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Leuphasyl

Tier 3 · Reported use
Also known as Pentapeptide-18 · Leuphasyl peptide

The strongest evidence present is Tier 1 human observational work: the Dragomirescu et al. (2014) study published in Cosmetics/MDPI reporting topical application at the mimic-muscle level and wrinkle regression measured with the pro-derm Analyser (src-1, src-11), plus manufacturer-sponsored split-face studies (src-4). However, several sources explicitly note that the clinical evidence base is thin and primarily manufacturer-sponsored, with no independent peer-reviewed clinical trials reported as of 2026. Much of the mechanistic and additional-effect literature (EGFR/PI3K binding, MMP targeting, anti-melanogenic activity, ADMET) is in silico, in vitro, or theoretical only.

Half-life
Not recorded
Routes
Topical
Goals
Anti-aging / cosmetic skin health · Wrinkle reduction · Skin brightening (analog, in vitro)
Cost / mg
Not recorded

How it works

According to the sources, Leuphasyl (Pentapeptide-18) is a synthetic five-amino-acid peptide modeled on the body's own enkephalin opioid peptides. Reviews and vendor materials describe it as working like a topical, botox-like relaxant: it is reported to bind enkephalin/opioid receptors on the nerve side of the neuromuscular junction and dampen the release of acetylcholine, the signal that makes facial muscles contract. With less contraction of the muscles that create expression lines (such as around the eyebrows and eyes), sources report a reduction in the depth of expression wrinkles. Unlike botulinum toxin, several profiles note it acts at the receptor level upstream and is said to preserve partial muscle movement rather than freezing it. Sources describe it as applied topically in creams, gels, or serums, often combined with Argireline for a stronger effect.

Overview

Overview

Leuphasyl (also called Pentapeptide-18 or Pentapeptide-3, INCI usage varies between sources) is a synthetic pentapeptide marketed as a cosmeceutical anti-wrinkle ingredient. A tier-4 profile states it was developed by Lipotec S.A. (now Lubrizol) in Barcelona in the mid-2000s as an enkephalin analog (src-3, src-14, src-39). Its reported sequence is H-Tyr-D-Ala-Gly-Phe-Leu-OH; a vendor page lists molecular formula C29H39N5O7, molecular weight ~569.65 g/mol, and CAS 64963-01-5 (src-13), and an ingredient guide adds FDA UNII PO4D55T1IG (src-43).

What the sources describe

A tier-1 MDPI review describes Leuphasyl as a botox-like pentapeptide used in cosmetic science that inhibits neuromuscular synapses in mimic muscles by acting like enkephalins, linking the enkephalin receptor to nerve cells to modulate acetylcholine release in the synaptic space, resulting in muscle relaxation and reduction of expression wrinkles (src-1, src-2, src-3). Sources describe it as based on the natural enkephalin opioid pentapeptides leucine-enkephalin and methionine-enkephalin, first identified by Hughes et al. in 1975, with a D-alanine substitution at position 2 said to increase resistance to enzymatic degradation while preserving receptor binding (src-15, src-16).

Several profiles contrast its mechanism with botulinum toxin: they state it acts upstream at the receptor level (presynaptically) rather than by cleaving SNARE proteins, and describe it as preserving partial muscle motility and avoiding the frozen appearance associated with injections (src-23, src-39). Profiles also distinguish it from Argireline (Acetyl Hexapeptide-8) and SNAP-8 (Acetyl Octapeptide-3), which are described as acting post-synaptically on SNARE complex assembly (src-18).

Reported clinical and preclinical findings

  • The MDPI review reports that three emulsions (0.5%, 1%, 2%) were formulated and applied at the mimic-muscle level over the corrugator supercilii (eyebrow zone) and orbicularis oculi (periorbital zone), with regression of wrinkles between the eyebrows evaluated using the pro-derm Analyser imagistic method (src-4, src-5, src-6).
  • The Dragomirescu et al. (2014) study (Cosmetics/MDPI, published 8 April 2014, vol. 1, pp. 75–81) describes Leuphasyl as a botox-like peptide applied topically at the mimic-muscle level, showing efficiency in reducing wrinkles between the eyebrows, reports an optimal application concentration, describes it as safe for topical use, and reports improvements in skin hydration, elasticity, and texture (src-11, src-50, src-51). A tier-3 profile attributes to this study a ~34.7% forehead wrinkle-depth reduction at 2% Leuphasyl over 60 days (src-7, src-38).
  • A tier-4 profile reports that manufacturer-sponsored split-face studies showed statistically significant reductions in crow's-foot wrinkle depth after 28 days of twice-daily topical application versus vehicle control, and that in vitro studies published in Cosmetics (MDPI, 2014) confirmed receptor-mediated modulation of Ca2+ channels consistent with enkephalin activity (src-25, src-26).
  • Reported wrinkle-reduction figures vary between sources and are worth reading with that caveat in mind. A vendor page reports 5% Leuphasyl reduced wrinkles by about 11% after 28 days, and about 25% (up to 47%) when paired with 5% Argireline (src-10); a tier-3 profile reports ~11–12% alone (src-9, src-37); and tier-4 profiles report up to 47% combined with Argireline and a 34.7% frontal wrinkle-depth reduction at a 2% minimum effective concentration (src-32). Manufacturer data reported across profiles indicates combining Leuphasyl with Argireline produces greater wrinkle reduction than either alone (src-19, src-34, src-42, src-45).

Additional reported activities (preclinical / in silico)

Computational and in vitro studies report interactions beyond the neuromuscular mechanism: binding to TGF-β, TNF-α, MAPK, PI3K/AKT and NF-κB targets implicated in skin aging (src-56), interactions with AKT-1 and MAPK14/p38α (src-31), and targeting of matrix metalloproteinases MMP-1, MMP-8 and MMP-13 with the strongest interaction reported for MMP-13 (src-62). An in silico study describes strong docking affinity to EGFR and PI3K and reports cytotoxic effects in MDA-MB-231 and PC3 cells in MTT assays, suggesting possible selective anticancer effects (src-58, src-59). Separately, in vitro work reports that adding terminal D-tyrosine to pentapeptide-18 conferred anti-melanogenic activity — reducing melanin content and tyrosinase activity in MNT-1 melanoma cells and primary melanocytes and in a 3D human skin model (src-54, src-55); a tier-3 profile likewise suggests potential melanin suppression and skin brightening in D-tyrosine-containing analogs (src-46). Formulation studies report that solid lipid nanoparticles/lipid nanocarriers can co-deliver retinol and pentapeptide-18 as a stable anti-aging combination, with semi-solid formulations showing reduced sebum secretion and reduced facial wrinkles (src-52, src-53, src-60).

