Acetyl Octapeptide‑1 is a synthetic bioactive octapeptide that has emerged as a topical alternative to neuromodulators such as botulinum toxin. The peptide sequence is an elongation of the N‑terminal portion of SNAP‑25 (Ac‑Glu‑Glu‑Met‑Gln‑Arg‑Arg‑Ala‑Asp‑NH₂), a protein required for formation of the SNARE complex, which mediates calcium‑dependent fusion of synaptic vesicles. By competing with SNAP‑25 for binding to the SNARE complex, this ingredient destabilizes vesicle fusion and reduces the release of catecholamines (e.g., adrenaline, noradrenaline) from presynaptic terminals. This decreased neurotransmitter release relaxes the facial muscles responsible for dynamic expression lines. Because it acts locally rather than systemically, it offers a non‑invasive, topical means to soften wrinkles and fine lines, particularly around the forehead and periocular region, without the paralysis associated with injectables.

Because acetyl octapeptide‑1 is water‑soluble and larger than many cosmetic actives, delivery strategies such as oil‑in‑water emulsions, dissolving microneedles or encapsulation are often used to improve skin penetration. In addition to neuromodulation, some reports indicate that the peptide may improve skin hydration and barrier function when combined with humectants, although robust data are limited. There is no substantive evidence of hair‑care applications; its primary utility remains in anti‑wrinkle facial care.