Palmitoyl Pentapeptide-4, Pal-KTTKS
Evidence Grade D — Primarily preclinical. 11 published studies, mostly animal models. 0 registered clinical trials.
Matrixyl is a cosmetic peptide ingredient widely used in anti-ageing skincare products to stimulate collagen production. It mimics a natural collagen fragment that signals skin cells to make new collagen. Among cosmetic peptides, it has one of the stronger evidence bases — the largest randomised controlled cosmetic peptide trial (93 subjects) showed significant wrinkle improvement. It has no pharmaceutical approval.
11 published studies: 7 human, 1 animal, 4 in-vitro, 0 reviews
Matrixyl has no pharmaceutical authorisation. It is one of the better-studied cosmetic peptides, with the largest randomised controlled cosmetic peptide trial to date (93 subjects, double-blind, 12 weeks) demonstrating significant wrinkle improvement versus vehicle.
Among cosmetic peptides, Matrixyl has a relatively robust evidence base for topical skin appearance improvement. However, these are cosmetic efficacy studies, not pharmaceutical trials, and the standards of evidence differ significantly. Matrixyl is a topical cosmetic ingredient — this context should be distinguished from injectable peptide use.
Research suggests Matrixyl acts as a 'matrikine' — a peptide fragment from collagen breakdown that signals fibroblasts to produce new collagen. The palmitoyl (fatty acid) group enhances skin penetration and cell membrane interaction. In vitro studies report increased production of collagen types I, III, and IV, as well as fibronectin and hyaluronic acid. These laboratory observations have been partially supported by controlled cosmetic trials.
Research suggests the Robinson 2005 study (93 subjects, double-blind, 12 weeks) provides meaningful evidence of cosmetic efficacy — the best-designed trial for any cosmetic peptide. Laboratory studies show increased production of multiple collagen types and other skin structural proteins. However, the trial was conducted by the company that markets the ingredient, and independent replication is limited. As with all cosmetic peptide claims, these are skin appearance improvements from topical formulated products — a very different context from injectable use.
No trials registered on ClinicalTrials.gov for this compound.
The information on this page is provided for educational and research reference purposes only. This is not medical advice. Always consult a qualified healthcare professional before making any health-related decisions.
GHK-Cu has no pharmaceutical authorisation from any regulatory agency. It is widely available as a cosmetic ingredient in over-the-counter skincare products, where it is marketed for skin conditioning. A small study comparing GHK-Cu cream to vitamin C and retinoic acid creams reported improvements in skin appearance measures. No pharmaceutical clinical trials for injectable GHK-Cu have been completed. The compound's cosmetic use (topical, in formulated skincare products) should be clearly distinguished from its unregulated availability as an injectable research compound. These represent fundamentally different risk profiles.
Epitalon has no marketing authorisation from any major regulatory agency. No controlled human clinical trials have been conducted. Animal lifespan studies in mice reported by the Khavinson group form the core evidence base. The telomerase activation claims are based on in vitro studies and mouse models from a single research programme. Independent replication of the key findings has not been published. The relationship between in vitro telomerase activation and any clinical outcome in humans is not established. Products available through unregulated channels lack pharmaceutical quality assurance.
FOXO4-DRI has no marketing authorisation. No human clinical trials have been conducted. The evidence comes from a single high-profile publication (Cell, 2017) demonstrating effects in three mouse models. The senolytic field is an active area of pharmaceutical research, but FOXO4-DRI faces significant challenges for clinical translation, including its large size (46 amino acids), manufacturing complexity, and the absence of human pharmacokinetic or safety data. Products available through unregulated channels — which would need to reliably synthesise a 46-amino-acid all-D-amino-acid peptide — face exceptional quality assurance challenges.
