Tetrapeptide-21
/ Synthetic tetrapeptide; INCI 'Tetrapeptide-21'; photoaging-focused cosmetic peptideALIAS · Biopeptide-21 · Tetrapeptide-21 (INCI)
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Tier 4. Tetrapeptide-21 is a synthetic four-residue cosmetic peptide marketed under the trade name Biopeptide-21 (Sederma) for photoaging-focused applications, principally extracellular-matrix stimulation in dermal fibroblast cultures. The mechanistic basis derives from supplier in-vitro work on collagen and hyaluronic acid synthesis. Independent randomised topical-efficacy trials versus placebo are sparse in the indexed primary literature.
Supplier-published work positions Tetrapeptide-21 as a stimulator of dermal fibroblast extracellular-matrix synthesis — increased expression of type I collagen, hyaluronic acid, and laminin-5 in cell-based assays — with proposed downstream cosmetic effects on dermal density and photoaging endpoints. The specific receptor or signalling pathway driving the in-vitro signal has not been definitively characterised in independent primary literature.
Tier 4. Mechanism of action data are predominantly in-vitro and supplier-sponsored. Topical-efficacy work in human cosmetic application has principally been conducted by the supplier or contracted laboratories rather than in independent randomised trials.
No formal independent safety database beyond supplier patch-test and cosmetic-tolerability work. Systemic exposure from topical application is presumed low.
Regulatory status
- FDA status:
- Not FDA-approved
As with most INCI-numbered cosmetic peptides, the asymmetry between supplier in-vitro mechanistic claims and independent topical-efficacy data is the central evidentiary issue. Vendor product specifications (peptide sequence, purity, vehicle) are not always disclosed at point of sale.