Lumekefamide (Tafalgin)_Dosage, benefits & legal status
Also known as Tafalgin, Taphalgin, [D-Arg2]dermorphin-(1-4) amide, Tyr-D-Arg-Phe-Gly-NH2
A prescription opioid peptide marketed as not an opioid.
Common vial size is what vendors typically sell, not a recommendation. Enter your own vial in the calculator.
What is Lumekefamide (Tafalgin)?
Plain language first. The technical label stays, but it never stands alone.Overview
This is a prescription painkiller sold in Russian pharmacies, given as an injection under the skin, and it is a real peptide with a real registration. The reason it needs a page is that almost everything said about its safety falls apart when you follow the citations. It is sold on the idea that it hits one half of the opioid system and leaves alone the half that causes addiction and breathing problems. That split does not exist in current pharmacology. The animal study of this exact molecule found physical dependence and says so in its title. The dramatic safety figures quoted for it were measured on two different compounds, one of them a 1985 study of a related peptide given into the spine. Even Russia's two main drug reference works cannot agree on whether this is an opioid.
Lumekefamide is a synthetic tetrapeptide analgesic, Tyr-D-Arg-Phe-Gly-NH2, registered in Russia for subcutaneous use in moderate to severe pain. Structurally it is dermorphin's first four residues, amidated, with D-arginine substituted for D-alanine at position 2, so it is correctly named [D-Arg2]dermorphin-(1-4)-amide. Its formula is C26H36N8O5 with a molecular weight near 540.6, and its three stereocenters are fully defined: L-tyrosine, D-arginine, L-phenylalanine. It is promoted as a selective mu-1 opioid receptor agonist that spares the mu-2 subtype said to cause respiratory depression and dependence. That framing rests on a receptor distinction modern pharmacology does not recognize, and no binding affinity for this compound at any opioid receptor appears in the published literature.
What it's used for
Registered in Russia for pain, including cancer pain, as a subcutaneous injection. It has no US approval and no verified registration in any other country.
How does Lumekefamide (Tafalgin) work?
What it does in the body, and where.Three separate questions get answered as one in the marketing: what receptor it binds, how selectively, and what that selectivity buys. Only the first has a clear answer.
- 01It is four sevenths of dermorphinDermorphin, already covered here, is Tyr-D-Ala-Phe-Gly-Tyr-Pro-Ser from frog skin. Take its first four residues, cap the end as an amide, and swap the mirror-image alanine at position 2 for a mirror-image arginine, and you have this molecule. Positions 1, 3 and 4 are dermorphin's own. The family resemblance is exact rather than loose, and it matters because much of the safety evidence quoted for this drug was measured on other members of the same family.
- 02The mu-1 claim does not survive contact with the receptorThere is one mu-opioid receptor gene, OPRM1. The mu-1 and mu-2 subtypes come from pharmacological experiments in the 1980s, and a standard anesthesia review describes the evidence for their legitimacy as deficient. So a claim to activate mu-1 while sparing mu-2 cannot be true as stated, because there is no mu-2 to spare. The single docking study of this compound docked it against a generic mu receptor, PDB entry 8E0G, for the simple reason that no mu-1 structure exists to dock against. No measured binding affinity for this compound at any opioid receptor was found in the published literature.
- 03A second target nobody advertisesIndependent academics in Russia found in 2024 that this compound is a positive allosteric modulator of acid-sensing ion channels, with half-maximal effects around 0.09 mM at rat ASIC3, 0.3 mM at human ASIC3 and 1 mM at ASIC1a. That matters because the injected product is 4 mg per mL, roughly 9 mM, so those concentrations are reachable where the needle goes. The authors warn about promiscuous effects. None of this appears in promotional material, and it is a plausible contributor to local pain relief that has nothing to do with opioid receptors.
- 04What the label describes is an opioidSet the mechanism claims aside and read the adverse effects. Sedation, nausea, vomiting, constipation and shortness of breath as common; pupil constriction and slow heart rate as uncommon; cautions in asthma and chronic obstructive pulmonary disease; contraindicated with other central nervous system depressants. That is the textbook opioid syndrome, and it is harder to reconcile with the marketing than any outside critique. Russia's own two major drug references disagree with each other: one classifies it as a non-opioid centrally acting analgesic, the other as an opioid non-narcotic analgesic with opioid action.
A schematic of the compound's mechanism, not a diagnostic image.
What else is it used for?
Each group carries its own evidence level.Approved means regulators have cleared it for that purpose. Investigational means it is in trials. Early research means it is being studied and is not established.
