Argireline
Cosmetic peptide
Also known as: Acetyl Hexapeptide-8, Acetyl Hexapeptide-3, Ac-EEMQRR-NH2
Evidence is limited to animal or in-vitro work. No human pharmacokinetics. Any human dose in circulation is extrapolated, and extrapolation across species routinely fails.
No systemic pharmacokinetic or half-life data exist. The 2025 CIR safety assessment reports a log P of -6.3 (percutaneous absorption unlikely) and the Panel concluded there is minimal skin penetration, implying low systemic exposure. In-vitro penetration figures vary widely by vehicle (0.22% through stratum corneum in one study, up to 30% across a synthetic membrane in another), these are penetration fractions, not pharmacokinetic parameters, and must not be read as one.
Not dosed per administration, used as a percentage in formulation, so the mcg model does not apply. Per the industry concentration-of-use survey reported in the CIR assessment: leave-on maximum 0.005% (eye lotions, face and neck), rinse-off up to 0.000005%. The CIR Panel concluded it is safe up to 0.005% and that data are INSUFFICIENT to support safety above that. Note the sharp conflict with commerce: peer-reviewed efficacy studies and marketed products commonly use 10% w/w, a concentration the Panel explicitly does not support, and where it notes a drug-like effect may become apparent at an unknown threshold.
Documented in the CIR assessment: a human repeated insult patch test in 50 subjects using a 0.05% mixture caused no sensitisation; a rabbit skin irritation study at the same concentration showed no erythema or oedema. In a double-blind placebo-controlled trial, 12 blepharospasm patients applied a 0.005% emulsion twice daily for ~7 months with no severe adverse events; 4 subjects (2 active, 2 placebo) had minor self-limiting eyelid irritation. By contrast a 10% w/w cream was reported to cause warmth, dryness, stinging, redness, desquamation, itching, or ocular irritation. Key gap: the Panel noted absence of systemic toxicity and genotoxicity data, mitigated only by minimal penetration, a rationale that does NOT extend to the 10% concentrations widely sold. Topical only; no established injectable or systemic use.