trials, E for lashes. Appearance claim only: conditions the fibre for a smoother, better-looking lash line when formulated with its companion peptide.

INCI: Biotinoyl Tripeptide-1. Formulator trade names: Croda Widelash; also a component of Procapil-class complexes. Role: biotinylated carrier peptide for conditioning at the lash line and in day-wear or prep formulas.

Evidence: mostly scalp-hair and manufacturer dossiers, E for lashes, sometimes M in hair contexts. Appearance claim only: conditions for the look of healthier, better-supported fibres; not a biotin-deficiency treatment and not a growth drug.

INCI: Acetyl Tetrapeptide-3 (Ac-KGHK). Often paired with red clover extract in Capixyl-class complexes. Role: density- and architecture-appearance peptide in Bioactive Density and related dual-use formulas, not an MP-17 length lead.

Evidence: manufacturer Capixyl dossiers and scalp-hair clinical work, M in hair contexts, E when extrapolated to lashes. Appearance claim only: supports the look of a denser, better-anchored lash or brow line; not AGA or DHT drug action.

These peptides are not medicines and do not equal prostaglandin analogues or Latisse. We sell visibly longer, denser-looking results from consistent cosmetic use - not a growth-drug claim. Fragrance and other formula choices are separate and disclosed per product.

For how we grade finished-product panels versus supplier dossiers, read Clinical Evidence. For why we leave prostaglandin analogues out, read the prostaglandin-free explainer. For a narrative walkthrough of peptide science, start with Peptides for lashes.