Matrixyl is a cosmetic topical peptide — Palmitoyl Pentapeptide-4 (Pal-KTTKS), a matrikine (a collagen-fragment messenger peptide) trademarked by Sederma. It is not an injectable or systemic research peptide.
Class
Cosmetic topical peptide; Palmitoyl Pentapeptide-4 (Pal-KTTKS), a matrikine. Single compound.
Mechanism
The pentapeptide KTTKS, a fragment of procollagen, is conjugated to a palmitoyl fatty acid to improve skin penetration. As a matrikine it signals dermal fibroblasts to increase production of collagen, elastin, and other extracellular-matrix components — in effect a "sub-injury" repair signal applied to the skin.
Research summary
Important context: the evidence base is cosmetic and dermatological (topical), not systemic or injectable. Within that domain it is reasonably supported. Topical clinical trials — including double-blind, split-face randomized controlled trials reported in the International Journal of Cosmetic Science — show wrinkle-depth and skin-roughness reductions of roughly 15–37%, with tolerability better than retinol. None of this transfers to injectable or systemic use; Matrixyl's evidence base should not be equated with that of injected research peptides.
Human clinical trial data
In the 12-week, double-blind, placebo-controlled, split-face randomized clinical study by Robinson and colleagues (2005), 93 Caucasian female subjects aged 35-55 applied a moisturizer control product vs. the same moisturizer product containing 3 ppm pal-KTTKS (PubMed). There is no studied injectable or systemic protocol.
Clinical / safety context
Used as a cosmetic ingredient with a strong skin tolerability record; it is not a drug and no systemic exposure is intended. Safety beyond cosmetic skin application is uncharacterized.
Evidence quality — Moderate, but only for cosmetic skin-care use
There is reasonable cosmetic skin-care evidence and zero evidence for injection or systemic use.
Notes
Pal-KTTKS / palmitoyl pentapeptide-4 (historically labeled "-3"). This is a skincare ingredient; on a research-peptide platform it should be framed as topical-cosmetic, distinct from the injectable peptide catalogue.