Evidence caveats

Multiple sources note the clinical evidence base is thin and primarily manufacturer-sponsored; one tier-4 profile explicitly states that no independent peer-reviewed clinical trials existed as of 2026 (src-27). Reported wrinkle-reduction percentages and their associated concentrations are inconsistent across sources, and sources disagree on the INCI name (Pentapeptide-18 vs Pentapeptide-3) and whether the sequence contains D-alanine. Collagen/elastin enhancement (src-9) and skin-brightening (D-tyrosine analogs, src-16) claims rest on limited or analog-specific sourcing, and the anticancer, MMP, and aging-pathway findings are in silico or in vitro only.

What the research shows

149 findings extracted from the 20 sources cited below, strongest evidence first within each group. Every one links to the source it came from.

What human studies found

Based on 9 human study findings, 3 in vitro findings, 4 expert opinion findings, 2 anecdotal findings and 3 theoretical findings.

  • human studyLeuphasyl shows efficiency in reducing wrinkles between the eyebrows1

  • human studyLeuphasyl improves skin hydration, elasticity, and texture1

  • human studySemi-solid formulations enriched with retinol and oligopeptide-loaded lipid nanocarriers showed significant reduction in the level of sebum secretion (anti-acne therapy)2

  • human studySemi-solid formulations enriched with retinol and oligopeptide-loaded lipid nanocarriers showed a decrease in the number of facial wrinkles (anti-aging therapy)2

  • human studyRegression of wrinkles between eyebrows was evaluated using pro-derm Analyser imagistic method3

  • human studyCombined with other synaptic blockers, such as Argireline, it showed a potentiating effect, yielding more noticeable results9

  • human studyDragomirescu et al. (2014) reported ~34.7% forehead wrinkle-depth reduction at 2% over 60 days12

  • human studyClinical studies show 11-12% reduction in wrinkle depth13

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  • human studyManufacturer-sponsored clinical split-face studies report statistically significant reductions in crow's-foot wrinkle depth after 28 days of twice-daily topical application versus vehicle control19

  • in vitroLEUPHASYL reduces the depth of wrinkles on the face caused by contraction of muscles of facial expression, especially in the forehead and around the eyes4

  • in vitroLeuphasyl exhibited cytotoxic effects in MDA-MB-231 and PC3 cells in MTT assays5

  • in vitroLeuphasyl® is an enkephalin-like peptide that has proven effective in reducing expression wrinkles with an alternative mechanism to Botulinum toxin-like molecules9

  • expert opinion5% Leuphasyl reduced wrinkles ~11% after 28 days, and ~25% (up to 47%) when paired with 5% Argireline11

  • expert opinionPentapeptide-18 enhances collagen and elastin production13

  • expert opinionPegademase bovine (PEGylated bovine adenosine deamidase) was approved for enzyme replacement therapy for severe combined immunodeficiency16

  • expert opinionPegaspargase (PEGylated asparaginase) was approved for treatment of acute lymphoblastic leukaemia16

  • anecdotalPentapeptide-18 reduces wrinkle depth by ~11% alone12

  • anecdotalPentapeptide-18 reduces wrinkle depth up to 25% when combined with Argireline12

  • theoreticalClinical combination with Argireline achieves up to 47% wrinkle reduction15

  • theoreticalNo independent peer-reviewed clinical trials exist as of 2026; evidence base is primarily manufacturer-sponsored19

  • theoreticalManufacturer data reports that the combination of 5% Leuphasyl with 10% Argireline produces greater wrinkle reduction than either peptide alone20

How it works

Based on 4 human study findings, 18 in vitro findings, 22 expert opinion findings and 27 theoretical findings.

  • human studyLeuphasyl is a Botox-like peptide1

  • human studyLeuphasyl has neuromodulatory properties1

  • human studyLeuphasyl (Pentapeptide-18) mitigates wrinkle formation by inhibiting neurotransmitter release1

  • human studyLipid nanocarriers as components of cosmetic formulations may provide an opportunity to fully exploit the beneficial properties of pentapeptide-18 and retinol while reducing the undesirable effects that occur during retinoid therapy2

  • in vitroLEUPHASYL couples to the enkephalin receptor on the outside of nerve cells, initiating a conformational change that results in decreased nerve cell excitability and modulated acetylcholine release4

  • in vitroLeuphasyl showed strong binding affinity to EGFR with a docking score of -10.63 kcal/mol5

  • in vitroLeuphasyl showed binding to PI3K with a docking score of -9.15 kcal/mol5

  • in vitroLeuphasyl relies on hydrophobic interactions for EGFR binding with a binding energy of -46.68 kcal/mol5

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  • in vitroLeuphasyl showed stronger interactions with MMP-136

  • in vitroLeuphasyl targets matrix metalloproteinases (MMP-1, MMP-8, and MMP-13) which contribute to collagen breakdown6

  • in vitroPentapeptide-18 binds to TGF-β, TNF-α, MAPK, PI3K/AKT, and NF-κB targets implicated in skin aging7

  • in vitroSolid lipid nanoparticles (SLNs) incorporated with retinol and oligopeptide can have a full spectrum of effects on the skin as a compatible combination of ingredients with broad anti-aging properties8

  • in vitroLeuphasyl® is a pentapeptide (Pentapeptide-18) with sequence Tyr-D-Ala-Gly-Phe-Leu that modulates Ca2+ channels in vitro9

  • in vitroPentapeptide-18 acts similarly to natural enkephalins: it binds to the enkephalin receptor on the surface of nerve cells9

  • in vitroWhen Leuphasyl® couples to the receptor, a conformational change initiates a cascade inside the neuron that decreases its excitability and modulates the release of acetylcholine9

  • in vitroD-tyrosine is known to negatively regulate melanin synthesis by inhibiting tyrosinase activity10

