Preloaded Autoinjector | Vilon | 3ml Pen | 6mg

The Vilon pen is a preloaded 3ml research autoinjector holding 6mg of the synthetic dipeptide L-lysyl-L-glutamic acid in solution, giving a concentration of 6/3 mg/ml. A dipeptide in water has one characteristic way of failing that longer peptides do not: the free N-terminus folds back onto the C-terminal carbonyl and closes the molecule into a six-membered ring, losing 18 daltons in the process.

Specification Table

What Changes When Vilon Ships in Solution?

Dissolving a dipeptide starts a reaction that has no equivalent in a longer chain: the N-terminal amine and the C-terminal carbonyl are close enough to reach each other, and in water they eventually do.

The chemistry is well established for dipeptides generally. The free alpha-amino group attacks the C-terminal carbonyl carbon, water leaves, and the two residues close into a 2,5-diketopiperazine, in this case cyclo(Lys-Glu). Being a condensation, the ring is 18 daltons lighter than the linear form: roughly 257.3 against 275.3. The reaction runs faster with heat and at neutral to basic pH, and slower cold and mildly acidic. Vilon diketopiperazine formation is therefore not an exotic risk but the expected behaviour of this molecular architecture in a standing aqueous fill.

Read what that means for a preloaded device. Concentration is fixed at manufacture, the solution then sits at 2-8°C for the life of the cartridge, and the ring-closure reaction proceeds the whole time at whatever rate the unpublished formulation pH sets. Nothing about the device stops it. A lyophilized cake in a sealed vial is largely protected, because the reaction needs water and molecular mobility, and a dry cake supplies neither.

The other degradation routes that dominate peptide stability discussions are simply absent here. There is no asparagine or glutamine, so classical deamidation cannot occur. There is no methionine, cysteine, tryptophan, tyrosine or histidine, so oxidation has no target and there is no disulfide to scramble. There is no aromatic ring, so photodegradation has no chromophore to work through and light protection is generic prudence rather than a mechanism.

Physical instability is equally quiet. Two amines against two carboxylates give a species close to charge-balanced at neutral pH, and a small zwitterion neither self-associates nor binds hard to anionic borosilicate glass. That is the opposite profile to a large cationic peptide, where adsorption and aggregation are the whole problem.

What is missing is data. No compound-specific aqueous stability study or preloaded-solution formulation study of this dipeptide was located, so the cyclisation route is asserted from general dipeptide chemistry rather than from a paper about this molecule. No Western-approved product exists, so there is no reference formulation whose buffer and pH choices could be read as a manufacturer’s answer to the question.

Does Vilon Come in a Pen, and What Does That Change?

Yes: this product is that pen, and the question worth asking is what a preloaded aqueous format changes for a molecule whose defining instability needs water to proceed.

Anyone asking does Vilon come in a pen is usually comparing against the Khavinson-institute norm, which is lyophilized powder reconstituted immediately before use. The parenteral work in the Russian literature used freshly prepared solution rather than material held for weeks, so a preloaded cartridge is a format the source literature never tested.

What the format removes is real: no diluent measured by hand, no incomplete dissolution, no adsorptive loss during transfer, and one concentration fixed at manufacture across every draw. The generic case is set out on the pen versus vial comparison and across the preloaded autoinjector range.

What it adds is time in water, and time in water is the only variable that drives the ring-closure reaction. That is the trade in one sentence, and for this compound it is unusually clean, because the format’s cost and the molecule’s weakness are the same thing.

What Does the Vilon Pen Deliver Per Increment?

Concentration is 6 mg divided by 3 ml, and because the molecular weight is only 275.3 g/mol, the molar figure that follows is high for the mass involved.

Molar concentration is (6/3 divided by 275.3) multiplied by 1000, which reduces to 6 × 1.211 mM. Mass per 0.01 ml, the smallest increment most pen mechanisms resolve, is (6/3) × 0.01 mg; per 0.1 ml it is (6/3) × 0.1 mg. At a 10 mg fill the numbers become concrete: 3.333 mg/ml, 12.11 mM, 33.3 micrograms per 0.01 ml and 333 micrograms per 0.1 ml.

