Leuphasyl

Leuphasyl is Tyr-D-Ala-Gly-Phe-Leu, a D-alanine-substituted leu-enkephalin that resists rapid enzymatic breakdown. Enkephalin receptors on the presynaptic terminal, when engaged, reduce voltage-gated calcium entry and therefore the number of acetylcholine vesicles released per action potential. Argireline blocks the fusion machinery downstream of that; Leuphasyl reduces the trigger upstream, which is why Lipotec sells them together and claims greater combined effect than either alone. All of this is receptor pharmacology established in neurons; that it happens in a facial mimetic muscle after topical application is an inference, not a demonstration.

Targets: Presynaptic enkephalin receptors, Voltage-gated calcium channels, Acetylcholine release

• · Trade solution used at 2-5% of the formula. From raw powder, 0.05-0.1% w/w. Almost always co-formulated rather than used alone.

Work out your exact syringe units →

• rareIrritation

• synergyargireline — Marketed specifically as a pair; presynaptic release plus SNARE fusion.
• synergyvialox — Different points on the same neuromuscular pathway.

• · Expression-line photographs at 0 and 12 weeks.

Cosmetic ingredient (INCI Pentapeptide-18) approved worldwide.

• Lubrizol/Lipotec Leuphasyl technical dossier (other)

This one is more interesting than its evidence base deserves, because the underlying pharmacology is genuinely well worked out — just in a completely different context. Enkephalins are endogenous opioid peptides. Delta and mu opioid receptors sit on presynaptic terminals, and when engaged they couple through Gi/Go to two effects that both reduce transmitter release: they inhibit adenylyl cyclase, lowering cAMP and PKA activity, and, more importantly for this mechanism, they directly inhibit N-type and P/Q-type voltage-gated calcium channels via the Gbeta-gamma subunit. Less calcium entry per action potential means fewer vesicles fuse. That is textbook presynaptic inhibition and it is the reason opioids work at all. So the logic is clean: Argireline interferes with the fusion machinery, Leuphasyl reduces the calcium trigger upstream of it, and Lipotec sells them together claiming greater combined effect than either alone. The problem is the same as everywhere else in this group. Enkephalin receptor pharmacology has been characterised on neurons in a dish and in the central nervous system, not on the terminal branches of the facial nerve after a hexapeptide has been rubbed on the overlying skin. Whether opioid receptors are even present in useful density at the human facial neuromuscular junction, and whether any peptide reaches them, is unestablished. Recent independent computational and in-vitro work has begun characterising pentapeptide-18 as an anti-ageing candidate on its own terms, which is more than most of this class has.

Nothing dramatic — this is a well-tolerated, low-concentration ingredient that rarely irritates. The failure mode is expectation. People read about opioid receptors and calcium channel inhibition, correctly conclude that this is real neurophysiology, and incorrectly conclude that it therefore works on their forehead. The gap between established receptor pharmacology and demonstrated cosmetic effect is enormous here and is not bridged by any published human data. The second issue is that it is almost never sold alone, so if a combination product works you cannot attribute it, and if it does not you cannot say which component failed.

• Delta and mu opioid (enkephalin) receptors on the presynaptic terminal — Native leu-enkephalin binds delta receptors in the low nanomolar range; the D-Ala2 analogue is a well-characterised research ligand. No affinity has been published for the cosmetic application specifically.

  Gi/Go coupling inhibits adenylyl cyclase and, via Gbeta-gamma, directly inhibits N-type and P/Q-type voltage-gated calcium channels.

• N-type and P/Q-type voltage-gated calcium channels (indirect) — Not a direct binder

  Reduced calcium influx per action potential means fewer acetylcholine vesicles fuse. This is the actual output that would matter cosmetically.

Week 4-8: the manufacturer's claimed window for visible change with twice-daily use. Week 12: realistic assessment point. Given the absence of independent data, treat any timeline here as a marketing schedule rather than a pharmacological one.

Sold as the presynaptic partner to Argireline and almost never used alone — Lipotec's synergy panels are the entire commercial rationale for the pairing. Chemically it is compatible with everything at cosmetic pH. Combining it with Vialox or Syn-Ake gives you presynaptic release inhibition plus postsynaptic receptor blockade, which is the most mechanistically complete version of the topical neuromuscular stack and also the most expensive way to not reach a muscle. If you are going to run one of these peptides, the case for running four is weak; the case for spending the same money on a retinoid plus sunscreen is strong.

Against Argireline, Leuphasyl has better-established underlying receptor pharmacology and worse cosmetic evidence — Argireline at least has a published trial and a published penetration study. Against Syn-Ake and Vialox, Leuphasyl is presynaptic and those are postsynaptic, so combining is mechanistically sensible even if none of them has demonstrated delivery. Against botulinum toxin, no comparison. The one genuinely distinctive thing about Leuphasyl is that its mechanism is the only one in this group that has been rigorously validated in another field.

$12–$60/month. Raw pentapeptide-18 runs roughly $40-90 per gram, but it is used at 0.05-0.1%, so a gram lasts a long time. Finished products are almost always combination formulas at $15-60 a month. Market observation, not a sourced pricing study.

• ?Whether opioid receptors are present at useful density at the human facial neuromuscular junction has not been established.
• ?No permeation study of pentapeptide-18 into human skin exists.
• ?No independent human efficacy trial exists. The synergy-with-Argireline claim is entirely from Lipotec panels.
• ?The Tyr-D-Ala-Gly-Phe-Leu identity of INCI Pentapeptide-18 is consistently reported across cosmetic literature but I could not confirm it against a primary source in this session.
• ?The molecular weight of 569.6 Da in the Core record is consistent with that sequence but is unconfirmed against a primary source.

• Integrative In Silico and In Vitro Evaluation of Vialox and Leuphasyl Pentapeptides for Antiaging Applications Akhan D, Bicak B, Kurtur OB, Budama-Kilinc Y, Gunduz SK, Chemistry and Biodiversity, 2026 · PMID 42116636

  One of the very few independent academic evaluations of Leuphasyl, and it studies it head to head with Vialox.

• Pentapeptide-18 as an anti-aging candidate: Spectroscopic characterization and molecular interaction analysis Akhan D, Bicak B, Akalin E, Gunduz SK, Computational Biology and Chemistry, 2026 · PMID 41722287

  Structural and interaction characterisation of pentapeptide-18 specifically. Computational and spectroscopic, not clinical.

• In Vitro and In Silico Assessment of Anticancer Activity of Venom-Derived and Biomimetic Neurotransmitter Inhibitor Pentapeptides Akhan D, Bicak B, Akman G, Kecel Gunduz S, Cell Biochemistry and Biophysics, 2026 · PMID 42412310

  Same group, broader look at the neurotransmitter-inhibitor pentapeptides used in cosmetics.

• Usage of Synthetic Peptides in Cosmetics for Sensitive Skin Resende DISP, Ferreira MS, Sousa-Lobo JM, Sousa E, Almeida IF, Pharmaceuticals, 2021 · PMID 34451799

  Independent review that places the enkephalin-mimetic cosmetic peptides in context.