  • in vitroPeptides containing terminal D-tyrosine can reduce the melanin contents of human melanocytes10

  • in vitroAddition of D-tyrosine to the terminus of pentapeptide-18 endowed the peptide with the ability to reduce melanin content and tyrosinase activity in human MNT-1 melanoma cells and primary melanocytes10

  • in vitroTerminal D-tyrosine-containing pentapeptide-18 inhibited melanogenesis induced by α-MSH treatment or UV irradiation of MNT-1 cells10

  • in vitroTerminal D-tyrosine-containing pentapeptide-18 reduced melanin synthesis in the epidermal basal layer of a 3D human skin model10

  • in vitroAddition of D-tyrosine to an anti-aging peptide (GEKG) or an anti-inflammatory peptide (GHK) endowed these short peptides with anti-melanogenic effects without altering their intrinsic effects10

  • in vitroIn vitro studies published in Cosmetics (MDPI, 2014) confirm receptor-mediated modulation of Ca2+ channels consistent with enkephalin activity19

  • expert opinionLeuphasyl inhibits neuromuscular synapses in mimic muscles, acting as enkephalins3

  • expert opinionLeuphasyl links the enkephalin receptor to nervous cells, thereby modulating the release of acetylcholine in synaptic space3

  • expert opinionThis cellular activity results in relaxation of muscle and reduction of expression wrinkles3

  • expert opinionLeuphasyl effectively reduces expression lines and fine wrinkles through neuromuscular relaxation, similar to the mechanism of botulinum toxin but applied topically11

  • expert opinionLeuphasyl promotes visibly smoother skin texture by relaxing repeated micro-contractions that contribute to surface roughness and creasing11

  • expert opinionPentapeptide-18 works upstream by mimicking the body's own inhibitory signaling, unlike Argireline or Syn-Ake12

  • expert opinionThe enkephalin/δ-opioid-receptor presynaptic inhibition mechanism is pharmacologically sound12

  • expert opinionPentapeptide-18 (Leuphasyl) is a five-amino-acid peptide that suppresses muscle contractions causing expression lines by inhibiting acetylcholine release at the neuromuscular junction13

  • expert opinionPentapeptide-18 reduces glutamate release supporting facial expression smoothing13

  • expert opinionSynergistic effects when combined with Argireline which targets different neural pathways13

  • expert opinionPotential melanin suppression in D-tyrosine-containing analogs supporting skin brightening13

  • expert opinionMimics the natural mechanism of enkephalins to reduce the excitability of neurons13

  • expert opinionInhibits calcium influx across the neuron membrane to reduce glutamate release and muscle contraction13

  • expert opinionPeptides exhibit unique and powerful pharmacology that has not been possible to effectively mimic with either small molecules or antibodies16

  • expert opinionPEGylation increases peptide half-life by decreasing the rate of renal filtration16

  • expert opinionPEGylation was originally conceived as a modification to prevent the recognition of foreign proteins by the immune system16

  • expert opinionPEGylation improved the pharmacokinetics of proteins by making drug molecules larger, leading to the drug being filtered more slowly by the kidneys16

  • expert opinionPEGylation can make proteins or peptides more water-soluble and protect them from degradation by proteolytic enzymes16

  • expert opinionPEGylation can reduce the affinity of therapeutic proteins to their cognate cellular receptors16

  • expert opinionPEG is attached to the -amino groups of lysine on the surface of proteins or peptides at high pH16

  • expert opinionAt high pH (8.0 or higher), lysine side chain amino groups are covalently attached to PEG through N-hydroxy succinimides16

  • expert opinionFirst-generation PEGylation methods typically result in a family of products containing different numbers of PEG chains attached at different sites on a protein rather than a single discrete product16

  • theoreticalPentapeptide-18 (Leuphasyl®) has neuromodulatory properties7

  • theoreticalPentapeptide-18 mitigates wrinkle formation by inhibiting neurotransmitter release7

  • theoreticalPentapeptide-18 is a synthetic enkephalin-mimicking pentapeptide that reduces acetylcholine release at the neuromuscular junction, relaxing facial muscles and smoothing expression wrinkles12

  • theoreticalPentapeptide-18 binds to opioid receptors on presynaptic nerve terminals, triggering a G-protein cascade that closes calcium channels and opens potassium channels12

  • theoreticalD-alanine substitution at position 2 improves enzymatic stability12

  • theoreticalPeptides are a class of molecules that fall between small organic compounds and large biological molecules due to their distinct size, structure, and bioactivity14

  • theoreticalPeptides are considered as 'building blocks' of proteins, with smaller size and usually absence of higher order structures comparing to proteins14

  • theoreticalPeptides are ubiquitous in cells and tissues throughout human body, where they are actively involved in vital physiological processes14

  • theoreticalLeuphasyl (Pentapeptide-18; Tyr-D-Ala-Gly-Phe-Leu) is a synthetic acetylated pentapeptide structurally modeled on leu-enkephalin with a D-alanine substitution at position 2 to confer enhanced proteolytic stability15

  • theoreticalLeuphasyl functions as a partial agonist at delta-opioid receptors (DOR/OPRD1) expressed on presynaptic motor nerve terminals innervating facial musculature15

  • theoreticalUpon DOR binding, Leuphasyl activates inhibitory Gi/Go-coupled signaling cascades that release Gα(i) and Gβγ subunits intracellularly15

  • theoreticalGβγ subunits directly bind and close N-type voltage-gated calcium channels (Cav2.2/CACNA1B) at the presynaptic terminal, preventing Ca2+-dependent vesicle fusion15

  • theoreticalGβγ-mediated opening of G protein-coupled inwardly rectifying potassium channels (GIRK/Kir3.x) hyperpolarizes the nerve terminal, further reducing excitability15

  • theoreticalCombined Ca2+ channel closure and K+ channel opening inhibits SNARE complex-mediated exocytosis of acetylcholine-containing synaptic vesicles, reducing acetylcholine release into the synaptic cleft15

  • theoreticalPentapeptide-18 exhibits direct molecular interactions with dermal aging-related proteins including TGF-β receptor type I (ALK5), TNF-α, AKT-1, and MAPK14 (p38α MAP kinase)15

  • theoretical2026 computational studies reveal anti-inflammatory and ECM-preserving activities that operate independently of the neuromuscular mechanism15