The low molecular weight is worth pausing on, because it inverts an assumption people carry over from larger peptides. The same 10 mg of a 1300 g/mol decapeptide gives about 2.6 mM. Here it gives 12.11 mM, roughly 4.7 times the molar concentration, because the molecule is roughly 4.7 times lighter. Anyone planning in moles and buying in milligrams gets substantially more material than the mass suggests.

Against the published work the arithmetic cannot be anchored. The developer-group in vitro studies use low concentrations, commonly nanomolar to micromolar in culture, and reaching 1 micromolar from a 12.11 mM fill is about a 12,000-fold dilution. No human dose has been established for this compound in any controlled study, so there is no research figure for a device increment to be compared against, and any claim otherwise is unverified.

Vilon Pen vs Vial: What the Trade Actually Is

The Vilon pen vs vial decision here is unusually easy to state, because the two options differ on exactly one axis that matters for this molecule: how long the material spends dissolved before it is used.

A lyophilized vial presentation keeps the dipeptide dry until the day of the experiment, which is the only reliable way to stop ring closure, and it lets the cake be inspected before reconstitution. It costs a preparation step each time, with the volume error and transfer losses that come with it.

The cartridge inverts that. One preparation event at manufacture, identical draws thereafter, and a molecule that has been in water since the fill line. For a short study running over days, the calculation favours the device, since preparation variance dominates and cyclisation has had little time. For a device drawn on across two or three months it runs the other way, and faster than it would for a compound with a slower degradation route.

A nasal presentation of the same dipeptide exists and carries the same aqueous chemistry in a different container, so it is subject to the same argument.

Vilon Pen Storage and What Slows the Cyclisation

Store the device at 2-8°C, protected from light, and do not freeze it, because the reaction that matters here is thermally accelerated and refrigeration is the one intervention a laboratory controls.

Storage here is simpler than for most compounds in this catalogue, for an unusual reason: there is nothing to protect from light in any real sense. No aromatic residue means no near-UV chromophore, so bench illumination is doing no photochemistry to this molecule.

Temperature is the leading control. Every degree of warming speeds the ring closure, so a device left out between sessions accumulates degradant faster than one returned to the refrigerator, and the cumulative time at ambient temperature is worth recording rather than estimating. Freezing is a separate matter: it risks the cartridge and offers no benefit that refrigeration does not already provide for a molecule with no aggregation liability.

Formulation pH would be the other lever, since cyclisation accelerates at neutral to basic pH, but it is not disclosed on the product record and so cannot be factored into any Vilon pen storage plan. Record the date of first actuation and the interval to each subsequent draw. For a device used across weeks, that interval is an experimental variable.

What the Product Record Does Not State

Three fields are absent, and the first of them determines the rate of the only degradation reaction this compound has.

Solution pH is unpublished. Diketopiperazine formation is base-catalysed, so a formulation held mildly acidic behaves quite differently from one held at neutral pH, and the difference is a difference in shelf life rather than a technicality. Without the number, no estimate of degradant fraction at week twelve is possible even in principle.

The excipient system is unpublished. Whatever buffer species is present sets that pH and will enter any assay the solution is added to. For a compound this simple, the excipients may well outweigh the peptide in an assay by a wide margin.

Fill date, stability over shelf life, the counter-ion and the net peptide content are also absent. Acetate is the usual salt on the research market, and a gravimetric fill of an acetate salt contains less peptide than the nominal milligram figure implies, which matters more for a 275.3 g/mol molecule than for a large one because the counter-ion is a larger fraction of the total mass. All of it should be requested against the certificate of analysis, alongside the storage checks in peptide storage and stability.

Verifying the Device and Confirming Its Contents

This is one of the few compounds in the catalogue whose main degradation product announces itself, and that changes what a verification plan should look like.

Inspect the solution against a white background before each draw: clear, colourless, no particulate. Then accept that visual inspection has told you almost nothing, because both the linear dipeptide and its cyclic degradant are colourless and freely soluble, and neither produces haze.

Mass spectrometry is the method of choice here, and unusually it works. Vilon diketopiperazine formation produces a species 18 daltons lighter than the parent, roughly 257.3 against 275.3, and an 18 dalton gap is trivially resolved on any instrument worth using. That is a rare situation. Deamidation shifts mass by 1 dalton and oxidation states can be ambiguous; a clean minus 18 is unmistakable. Measuring the ratio of the two peaks in a drawn aliquot gives a direct read on how far the fill has travelled.

