Acetyl hexapeptide-8 (or -3), better known by its brand name, Argireline (Lubrizol; Wickliffe, Ohio), is a synthetic peptide gaining popularity in cosmeceutical products for its antiaging benefits. Argireline was developed by the company Lipotec in 2001. Media, beauty bloggers, and product claims have likened this product to a “Botox [or other neurotoxin] alternative,” or “Botox mimicker.”
Mechanism of action
Understanding how Argireline works requires a brief refresher on the mechanism of action of botulinum neurotoxin (BoNT). BoNT relaxes facial muscles and smooths expression lines by inhibiting acetylcholine release at the neuromuscular junction.1 More specifically, the various serotypes of BoNT are single-chain polypeptides that target members of the SNARE complex: SNAP-25, syntaxin, and Vamp. The proteins within the SNARE complex are involved in the docking and fusion of presynaptic vesicles to the presynaptic membrane, necessary steps for acetylcholine release into the neuromuscular junction and muscle contraction. By blocking the action of the SNARE complex proteins, BoNT inhibits release of acetylcholine in the neuromuscular junction and prevents muscle contraction.
Dr. Chloe Goldman
Argireline is a synthetic peptide with the sequence Ac-EEMQRR-NH2.2 It is patterned after the N-terminal domain of SNAP-25, one of the members of the SNARE complex targeted by BoNT, and functions to interfere with the assembly of the SNARE complex. In this manner, Argireline would theoretically inhibit fusion of presynaptic vesicles and release of acetylcholine into the neuromuscular junction, thus impeding muscle movement. For this reason, it has been likened to topical Botox. Unlike Botox and other neurotoxins, Argireline was developed for topical application rather than injection.
Preclinical studies
In vitro work done 20 years ago demonstrated that Argireline can prevent assembly of the SNARE complex and inhibit neurotransmitter release with a potency similar to that of BoNT A (Botox).2
In 2013, Wang et al. evaluated the histologic effects of Argireline in aged mouse skin induced by D-galactose. For 6 weeks, Argireline was applied twice daily, and histological changes were assessed using hematoxylin and eosin (H&E) and picrosirius–polarization (PSP) stains. The researchers found elevated levels of type I collagen (P < .01) and reduced type III collagen (P < .05) with the Argireline treatment. These results demonstrated that Argireline could histologically enhance collagen in a manner consistent with skin rejuvenation.3
Clinical studies
In 2002, Blanes et al. assessed the antiwrinkle activity of Argireline by measuring skin topography from silicone implants in the lateral periorbital region of an oil/water (O/W) emulsion containing 10% of the acetyl-hexapeptide in 10 healthy women volunteers. The hexapeptide emulsion was applied twice daily in one lateral periorbital area, and the emulsion vehicle alone was applied twice daily on the contralateral side. Over 30 days of treatment, wrinkle depth was found to have decreased by 30%. The investigators also found that Argireline significantly hindered neurotransmitter release in vitro as robustly as BoNT A, though with notably lower efficacy. No toxicity or irritation was associated with this treatment.2 However, it should be noted that this small study conducted 2 decades ago evaluated only silicone implants with confocal microscopy to evaluate wrinkle depth. There was no subjective clinical assessment of dynamic facial wrinkles. As such, their study is an insufficient basis for drawing conclusions that Argireline is a BoNT mimic. Botox and other types of BoNT affect dynamic facial wrinkles mostly (i.e., wrinkles created by moving muscles of facial expression). This study primarily considers static wrinkles on periorbital skin. While static wrinkles may result from longstanding dynamic wrinkles, BoNT mainly targets dynamic wrinkles, again not comparing apples to apples.