  • theoreticalClassified under the INCI name Pentapeptide-18, it is an enkephalin analog that modulates calcium channel activity in nerve terminals19

  • theoreticalLeuphasyl mimics endogenous enkephalins by binding to opioid receptors on the presynaptic membrane of neuromuscular junctions19

  • theoreticalReceptor binding triggers a conformational change that initiates an intracellular cascade reducing nerve cell excitability19

  • theoreticalThis dampens the calcium-dependent vesicular release of acetylcholine at the neuromuscular junction, attenuating the intensity of facial muscle contractions that produce expression lines19

  • theoreticalUnlike botulinum toxin, Leuphasyl acts upstream at the receptor level rather than by cleaving SNARE proteins, preserving partial muscle motility and avoiding the frozen appearance associated with injections19

  • theoreticalLeuphasyl is based on the natural enkephalin opioid pentapeptides -- leucine-enkephalin (Tyr-Gly-Gly-Phe-Leu) and methionine-enkephalin (Tyr-Gly-Gly-Phe-Met) -- first identified by Hughes et al. in 197520

  • theoreticalThe D-alanine substitution at position 2 in Leuphasyl increases resistance to enzymatic degradation while maintaining receptor binding affinity, as endogenous peptidases typically recognize only L-amino acid substrates20

  • theoreticalLeuphasyl is classified as a neurotransmitter-inhibiting peptide, specifically targeting the pre-synaptic side of the neuromuscular junction20

  • theoreticalEnkephalins modulate neurotransmitter release by binding to opioid receptors (primarily delta-opioid receptors) on nerve terminals, where they activate G-protein-mediated inhibition of voltage-gated calcium channels20

  • theoreticalLeuphasyl mimics the pre-synaptic inhibitory mechanism in the context of facial motor neurons, theoretically reducing the frequency and intensity of muscle contractions that produce expression wrinkles20

  • theoreticalLeuphasyl acts pre-synaptically while Argireline (Acetyl Hexapeptide-8) and SNAP-8 (Acetyl Octapeptide-3) act post-synaptically by interfering with SNARE complex assembly20

Dosing

Based on 2 human study findings, 5 expert opinion findings and 5 theoretical findings.

  • human studyAn optimal concentration of Leuphasyl exists for skin application1

  • human studyThree emulsions of different concentrations (0.5%, 1%, 2%) were formulated and applied to skin at mimic muscle level3

  • expert opinion2% Leuphasyl in formulation is the lowest concentration shown to give significant wrinkle reduction in cosmetic testing; 2% was the threshold at which measurable improvement appeared over ~2 months of daily use11

  • expert opinion2-4 weeks needed for visible wrinkle reduction with 4% concentration13

  • expert opinionPotent effects at 2% strength without irritation13

  • expert opinionTypically used as a topical solution (3%-10%)13

  • expert opinion28-60 days cycle length for measurable depth reduction13

  • theoreticalLEUPHASYL can be incorporated in cosmetic formulations such as emulsions, gels, sera at temperatures below 40°C4

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  • theoreticalIt is recommended that 3 to 10% of LEUPHASYL Solution is present in the final formulation to obtain significant anti-wrinkle activity4

  • theoretical2% minimum effective concentration produces 34.7% frontal wrinkle depth reduction15

  • theoreticalApplied in finished formulation at 1–5% concentration19

  • theoreticalManufacturer recommends combining with Argireline at equal concentration for enhanced effect19

How the body handles it

Based on 2 in vitro findings, 3 expert opinion findings and 3 theoretical findings.

  • in vitroADMET predictions indicated limited oral bioavailability and minimal BBB penetration for Leuphasyl5

  • in vitroSLN dispersions containing retinol and pentapeptide-18 maintained stability over 4 weeks of storage at different temperatures (4, 25, 45 °C)8

  • expert opinionLeuphasyl has limited bioavailability as a topical peptide with skin penetration challenged by hydrophilic nature and molecular size11

  • expert opinionLimited number of oral therapeutic peptide products and their poor absorption and subsequent low bioavailability indicate a need for new technologies to broaden the formulation design space14

  • expert opinionShort half-lives resulting from sensitivity to proteases and rapid renal clearance mean that peptide drugs tend to require frequent doses16

  • theoreticalLEUPHASYL Solution contains 0.5 g/L of peptide powder with 0.5% Caprylyl Glycol preservative4

  • theoreticalIn silico ADME and toxicity predictions suggested favorable pharmacokinetic and safety profiles for Leuphasyl6

  • theoreticalPentapeptide-18 has favorable ADMET properties (absorption, distribution, metabolism, excretion, and toxicity)7

Safety and side effects

Based on 3 human study findings, 2 in vitro findings, 3 expert opinion findings and 4 theoretical findings.

  • human studyLeuphasyl demonstrates safety for topical use1

  • human studyLipid nanoparticles reduce the irritating effect of retinol that is usually the case with classic retinoid therapies2

  • human studyEfficiency tests of Pentapeptide-18 showed that it is less effective than Botox injections, but it is safe, has no adverse effects, and preserves facial expressivity9

  • in vitroLeuphasyl showed no cytotoxicity on HaCaT cell line at concentrations up to 1 mg/mL6

  • in vitroThe MDPI study concluded Leuphasyl is safe with no adverse effects and preserves facial expressivity unlike botulinum toxin19

  • expert opinionWhether meaningful receptor engagement occurs through intact skin at cosmeceutical concentrations is the central unresolved question12

  • expert opinionComplete safety profile without neurological side effects13

  • expert opinionUsed topically; considered very safe with no reported systemic toxicity or significant skin irritation in standard cosmetic concentrations13

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  • theoreticalPentapeptide-18 is a safe, effective, and non-invasive candidate for advanced anti-aging skin care applications7

  • theoreticalRare skin irritation at high concentrations19

  • theoreticalContact sensitization (very rare)19

  • theoreticalLeuphasyl is not regulated as a drug by the FDA and is marketed as a cosmetic ingredient20

What people use it for

Based on 2 human study findings, 3 in vitro findings, 6 expert opinion findings and 3 theoretical findings.

