Pentapeptide-18 (Leuphasyl)

Pentapeptide-18 contains five amino acids and mimics the endogenous signaling peptide enkephalin. Lipotec markets it as Leuphasyl. It is used in expression-line skincare rather than as an approved drug, often alongside other neuro-inspired ingredients.

The proposed laboratory mechanism begins with enkephalin-receptor binding at a nerve ending. Reduced calcium inflow then limits release of acetylcholine, the contraction signal, potentially reducing small-muscle activation associated with expression lines.

It is marketed alongside Argireline, which acts at another step in neurotransmitter release. These mechanisms do not mean a topical cosmetic reaches or paralyzes muscle as an injection does. Finished-product goals should be described as smoother-looking or softer expression lines.

Serums and creams target forehead lines, crow’s-feet and other movement-related lines. Acetyl hexapeptide-8/Argireline and other actives are frequent combination partners.

Cosmetic ingredients do not require FDA preapproval. Appearance claims differ from claims to relax muscles or change body function, which would make the product a drug. Cosmetic use is not a therapeutic authorization.

Peptide-specific research is mainly computational or laboratory work, including modeling of target interactions. Human studies have used combination preparations, such as retinol-loaded formulations; their results cannot be assigned to pentapeptide-18 alone. No independent human efficacy trial of the isolated ingredient is described.

Topical use is generally reported as well tolerated and low-irritation at cosmetic levels, without an established systemic nerve/muscle effect. Independent safety data are limited, so patch testing is sensible for sensitive skin.