Chromatography completes the picture. The cyclic dipeptide is less polar than the zwitterionic linear form and separates from it readily on reversed phase, so an area-percent method run against a fresh reference gives quantitation to sit alongside the mass identification. Quantitation itself cannot use absorbance at 280 nanometres, since neither species has a tryptophan or tyrosine to absorb there, so use the peptide bond at 205 to 214 nanometres, a colourimetric assay, or amino acid analysis.

Equilibrate the cartridge to room temperature before use, because a spring-driven mechanism meters a cold, more viscous solution differently. A single gravimetric check of delivered volume onto a tared vessel establishes what the mechanism actually does.

What the Literature Reports and Where It Comes From

The published record is small, largely Russian-language, and traces almost entirely to one research lineage, which is the first thing a reader should know before weighing any of it.

The compound was developed by V. Kh. Khavinson and colleagues at the St Petersburg Institute of Bioregulation and Gerontology, and in indexed journals it usually appears as KE rather than under the trade name, which is why a PubMed search on the trade name returns so little. Khavinson and colleagues reported in 2001 that the dipeptide altered digestive-enzyme activity in rats of various ages. Kniaz’kin and colleagues reported in 2002 on the functional morphology of organotypic spleen cultures from rats of different ages exposed to the compound. Pliss and colleagues reported in 2001 on the effect of this dipeptide and epithalone on induction and growth of carcinogen-induced bladder neoplasms in rats.

The human work is thinner. Khavinson, Lezhava and Malinin reported in 2004 that short peptides of this class altered lymphocyte chromatin in elderly donors, which is a laboratory observation on cultured cells rather than a clinical outcome.

The proposed mechanism is not a classical receptor interaction. The developer-group hypothesis, set out in a 2021 review in Molecules, is that short peptides enter cells, reach the nucleus, bind DNA sequence-selectively and modulate gene expression. It comes from one lineage and lacks broad independent replication, and should be read that way rather than as established pharmacology. Further background sits in the research overview for this compound and the wider bioregulator research overview.

What has not been studied is worth stating plainly: there is no controlled human trial of the injected route for any endpoint, no independent non-Khavinson replication of the core claims, no pharmacokinetic data in humans or animals, and no solution-stability data for a device. As a small dipeptide it would be expected to be hydrolysed and cleared rapidly by peptidases, but that is inference rather than measurement.

Safety and Regulatory Position

Few adverse effects are reported in the published studies, and the studies are small, short and not designed to detect harm, so the absence of reported findings is not evidence of safety.

The compound holds no drug authorisation from any of those five regulators. It was developed and patented in Russia by the Khavinson group, and while some peptides from that group are registered as medicines or sold as parapharmaceuticals within the Russian Federation, the precise Russian registration status of this dipeptide is unverified here. In Western markets it is a research chemical.

No FDA-approved labelling exists, so there is no reference specification against which a supplier certificate can be compared. Its status on the 503A and 503B bulk drug substance lists was not established here and should be checked directly. Nothing under this name was found on the WADA Prohibited List, and the current version of that list was not read directly. Safety of chronic self-administration is unstudied.

How Does the Push Button on an Autoinjector Pen Work?

The device is a screw-driven dosing pen rather than a spring-loaded single-shot injector. Turning the dial winds a nut along a lead screw and sets how far the plunger rod will travel. Pressing the push button releases that travel, the rod advances the stopper inside the glass cartridge by exactly the wound distance, and the displaced volume leaves through the needle. The relationship between dial increments and delivered volume is mechanical and fixed, which is why the increment arithmetic on this page is reliable in a way that drawing from a vial with a syringe is not.

Two consequences follow for research use. First, the mechanism gives a repeatable volume but not a repeatable mass unless the concentration is known and stable, so the fill date still governs what a given increment actually contains. Second, the cartridge is a closed system entered through a fresh needle each time, which is a different contamination profile from a multi-entry vial. Neither point is about the peptide. Both are about the format.

What Can a Laser Tell You About a Solution Fill?

More than a mass spectrometer can, for the questions that matter in a preloaded device. Two established methods use a laser and answer different questions, and neither appears on a routine peptide certificate.