  • human studyLeuphasyl can be applied topically to skin at the mimic muscle level1

  • human studyLeuphasyl was applied at eyebrow zone above corrugator supercilii muscle and periorbital zone above orbicularis oculi muscle3

  • in vitroLeuphasyl may exhibit selective anticancer effects5

  • in vitroLeuphasyl has potential to modulate aging-related pathways6

  • in vitroThe optimized dispersion of lipid nanoparticles incorporated with retinol and oligopeptide can be used as a cosmetic raw material ingredient with anti-aging properties8

  • expert opinionLeuphasyl is a botox-like peptide (pentapeptide-3) used in cosmetic science3

  • expert opinionLeuphasyl helps prevent formation of new expression lines with consistent use11

  • expert opinionLeuphasyl is applied topically to the skin as a cream, gel, or lotion and works mainly where it is put11

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  • expert opinionTherapeutic peptides administered as injectables remain the most commonly used dosage forms, particularly in the form of subcutaneous, intravenous, or intramuscular injections14

  • expert opinionTherapeutic peptide products may be delivered through administration routes including intranasal, implant, and sublingual routes14

  • expert opinionPeptides suffer from lack of oral bioavailability which necessitates injections16

  • theoreticalLEUPHASYL provides an additive or synergistic effect to complement the action of ARGIRELINE4

  • theoreticalPentapeptide-18 improves skin hydration, elasticity, and texture7

  • theoreticalMuscle contraction will be relaxed, and therefore, expression wrinkles will be diminished9

Other findings

Based on 2 human study findings, 1 in vitro finding, 4 expert opinion findings and 4 theoretical findings.

  • human studySemi-solid preparations were determined to be stable regardless of their storage temperature2

  • human studyA temperature of 25 °C was considered the recommended storage temperature for the tested semi-solid formulations2

  • in vitroLeuphasyl (Tyr-Ala-Gly-Phe-Leu) is derived from botulinum neurotoxin as a biomimetic peptide5

  • expert opinionMolecular formula C29H39N5O711

  • expert opinionAmino acid sequence H-Tyr-D-Ala-Gly-Phe-Leu-OH11

  • expert opinionPentapeptide-18 (Leuphasyl) was developed by Lipotec S.A. in Barcelona in the mid-2000s12

  • expert opinionTherapeutic peptides are formulated to achieve prolonged release, often through the use of polymer carriers14

  • theoreticalLEUPHASYL is a pentapeptide synthesized following cGMP guidelines with a final freeze-drying step4

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  • theoreticalLEUPHASYL Solution must be kept in a cool, dark place with shelf life of at least twelve months, or at 4°C for at least eighteen months4

  • theoreticalLeuphasyl is a synthetic pentapeptide (Tyr-D-Ala-Gly-Phe-Leu) developed by Lipotec as a cosmeceutical anti-wrinkle active19

  • theoreticalLeuphasyl (Pentapeptide-18) has the sequence Tyr-D-Ala-Gly-Phe-Leu and was developed by Lipotec (now Lubrizol) as a cosmeceutical anti-wrinkle ingredient20

Points of contention

Where the evidence is unsettled, thin, or says less than the popular claim — worth knowing before you draw conclusions.

Limited evidence

The clinical evidence base is thin and largely manufacturer-sponsored.

The peptahub profile explicitly states that no independent peer-reviewed clinical trials existed as of 2026 and the evidence base is primarily manufacturer-sponsored split-face studies; several efficacy figures are attributed to manufacturer data rather than independent trials.

Contested

Reported wrinkle-reduction percentages and their concentrations vary between sources.

Sources give inconsistent figures: ~11% at 5% alone (Leuphasyl Dosing, Need to Know Information, Safety,…, Pentapeptide-18 (Leuphasyl, Tyr-D-Ala-Gly-Phe-Leu, Enkephalin Mimetic Peptide) | Peptide List), 11–12% generally (Pentapeptide-18 (Leuphasyl) Research, Dosing & Protocols | Peptides.ID), ~34.7% at 2% over 60 days (Leuphasyl - Neemio, Pentapeptide-18 (Leuphasyl, Tyr-D-Ala-Gly-Phe-Leu, Enkephalin Mimetic Peptide) | Peptide List), and combined-with-Argireline results reported as ~25% (Leuphasyl Dosing, Need to Know Information, Safety,…, Pentapeptide-18 (Leuphasyl, Tyr-D-Ala-Gly-Phe-Leu, Enkephalin Mimetic Peptide) | Peptide List) or up to 47% (Leuphasyl Dosing, Need to Know Information, Safety,…, Leuphasyl - Neemio). Concentrations tied to effect also differ (2% vs 5% as effective thresholds).

Contested

Sources disagree on the INCI name and exact sequence.

Most sources call it Pentapeptide-18 with sequence Tyr-D-Ala-Gly-Phe-Leu, but the MDPI review and the manufacturer TDS refer to it as pentapeptide-3 / INCI Pentapeptide-3, and one PubMed study lists the sequence as Tyr-Ala-Gly-Phe-Leu (without the D-alanine).

Limited evidence

Skin penetration through intact skin is an unresolved question.

Multiple sources note limited topical bioavailability from the peptide's hydrophilic nature and molecular size (Leuphasyl Dosing, Need to Know Information, Safety,…), limited oral bioavailability and minimal BBB penetration in ADMET modeling (In Vitro and In Silico Assessment of Anticancer Activity of Venom-Derived and Biomimetic Neurotransmitter Inhibitor Pentapeptides.), and one profile flags whether meaningful receptor engagement occurs through intact skin at cosmeceutical concentrations as the central unresolved question (Pentapeptide-18 (Leuphasyl, Tyr-D-Ala-Gly-Phe-Leu, Enkephalin Mimetic Peptide) | Peptide List).

Single source

Collagen/elastin enhancement and melanin-suppression skin-brightening claims rest on limited sourcing.

The claim that Leuphasyl enhances collagen and elastin production appears only in a tier-3 profile (Pentapeptide-18 (Leuphasyl) Research, Dosing & Protocols | Peptides.ID). The anti-melanogenic activity is demonstrated only for D-tyrosine-modified analogs in in vitro/3D-skin models (D-tyrosine adds an anti-melanogenic effect to cosmetic peptides.), not for standard Leuphasyl in humans.

Limited evidence

Anticancer and MMP/aging-pathway findings are in silico or in vitro only.

