Instrumental Assessment of a Chemical Skin Biostimulator Combining Ammonium Trichloroacetate and Homocysteic Acid in Photoaged Mature Skin: A Single-Arm Prospective Study.

Mature photoaged skin is characterised by concurrent deterioration of dermal extracellular matrix, impairment of the epidermal barrier and dysregulated melanogenesis. Chemical skin biostimulators that remodel the dermis without inducing overt exfoliation may offer a multimodal alternative to conventional peels. In this single-arm, prospective study, 25 women with Fitzpatrick phototype II and clinical signs of facial photoageing received four sessions of a homocysteic acid (HoA)-containing chemical biostimulator incorporating ammonium trichloroacetate (ATCA), and phytic and citric acids accompanied throughout by a standardised home-care regimen. Instrumental endpoints included viscoelasticity assessed by Cutometer, three-dimensional wrinkle volume and texture quantified by Antera 3D, grey-level co-occurrence matrix (GLCM) metrics for hyperpigmentation, and sebum and hydration measurements; tolerability was assessed by clinical inspection at each visit, although safety was not a pre-specified endpoint. All three Cutometer elasticity parameters increased by approximately 24% and remained significantly improved at 12 weeks, with a continued rise in biological elasticity (R7), a temporal pattern compatible with progressive dermal remodelling, although no histological verification was undertaken. Antera 3D documented a rapid (50-62%) reduction in wrinkle volume and texture roughness at 2 weeks, followed by a partial regression stabilising at 79-83% of maximal improvement at 12 weeks. In the hyperpigmented subgroup (