The first is light obscuration particle counting, the method behind the subvisible particle limits in the pharmacopoeias. Solution passes through a cell, a laser diode illuminates it, and each particle casts a shadow whose size is recorded. The output is a count of particles at or above ten and twenty-five micrometres per container. This is how a solution product is shown to be free of the particulate that a clear and colourless visual inspection cannot resolve, and a dipeptide fill in glass is exactly the case where it earns its keep, because the compound itself is invisible.

The second is dynamic light scattering. Here the laser illuminates the sample and the detector watches how quickly the scattered intensity fluctuates as particles move under Brownian motion. Faster fluctuation means smaller species. For a 275 dalton dipeptide the parent molecule is below the practical range of the technique, which is itself the useful result: any signal a laser scattering instrument does return from this solution is coming from aggregate, from excipient or from contamination, not from the peptide. A clean baseline is informative and an unexpected population is a flag.

Neither method identifies the compound. Both describe the physical state of the fill, which is the part of a solution product that changes fastest and is reported least. Where a supplier can provide a subvisible particle count for the lot, that document says something a purity percentage does not.

How Is the Gene Expression Claim Framed for a Dipeptide?

Khavinson’s model holds that short peptides of this size cross the membrane and the nuclear envelope, reach chromatin, and change gene expression by binding directly to specific sequences in promoter regions. For a two-residue molecule that model is harder to sustain than for the longer members of the family, because a dipeptide has very little surface with which to recognise anything specifically. The published support is largely computational docking plus gel-shift experiments in cell-free systems.

The cell-culture reports describe gene expression changes downstream: altered transcription of interleukin and interferon genes in lymphocyte preparations, and changed proliferation rates. Those are real measurements of gene expression outcomes. What they do not establish is that the dipeptide reached a nucleus intact, and no study in any species has traced the molecule from an injection site to chromatin. A dipeptide is also a substrate for common serum peptidases, so intact arrival is a strong assumption rather than an observation.

Read gene expression claims for this compound as descriptions of what changed in a dish, not as an established mechanism. That distinction survives the whole family, and it is sharpest here because the molecule is smallest.

Why Does Searching for This Product Return Writing Instruments?

Because the word pen belongs to two markets at once. A search for a peptide autoinjector by that name returns stationery results alongside the intended ones, so it is worth stating plainly what this device is and is not. This is a medical-format autoinjector holding a peptide solution in a glass cartridge. It is not a fountain pen, it takes no jumbo refill, and it has no touch pointer or stylus tip. Nothing sold under this product name has a nib or an ink converter.

The overlap runs deeper than the noun. Both categories use the vocabulary of cartridges, refills, barrels and clicks, and a fountain pen and an injection pen genuinely share the same basic engineering problem, which is moving a fixed volume of liquid out of a sealed reservoir in a controlled way. That is where the resemblance stops. One is a laboratory research device supplied to qualified researchers; the other is a writing instrument.

Published Literature

Five entries, each confirmed against a primary index before listing. All describe the compound; the device format has no published record of its own.

1. Khavinson VKh, Timofeeva NM, Malinin VV, et al. Effect of the dipeptide Vilon on activity of digestive enzyme in rats of various ages. Bull Exp Biol Med. 2001;131(6):583-585. DOI: 10.1023/A:1012319122696 PMID: 11586413
2. Pliss GB, Mel’nikov AS, Malinin VV, et al. Effect of vilon and epithalone on induction and growth of induced bladder neoplasms in rats. Vopr Onkol. 2001;47(5):601-607. PMID: 11785104
3. Kniaz’kin IV, Iuzhakov VV, Chalisova NI, et al. Functional morphology of organotypic culture of spleens from rats of various ages exposed to vilon. Adv Gerontol. 2002;9:110-115. PMID: 12096432
4. Khavinson VKh, Lezhava T, Malinin VV. Effects of short peptides on lymphocyte chromatin in senile subjects. Bull Exp Biol Med. 2004;137(1):78-81. DOI: 10.1023/B:BEBM.0000024393.40560.05 PMID: 15085253
5. Khavinson VKh, Popovich IG, Linkova NS, et al. Peptide regulation of gene expression: a systematic review. Molecules. 2021;26(22):7053. DOI: 10.3390/molecules26227053 PMID: 34834147

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