EGFR/PI3K binding and cytotoxicity in MDA-MB-231 and PC3 cells (In Vitro and In Silico Assessment of Anticancer Activity of Venom-Derived and Biomimetic Neurotransmitter Inhibitor Pentapeptides.), MMP targeting (Integrative In Silico and In Vitro Evaluation of Vialox and Leuphasyl Pentapeptides for Antiaging Applications.), and TGF-β/TNF-α/AKT/MAPK interactions (Leuphasyl - Neemio, Pentapeptide-18 as an anti-aging candidate: Spectroscopic characterization and molecular interaction analysis.) come from docking, molecular dynamics, and cell-line assays, not human studies.

What you may have heard

The detailed nerve-signaling steps described for Leuphasyl are a theoretical extrapolation from opioid biology, not something shown to occur at the facial muscle junction.

Several vendor and aggregator profiles describe Leuphasyl as acting through a precise molecular cascade — binding delta-opioid receptors on motor nerve terminals, activating inhibitory Gi/Go proteins, closing N-type (Cav2.2) calcium channels, and opening GIRK potassium channels to shut down acetylcholine release. These specifics are borrowed by analogy from how enkephalins are known to dampen neurotransmitter release elsewhere in the nervous system; no study has confirmed that these particular receptors and ion channels operate this way at the human facial neuromuscular junction, where nerve-to-muscle signaling is cholinergic. The manufacturer's own technical data sheet claims only that the peptide 'modulates' acetylcholine release from neuron cell cultures in vitro. In short, the confident channel-by-channel mechanism is a plausible hypothesis, not an established pathway.

Using it with other compounds

Check a stack
  • MatrixylComplementary

    May be complementary

    These target skin aging through completely different routes: Leuphasyl relaxes the muscle movement that etches expression lines, while Matrixyl (Pal-KTTKS) signals fibroblasts to build collagen and rebuild the dermal matrix. Combining a muscle-relaxer with a matrix-builder addresses both dynamic and structural wrinkles, a common complementary cosmetic pairing.

    Tier 3Largely anecdotal — commonly discussed

    What the research doesn't fully establish

    The mechanisms clearly establish complementarity on the dermal_matrix dimension. Leuphasyl's primary mechanism is neuromuscular (inhibiting acetylcholine release to prevent dynamic wrinkle formation), while Matrixyl's mechanism is fibroblast-driven matrix synthesis (stimulating collagen and ECM production for structural support). Both peptides are tagged with dermal_matrix, and their mechanisms operate through distinct pathways: Leuphasyl via Gi/Go signaling and calcium channel inhibition at the neuromuscular junction, Matrixyl via matrikine signaling and TGF-β pathways in fibroblasts. The explanation accurately characterizes them as addressing different wrinkle etiology (dynamic vs. structural), which is a valid complementary relationship. The proposed pairing aligns with the documented mechanisms without contradiction.

    Timing Topical; apply together or layer.

    Shares dermal matrix

  • SNAP-8Complementary

    May be complementary

    SNAP-8 is an extended Argireline that blocks SNARE-complex assembly to reduce acetylcholine release, while Leuphasyl reduces the same release presynaptically through enkephalin/Gi signaling. Different molecular handles on the same neuromuscular relaxation goal, so they can complement each other in an anti-wrinkle topical rather than being redundant.

    Tier 3Largely anecdotal — commonly discussed

    What the research doesn't fully establish

    Both peptides' mechanisms clearly target acetylcholine release reduction at the neuromuscular junction through distinct molecular pathways: Leuphasyl acts presynaptically via enkephalin receptor/Gi signaling and voltage-gated calcium channel inhibition (reducing calcium influx needed for exocytosis), while SNAP-8 acts by competitive inhibition of SNARE-complex assembly (blocking the final fusion machinery). These are mechanistically orthogonal approaches to the same endpoint (reduced acetylcholine release), which justifies the 'complementary' relationship type. Both are explicitly tagged with 'acetylcholine_pathway' and their mechanisms do not overlap or contradict—they represent different nodes in the same signaling cascade. The explanation accurately reflects the provided mechanism material.

    Timing Topical; apply together.

    Shares acetylcholine pathway

  • Palmitoyl Tetrapeptide-7Complementary

    No documented conflict

    Both are topical cosmetic peptides that improve skin appearance through different routes: Leuphasyl relaxes expression-line muscle signaling (and has reported minor matrix effects), while Palmitoyl Tetrapeptide-7 targets dermal-matrix protection and inflammation. Combining a wrinkle-relaxant with a matrix-protecting/anti-inflammatory peptide addresses distinct causes of aging skin.

    Tier 4Theoretical — not established

    What the research doesn't fully establish

    Both peptides are tagged with 'dermal_matrix' in their approved tags, establishing the shared dimension. The mechanisms clearly support complementary action: Palmitoyl Tetrapeptide-7 directly protects extracellular matrix (inhibits MMP-1, stimulates laminin/nidogen, suppresses IL-6/IL-1β inflammatory pathways), while Leuphasyl's primary mechanism targets neuromuscular relaxation and acetylcholine modulation (with secondary in silico evidence for MMP inhibition and TGF-β modulation). The proposed explanation accurately reflects these distinct but non-overlapping pathways—one addressing inflammation and matrix degradation, the other addressing dynamic wrinkle formation through muscle relaxation. The relationship type 'complementary' is justified by the mechanisms showing different routes to skin improvement without direct redundancy.

    Timing Topical; no timing conflict.

    Shares dermal matrix

  • Palmitoyl Tripeptide-1Complementary

    May be complementary

    Palmitoyl Tripeptide-1 (Pal-GHK) stimulates collagen, elastin and matrix synthesis through matrikine/TGF-β signaling, a structural route that is different from Leuphasyl's muscle-relaxing action. Pairing dermal-matrix building with dynamic-line relaxation targets wrinkles from two independent angles.

