Leuphasyl
A synthetic enkephalin-mimic pentapeptide marketed as a topical anti-wrinkle cosmetic active that theoretically relaxes facial expression lines.
Leuphasyl is a synthetic pentapeptide (Tyr-D-Ala-Gly-Phe-Leu-OH) designed as an enkephalin receptor mimic for topical cosmetic use, positioned as an anti-wrinkle ingredient on the theory that modulating enkephalin receptor activity at facial neuromuscular junctions attenuates dynamic muscle contraction. Its proposed mechanism is conceptually analogous to botulinum toxin but operates at far lower potency through a distinct receptor pathway. No clinical trials, controlled in vivo studies, or human safety data for leuphasyl exist in indexed literature; it appears almost exclusively in cosmetic ingredient databases, with its evidence base limited to a single integrative in silico and in vitro study.
Class
Synthetic pentapeptide (enkephalin analog)
Half-life
N/A (topical application)
Routes
Topical
Category
Skin, Hair & Cosmetic
Researched benefits
What it's studied for
Expression line reduction
Marketed to soften the appearance of dynamic expression lines by theoretically reducing repetitive facial muscle micro-contractions. This claim rests on the peptide's proposed enkephalin-mimicking mechanism rather than on published human efficacy data.
Facial muscle relaxation
Proposed to attenuate acetylcholine release or signal transmission at the dermal-epidermal neuromuscular interface, conceptually analogous to botulinum toxin but at much lower potency through a distinct receptor pathway.
Enkephalin pathway modulation
Designed to compete with endogenous enkephalin for opioid and related receptor sites at neuromuscular junctions, drawing on the established pharmacology of enkephalins. This is the primary studied research area for the peptide.
Potential anti-aging / anti-collagenase activity
A single integrative in silico and in vitro study found leuphasyl showed relatively strong binding to MMP-13, an enzyme involved in collagen breakdown, suggesting a possible noninvasive dermocosmetic role. This is computational and cell-based evidence only.
Mechanism
How it works
Leuphasyl is a synthetic pentapeptide built as a mimic of enkephalin, an endogenous opioid signaling peptide. The theoretical premise is that by competing with enkephalin for opioid and related receptor sites at facial neuromuscular junctions, the peptide modulates the neural signaling that drives repetitive muscle micro-contractions responsible for dynamic expression lines.
The proposed downstream effect is attenuation of acetylcholine release or signal transmission at the dermal-epidermal neuromuscular interface, reducing the strength of muscle contraction. This is conceptually analogous to the mechanism of botulinum toxin, but leuphasyl is claimed to operate at significantly lower potency and through a distinct receptor pathway rather than by cleaving SNARE proteins.
Beyond neuromuscular modulation, a single integrative study combining computational docking and laboratory testing reported that leuphasyl binds MMP-13, a matrix metalloproteinase implicated in collagen degradation. Inhibiting collagen breakdown is a plausible secondary route by which a topical peptide could support skin anti-aging, though this remains a preclinical signal rather than a demonstrated clinical effect.
It is important to note that this entire mechanistic framework is theoretical and preclinical. No clinical trials, controlled in vivo studies, human safety data, or animal efficacy studies for leuphasyl as a distinct compound are indexed in PubMed, and any efficacy claims are unsupported by independently published clinical evidence.
Dosing protocols
Dosing & administration
Dosing reflects protocols reported in research and community literature for educational purposes. It is not medical advice or a recommendation. Most peptides here are not approved for human use.
Cosmetic formulation
- Dose
- Not established
- Frequency
- Not established
- Timing
- Not established
- Duration
- Not established
- Route
- Topical
Leuphasyl is a topical cosmetic ingredient formulated into finished skincare products rather than dosed as an injectable peptide. No standardized use-concentration, injection dose, or regimen is documented in the available source.
- Leuphasyl is intended for topical cosmetic application only, not injection or systemic use.
- No standardized dosing, use-concentration, or reconstitution protocol is documented in the available literature.
- Because there are no controlled human studies, any concentration or application frequency reflects manufacturer or formulator choice, not evidence-based guidance.
Evidence
Research & clinical studies (1)
Integrative In Silico and In Vitro Evaluation of Vialox and Leuphasyl Pentapeptides for Antiaging Applications
Leuphasyl and Vialox pentapeptides showed distinct antiaging mechanisms, with leuphasyl binding more strongly to MMP-13 (a collagen-degrading enzyme) and both peptides exhibiting favorable safety and no cytotoxicity in skin cells, supporting potential as noninvasive dermocosmetic candidates.
PMID 42116636Combinations
Stacking & blends
Cosmetic anti-wrinkle blend
Broader softening of dynamic expression lines in topical formulations
Leuphasyl and Argireline (Acetyl Hexapeptide) are both marketed as neuromodulating cosmetic peptides that theoretically reduce facial muscle contraction through complementary pathways, and are frequently formulated together in anti-aging skincare. This is a common cosmetic pairing rather than a clinically validated combination.
Safety
Side effects & considerations
Contraindications & cautions
- None established for topical use
Leuphasyl is generally considered lower risk in research contexts, and no contraindications are established for topical use. Human safety data are absent; the single available study reported no cytotoxic effects on skin cells in vitro. Individual response varies.
FAQ
Leuphasyl — common questions
What is Leuphasyl?
Leuphasyl is a synthetic pentapeptide (Tyr-D-Ala-Gly-Phe-Leu-OH), also known by the cosmetic name Pentapeptide-18, designed as an enkephalin receptor mimic for topical cosmetic use. It is marketed as an anti-wrinkle active on the theory that modulating enkephalin receptor activity at facial neuromuscular junctions can attenuate dynamic muscle contraction and soften expression lines.
What is Leuphasyl primarily studied for?
Its primary research areas are expression line reduction, facial muscle relaxation, and enkephalin pathway modulation.
How does Leuphasyl work?
It is proposed to compete with endogenous enkephalin for opioid and related receptor sites at neuromuscular junctions, reducing acetylcholine signaling and repetitive muscle micro-contractions. This is conceptually similar to botulinum toxin but at much lower potency and through a distinct pathway. A single study also found it binds MMP-13, an enzyme involved in collagen breakdown.
Is Leuphasyl proven to reduce wrinkles?
No. There are no clinical trials, controlled in vivo studies, or human efficacy data for leuphasyl as a distinct compound. Its evidence base is limited to one integrative in silico and in vitro study, so any anti-wrinkle claims are theoretical and unsupported by independently published clinical data.
What are the side effects of Leuphasyl?
No contraindications are established for topical use, and the peptide is considered lower risk in research contexts. The single available study reported no cytotoxicity on skin cells. Human safety data, however, are absent, so individual response may vary.
Is Leuphasyl FDA approved?
No. Leuphasyl has no FDA approval and no drug regulatory status. It is sold as a cosmetic ingredient (Pentapeptide-18), is not regulated as a drug, and has no NDA or IND on file.
How is Leuphasyl used?
It is a topical cosmetic ingredient formulated into finished skincare products. It is not an injectable peptide, and no standardized dose or reconstitution protocol is documented.