The receptor claim the whole product rests on
none- ReviewThere is one mu-opioid receptor gene, OPRM1. The mu-1 and mu-2 subtypes are 1980s pharmacological constructs whose legitimacy a standard review calls deficient, so sparing mu-2 is not a coherent claim.
- Lab studyThe single docking study used a generic mu receptor structure, because no mu-1 structure exists.
- No dataNo measured binding affinity for this compound at any opioid receptor was found in the published literature.
The safety numbers belong to other molecules
none- No dataThe quoted respiratory safety margin comes from data on a different dermorphin analog, as the developer's own conference abstract states.
- No dataThe zero respiratory depression finding comes from a 1985 study of dermorphin given into the spine: a different compound, a different route, and an enrollment figure that differs between the slide and its own reference list.
- No dataA non-addictive profile across more than 100,000 exposures is sourced to a sales and exposure database rather than to pharmacovigilance.
What was actually measured in this molecule
peer-reviewed-human- Animal studyPhysical dependence in rats, naloxone-precipitated, with weight loss on abrupt withdrawal, reported as less marked than morphine but present.
- Human trialRegistration phase 3: 179 patients, open-label against oral morphine, day 28 response 98.97% against 100.00%, p=0.6783.
- Human observationThe only patient series since: 37 people, observational, four hours of follow-up, no control arm, up to 95% already on other analgesics, adverse events in 19 of 37.
- Lab studyPositive allosteric modulation of acid-sensing ion channels at concentrations reachable at the injection site, a target absent from all promotional material.
Even the Russian references disagree
none- No dataOne major Russian drug reference classifies it as a non-opioid centrally acting analgesic; the other classifies it as an opioid non-narcotic analgesic with opioid action.
- RegulatoryIts own label lists sedation, nausea, vomiting, constipation and shortness of breath as common, with pupil constriction and slow heart rate as uncommon.
- RegulatoryA separate 2019 registration covers the active substance rather than the medicine, and coverage citing 2019 has merged the two records.
The central claim is that this drug activates the mu-1 opioid receptor while sparing mu-2, the subtype said to cause respiratory depression and addiction. There is one mu-opioid receptor gene and the subtype distinction is not accepted, so the claim cannot be true as stated; the phrasing has nonetheless propagated into roughly a dozen Russian journal titles and into the title of the 2026 patient series. The second error is that its headline safety figures describe this molecule. They do not: the respiratory safety margin was measured on a different dermorphin analog and the zero respiratory depression result comes from a 1985 study of dermorphin given into the spine, both per the developer's own abstract, while the non-addictive claim across 100,000 exposures rests on a sales database. The third is the claim of no dependence, when the one published study of this exact molecule is titled for the physical dependence it produced. The fourth is the 37-patient report being described as though it demonstrated effectiveness: it is observational, four hours long, uncontrolled, and up to 95% of its patients were already taking NSAIDs or strong opioids. Two smaller traps: the 2019 date in some coverage belongs to the active-substance record rather than the medicine's July 2022 registration, and claims of approval in Singapore trace to a conference abstract that two later company releases quietly decline to repeat.
The published record
Papers about Lumekefamide (Tafalgin)
Searched: lumekefamide, tafalgin, taphalgin.
Left out: dermorphin (the parent peptide, already covered on this site with its own slug. This molecule is literally dermorphin residues 1 to 4 amidated with D-Ala2 replaced by D-Arg2, and research suppliers catalog it under the dermorphin fragment name, so the two sets of literature merge without this rejection); DALDA (Tyr-D-Arg-Phe-Lys-NH2, one residue away at position 4, with its own separate pharmacology literature about peripheral selectivity); morphine (the comparator in the registration trial, with a literature spanning two centuries); opioid (the class term; the row must stay anchored on the molecule, not the receptor family); mu-opioid (the receptor, with a very large pharmacology literature that is not about this compound); ASIC (acid-sensing ion channels, a large ion channel literature; only one paper connects them to this molecule).
2 papers tagged human · 1 not reviews or lab · 0 clinical trial publications
1 registered trials · none with posted results
Furthest stage reached: Approved outside the US, Russia
Counted from Europe PMC indexing, not read by a person; a human tag can land on reviews, commentary or lab papers; clinical trial publications is the narrower count. A preprint and its journal version count once.
At a glance
Four things to know about Lumekefamide (Tafalgin)
Evidence
Clinical use
Category
Brain, mood and sleep
Common vial
Varies
Half-life
Not established in a source we could reach
How much, and do you cycle it?