    Tier 3Largely anecdotal — commonly discussed

    What the research doesn't fully establish

    Both peptides' mechanisms justify the complementary relationship on the shared dimensions of dermal_matrix and collagen_synthesis. Leuphasyl targets dermal_matrix through acetylcholine pathway inhibition (reducing dynamic wrinkles via neuromuscular relaxation) and has approved tag 'dermal_matrix'. Palmitoyl Tripeptide-1 directly stimulates collagen types I, III, IV, VII synthesis and matrix components (elastin, fibronectin, GAGs, hyaluronic acid) via TGF-β/matrikine signaling with approved tags 'collagen_synthesis' and 'dermal_matrix'. The mechanisms describe mechanistically distinct pathways: Leuphasyl works through Gi/Go signaling and calcium channel inhibition affecting acetylcholine release, while Palmitoyl Tripeptide-1 works through integrin and TGF-β receptor activation of Smad-dependent collagen transcription. Both target wrinkle reduction but through independent mechanisms (dynamic relaxation vs. structural matrix building), supporting the complementary characterization.

    Timing Topical; apply together.

    Shares dermal matrix · collagen synthesis

  • SYN-AKEComplementary

    May be complementary

    SYN-AKE relaxes mimic muscles by blocking the postsynaptic nicotinic acetylcholine receptor, whereas Leuphasyl works on the presynaptic side to cut acetylcholine release. Attacking both sides of the neuromuscular junction converges on the same visible outcome — reduced expression lines — making them complementary in a smoothing topical.

    Tier 3Largely anecdotal — commonly discussed

    What the research doesn't fully establish

    The mechanisms clearly establish complementary action at the neuromuscular junction. Leuphasyl targets presynaptic enkephalin/delta-opioid receptors leading to inhibition of acetylcholine release via Gi/Go signaling and calcium channel inhibition. SYN-AKE targets postsynaptic muscular nicotinic acetylcholine receptors to block signal transmission. Both peptides are documented to reduce expression lines through neuromuscular relaxation, but via opposing sides of the synapse. The shared dimension 'acetylcholine_pathway' is explicitly supported: Leuphasyl has the approved tag 'acetylcholine_pathway' and mechanisms describing SNARE-mediated acetylcholine exocytosis inhibition; SYN-AKE has the approved tag 'acetylcholine_pathway' and mechanisms describing postsynaptic nicotinic acetylcholine receptor signaling. The explanation accurately reflects the dual-site mechanism described in both peptides' documentation, making this a well-justified complementary relationship.

    Timing Topical; can be layered together.

    Shares acetylcholine pathway

  • ArgirelineComplementary

    May be complementary

    Leuphasyl reduces acetylcholine release through an enkephalin/opioid presynaptic route (Gi-coupled calcium-channel inhibition), whereas Argireline blocks SNARE-mediated vesicle fusion — two different upstream brakes on the same neuromuscular junction. Vendor and formulation sources specifically report an additive/synergistic wrinkle effect when the two are combined topically.

    Tier 3Largely anecdotal — commonly discussed

    What the research doesn't fully establish

    Both peptides' mechanisms clearly target the acetylcholine pathway at the neuromuscular junction but via distinct upstream mechanisms: Argireline directly inhibits SNARE-complex-mediated vesicle fusion (blocking the final exocytosis step), while Leuphasyl reduces calcium influx via enkephalin/opioid receptor signaling and voltage-gated calcium channel inhibition (blocking an earlier step in the release cascade). These are mechanistically complementary interventions on the same pathway. Both peptides are explicitly tagged with 'acetylcholine_pathway,' and the mechanism descriptions support independent but convergent effects on acetylcholine release. The proposed explanation aligns with the provided mechanisms, and the vendor-reported additive/synergistic effect is consistent with dual inhibition at different points in the same signaling cascade.

    Shares acetylcholine pathway

Safety and side effects

Safety and Side Effects

Leuphasyl is not regulated as a drug by the FDA and is marketed as a cosmetic ingredient (src-20).

Sources generally characterize it as well tolerated at cosmetic concentrations:

  • A tier-4 profile states that the MDPI study concluded Leuphasyl is safe with no adverse effects and preserves facial expressivity unlike botulinum toxin (src-27), and an ingredient guide similarly reports that efficiency tests showed it is less effective than Botox injections but is safe, has no adverse effects, and preserves facial expressivity (src-42).
  • A tier-3 profile describes a complete safety profile without neurological side effects, characterizing it as very safe with no reported systemic toxicity or significant skin irritation at standard cosmetic concentrations (src-47).
  • The Dragomirescu et al. study reports Leuphasyl demonstrates safety for topical use (src-51).
  • In vitro toxicity work reports no cytotoxicity on the HaCaT keratinocyte cell line at concentrations up to 1 mg/mL, and in silico ADME/toxicity predictions suggesting favorable pharmacokinetic and safety profiles (src-63); another study reports favorable ADMET properties (src-57).

Reported potential adverse effects

A tier-4 profile lists rare skin irritation at high concentrations and very rare contact sensitization as potential adverse effects (src-28). Formulation studies report that lipid nanoparticles reduced the irritating effect of retinol seen in classic retinoid therapies when the two were co-formulated (src-61).

Important caveats

  • Bioavailability through intact skin is unresolved. A vendor page notes limited topical bioavailability owing to the peptide's hydrophilic nature and molecular size (src-12), and ADMET modeling indicated limited oral bioavailability and minimal blood-brain-barrier penetration (src-59). A tier-3 profile flags whether meaningful receptor engagement occurs through intact skin at cosmeceutical concentrations as the central unresolved question (src-40).
  • In vitro cytotoxicity note. An in silico/in vitro study reports Leuphasyl exhibited cytotoxic effects in MDA-MB-231 and PC3 cancer cell lines in MTT assays, framed as a possible selective anticancer effect rather than a toxicity concern (src-59); this is a cell-line finding, not a human safety observation.
  • The safety statements above derive largely from manufacturer-sponsored or in silico/in vitro sources, with no independent peer-reviewed clinical trials reported as of 2026 (src-27).

Reconstitution and handling

Dosing and Formulation

No medical dose has been established for Leuphasyl. It has no regulatory drug label — it is marketed as a topical cosmetic ingredient (src-20). The figures below are what the sources report for cosmetic formulation and use, not medical guidance, and reported effective concentrations vary between sources.

Topical formulation concentrations (as reported)

  • The MDPI review reports three emulsions formulated at 0.5%, 1%, and 2% applied to the skin at the mimic-muscle level (src-4).
  • A vendor page states 2% Leuphasyl is the lowest concentration shown to give significant wrinkle reduction in cosmetic testing, with measurable improvement over roughly 2 months of daily use (src-9), and describes topical application as a cream, gel, or lotion that works mainly where placed (src-11).
  • A tier-4 profile states finished formulations use 1–5% concentration, with the manufacturer recommending combination with Argireline at an equal concentration for enhanced effect (src-24).
  • A tier-3 profile suggests typical topical use at 3–10%, potent effects at 2% without irritation, ~2–4 weeks for visible wrinkle reduction at 4%, and a 28–60 day cycle length, with example regimens of 5% twice daily for expression lines and 10% once daily at night (src-48). These figures come from a community/expert-opinion profile, not from a trial.

Manufacturer technical data sheet (LEUPHASYL Solution)

The manufacturer TDS states LEUPHASYL is synthesized under cGMP with a final freeze-drying step and incorporated into emulsions, gels, and sera at temperatures below 40 °C, recommending 3 to 10% of LEUPHASYL Solution in the final formulation for significant anti-wrinkle activity (src-35). The Solution is described as containing 0.5 g/L peptide powder (0.05% powder) with 0.5% Caprylyl Glycol preservative, with a shelf life of at least twelve months at room temperature or eighteen months at 4 °C; the TDS lists the INCI name as Pentapeptide-3 (src-36).

Storage and handling (as reported)

  • A tier-3 profile provides storage guidance: -20 °C or below for freezer storage (ideally -80 °C for long-term, up to 2–3 years), 2–8 °C for short-term storage, use of reconstituted solutions within 4 weeks (28 days) for optimal potency, and mentions a 0.9% benzyl alcohol preservative (src-49).
  • Formulation studies report that lipid nanoparticle dispersions of retinol and pentapeptide-18 remained stable over 4 weeks of storage at 4, 25, and 45 °C (src-52), and that semi-solid preparations were stable regardless of storage temperature with 25 °C recommended (src-61).

Combination use

Multiple sources report an additive or synergistic effect when Leuphasyl is combined with Argireline (Acetyl Hexapeptide-8), with combined regimens reported to reach greater wrinkle reduction than either alone (src-10, src-19, src-24, src-34, src-42, src-45). No human trial in the provided claims has independently validated any of these formulation regimens outside manufacturer-sponsored studies.

What these percentages actually mean

The percentage figures across these sources are not directly comparable, because they may refer to two different things. The manufacturer's technical data sheet supplies Leuphasyl as a dilute trade solution that contains only 0.05% actual peptide powder, and its recommendation of 3–10% of that solution in a final formulation therefore works out to only roughly 0.0015–0.005% peptide by weight in the finished product. Vendor and community figures quoted as "2%", "5%", or "10% Leuphasyl" do not state whether they mean percent of the dilute trade solution or percent of pure peptide. If they refer to the trade solution — as the manufacturer's own numbers do — the true peptide dose is far lower than the headline percentage implies. Because the sources do not reconcile this point, the concentration figures reported here should be read with that ambiguity in mind.

Sources

Ordered by evidence quality — the strongest first.

  1. [PDF] The Efficiency and Safety of Leuphasyl—A Botox-Like Peptide | Semantic Scholar(opens in a new tab)
    Tier 1Web · semanticscholar.org
  2. Retinol and Oligopeptide-Loaded Lipid Nanocarriers as Effective Raw Material in Anti-Acne and Anti-Aging Therapies.(opens in a new tab)
    Tier 1PubMed · pubmed.ncbi.nlm.nih.gov · 2024
  3. The Efficiency and Safety of Leuphasyl—A Botox-Like Peptide(opens in a new tab)
    Tier 1Web · mdpi.com · 2014
  4. LEUPHASYL(opens in a new tab)
    Tier 2Web · daltosur.com
  5. In Vitro and In Silico Assessment of Anticancer Activity of Venom-Derived and Biomimetic Neurotransmitter Inhibitor Pentapeptides.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2026
  6. Integrative In Silico and In Vitro Evaluation of Vialox and Leuphasyl Pentapeptides for Antiaging Applications.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2026
  7. Pentapeptide-18 as an anti-aging candidate: Spectroscopic characterization and molecular interaction analysis.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2026
  8. Solid Lipid Nanoparticles Incorporated with Retinol and Pentapeptide-18-Optimization, Characterization, and Cosmetic Application.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2024
  9. Leuphasyl® | Pentapeptide-18 | Cosmetic Ingredients Guide(opens in a new tab)
    Tier 2Web · ci.guide · 2022
  10. D-tyrosine adds an anti-melanogenic effect to cosmetic peptides.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2020
  11. Leuphasyl Dosing, Need to Know Information, Safety,…(opens in a new tab)
    Tier 3Web · peptideinitiative.com
  12. Pentapeptide-18 (Leuphasyl, Tyr-D-Ala-Gly-Phe-Leu, Enkephalin Mimetic Peptide) | Peptide List(opens in a new tab)
    Tier 3Web · peptidelist.org
  13. Pentapeptide-18 (Leuphasyl) Research, Dosing & Protocols | Peptides.ID(opens in a new tab)
    Tier 3Web · peptides.id
  14. Just How Prevalent are Peptide Therapeutic Products? A Critical Review(opens in a new tab)
    Tier 4Web · pmc.ncbi.nlm.nih.gov
  15. Leuphasyl - Neemio(opens in a new tab)
    Tier 4Web · neemio.com
  16. Long Live Peptides - Evolution of peptide half-life extension technologies and emerging hybrid approaches - Drug Discovery World (DDW)(opens in a new tab)
    Tier 4Web · ddw-online.com
  17. Peptide Half-Life Explained: Duration, Stability, and Research Protocols ...(opens in a new tab)
    Tier 4Web · peptideslabuk.com
  18. The Efficiency and Safety of Leuphasyl—A Botox-Like Peptide(opens in a new tab)
    Tier 4Web · researchgate.net
  19. Leuphasyl (Pentapeptide-18): Benefits, Use & Research(opens in a new tab)
    Tier 4Web · peptahub.com · 2026
  20. Leuphasyl (Pentapeptide-18): Research Evidence & Safety Profile | PeptideInsight(opens in a new tab)
    Tier 4Web · peptideinsight.com · 2026