The range, and whether you take breaks.4 mg per mL solution; the Russian label sets the regimen, as the label directs. Used for pain as needed rather than in cycles FDA label
An analgesic given for as long as the pain lasts. No cycling scheme applies, though tolerance and dependence are the relevant long-term questions for any opioid agonist.
Not established in a source we could reachNo figure
No half-life for this compound was found in any reachable published source. Phase 1 work in 39 healthy volunteers across doses from 0.05 to 7 mg exists, but its pharmacokinetic values are not in the literature that could be opened. Short peptides of this size are generally cleared quickly, and the label's dosing interval is the practical guide, but no figure is asserted here.
You can compare this against the whole library to see where it sits.
How is it given?
Dosing context and source notes.Supplied as a ready-made solution, so there is nothing to mix.
Supplied as a ready-made 4 mg per mL solution in ampoules, so there is nothing to reconstitute and the regimen comes from the Russian label rather than from community practice.
How do you store it?
Before mixing, and after.Follow the storage on the product label.
Lumekefamide (Tafalgin) is supplied as a finished product, so its label sets the storage. Pens, prefilled syringes, implants, tablets and ready-made solutions are used as supplied. Kits that include a powder are mixed just before the dose and usually used straight away, not kept for weeks. Many injectable products go in the fridge and must not be frozen, while others are kept at room temperature, so check the pack or ask the pharmacist.
What are the side effects and cautions?
Known cautions and warnings for this compound.Who should avoid it
- Any reliance on the claim that this spares the receptor subtype responsible for addiction and respiratory depression, since that subtype distinction is not recognized
- Treating the quoted respiratory safety margin as applying to this compound, because the figure was measured on a different dermorphin analog
- Assuming the absence of dependence, given a published dependence finding in the only study of this molecule
- Use alongside other central nervous system depressants or alcohol, per its own label
Stop and get help
- Slow, shallow or difficult breathing, the characteristic danger of this drug class
- Severe drowsiness or difficulty staying awake
- Signs of an allergic reaction, including swelling of the face or throat
Common effects
- Sedation, nausea and constipation, listed on the label as occurring in up to 1 in 10 people.
Where this page says nothing is established, that means nobody has studied it, not that a compound is safe.
Is Lumekefamide (Tafalgin) approved?
And where the numbers on this page come from.Not in the United States. Lumekefamide (Tafalgin) has no FDA approval. It is approved in Russia.
- Approval statusClinical use
- RouteUnder the skin (subcutaneous injection)
- Checked2 November 2026
- Approved outside the USRussia.This does not change the United States position above.
- DoseFrom the drug label. The manufacturer tested this range and a regulator reviewed it.
- Vial sizeFrom what vendors typically list; not a recommendation.
- SourcesBritish Journal of Pharmacology, physical dependence from a [D-Arg2] dermorphin tetrapeptideBJA Education, opioid receptorsOnkologiya. Zhurnal imeni P.A.Gertsena, efficacy and safety of Tafalgin in patients with cancer painProspective observational report in the "Saudi Journal of Anaesthesia"International Journal of Molecular Sciences, an opioid analgesic as a positive allosteric modulator of acid-sensing ion channelsFDA substance registration record for lumekefamide
What has happened recently
The Russian registration is real and two separate records get confused with each other. The finished medicine is registered as ЛП-№(001039)-(РГ-RU), dated July 19, 2022, re-registered December 5, 2024, held by ФармФирма Сотекс ЗАО, as a subcutaneous solution at 4 mg per mL with 2 mg and 3 mg presentations, status active, prescription only, ATC code N02BG. A separate record, ФС-001964 of November 5, 2019, registers the active substance under a different manufacturer; that is not the drug approval, and coverage citing a 2019 date or that manufacturer has merged the two. It does not appear to be scheduled in Russia: it is a plain prescription medicine with ATC N02B rather than N02A and no narcotic prescription form, although the controlled-substance lists could not be checked directly. Outside Russia nothing is verified. A conference abstract claims approvals in Russia and by Singapore's HSA, while two later and more formal company releases name no country at all, and Singapore is simply the developer's home base. In the US there is no approved application and no labeled product: an openFDA search returned nothing for this compound while the same query shape returned 28 records for morphine sulfate as a control. The company describes a completed pre-IND meeting only, and an IND itself would be confidential, so US trial status cannot be established either way. The company also states that the DEA determined the compound is not a controlled substance in March 2026, but that document is not published, and uncontrolled status is not an agency finding of low abuse potential. Note on sourcing: Russia's state register is closed to automated retrieval, so every registration field here was read from the major Russian drug reference mirrors rather than the register itself.
You can compare this against the whole library, or read how to check a seller.
What else is like Lumekefamide (Tafalgin)?
Others in Brain, mood and sleep, side by side.If you're weighing Lumekefamide (Tafalgin), it's worth reading Neuropeptide Y, P7C3, and Substance P in the same class.
A prescription opioid peptide marketed as not an opioid.
- Dose
- 4 mg per mL solution; the Russian label sets the regimen
- How often
- As the label directs
A hunger signal that refused to become a diet drug.
- Dose
- No established dose
- How often
- Not applicable
A neuroprotective molecule from a mouse screen. Never given to a person.
- Dose
- Research only
- How often
- No established pattern
Approved medicine blocks it. One paper suggests putting it on your face.
- Dose
- No established dose
- How often
- Not applicable
Guides for this compound
- How to Reconstitute a Peptide
Mix peptide powder with bacteriostatic water, step by step.
- How to Read an Insulin Syringe
Read the units, convert to millilitres, and draw the exact dose.
- mcg vs mg: The Peptide Dosing Mistake to Avoid
Your vial says mg and your protocol says mcg. Here is the conversion and how to check it.
Sources
- British Journal of Pharmacology, physical dependence from a [D-Arg2] dermorphin tetrapeptide(1988)Volume 95, pages 15 to 22, PMID 2905901. The only published study of this exact molecule, and its title states the finding: physical dependence was produced. In rats it was precipitated by naloxone and accompanied by weight loss on abrupt withdrawal, described as less marked than with morphine but present. Russian reference material nonetheless states an absence of physical and psychological dependence, sourced to a 14-day mouse study.
- BJA Education, opioid receptors(2015)Volume 15, pages 219 to 224. A standard review of opioid receptor pharmacology. It is cited here for one reason: it describes the evidence for the legitimacy of the mu-1 and mu-2 subtypes as deficient. There is a single mu-opioid receptor gene, OPRM1, so the central marketing claim for this drug rests on a distinction the field does not accept.
- Onkologiya. Zhurnal imeni P.A.Gertsena, efficacy and safety of Tafalgin in patients with cancer pain(2022)Volume 11, page 38. The randomized phase 3 behind the Russian registration, open-label across 5 centers, 179 patients in the intention-to-treat set, 120 on subcutaneous tafalgin against 59 on oral morphine, 143 per protocol. Day 28 analgesic response was 98.97% against 100.00%, p=0.6783. Note the limits: no PMID, Russian language, manufacturer funded, paywalled, absent from the international registries that could be reached, and paginated as a single page, so it may be a summary rather than a full report. Its reported pain scores are internally implausible and are not reproduced here.
- Prospective observational report in the "Saudi Journal of Anaesthesia"(2026)Volume 20, pages 23 to 26, PMID 41710625. The 37-patient report often described as evidence of effectiveness. It is prospective and observational, a single injection with four hours of follow-up and no control arm, and up to 95% of the patients were already taking NSAIDs or strong opioids, so the fall in pain scores cannot be attributed to this drug. Adverse events occurred in 19 of 37 patients, 51.3%. Its own title describes the drug as a mu-1 opioid receptor agonist.
- International Journal of Molecular Sciences, an opioid analgesic as a positive allosteric modulator of acid-sensing ion channels(2024)Volume 25, article 1413, PMID 38338690. Independent Russian academics report a second, non-opioid target: positive allosteric modulation of acid-sensing ion channels, with half-maximal effects near 0.09 mM at rat ASIC3, 0.3 mM at human ASIC3 and 1 mM at ASIC1a. The marketed solution is about 9 mM, so these are reachable at the injection site. The authors caution about promiscuous effects. Note also that the paper's title calls the compound an opioid analgesic, against one Russian reference work's classification of it as non-opioid.
- FDA substance registration record for lumekefamide(2026)UNII E2EN96EH7Y, CAS 100304-60-7, formula C26H36N8O5, molecular weight about 540.6. Absolute stereochemistry with three defined stereocenters: L-tyrosine, D-arginine, L-phenylalanine, ending in a glycinamide. The record also carries an INN code-system entry with the number 13308, though the list, the year and whether the name is proposed or recommended could not be established, and the developer never calls it an INN.
Beyond these, 4 records are indexed. Browse the records