BPC-157 Stability: Why It Is Called the Stable Gastric Pentadecapeptide

LynxLab · 24 October 2026 · 8 min read

Why BPC-157 is described as stable in gastric juice, what the oral and injected animal studies found, its half-life, and how the freeze-dried peptide is stored.

Photo: CDC, Unsplash

Almost every paper from the Zagreb group calls it "stable gastric pentadecapeptide BPC 157", and each word is a claim. Pentadecapeptide means 15 amino acids. Gastric means it was found in stomach juice.

Stable is the interesting one, because most peptides fall apart in acid within minutes, and it is the reason bpc-157 is discussed as an oral compound as well as an injected one. This post looks at what the stability claim rests on, what the pharmacokinetic data say, and how the peptide behaves in a vial.

What the name says about the molecule

The sequence is Gly-Glu-Pro-Pro-Pro-Gly-Lys-Pro-Ala-Asp-Asp-Ala-Gly-Leu-Val, written GEPPPGKPADDAGLV, with a molecular weight of 1419 (Staresinic et al., J Orthop Res 2003). It was described in 1993 as a 15 amino acid fragment of a much larger protein, around 40,000 molecular weight, that Predrag Sikiric's group isolated from human gastric juice (Sikiric et al., J Physiol Paris 1993).

The parent protein has never been fully characterised in the open literature. A 2025 review from a Polish group noted that the sequence shows no homology with known intestinal peptides (Józwiak et al., Pharmaceuticals 2025), and Jong-Hwei Su Pang of Chang Gung University told Undark it may be produced by stomach microbes, since the sequence does not appear in the human genome (Talpos, STAT 2026).

What is not in dispute is that the 15-mer is small, contains four prolines and has no cysteine, so there are no disulphide bridges to break. That is the molecule a lab receives when it orders bpc 157 as a freeze-dried powder.

The gastric juice claim and where it comes from

The claim is specific. The Zagreb group states that, unlike growth factor peptides, which need a carrier and "are rapidly degraded in human gastric juice", BPC 157 is "native and resistant to human gastric juice" for a period exceeding one day (Seiwerth et al., Frontiers in Pharmacology 2021).

That is the origin of the word "stable" in the name. It is also, as far as we can find, a statement that has only ever been published by the group that discovered the peptide, with the supporting references being its own earlier papers.

The Polish review accepted the point, describing the structure as rendering the peptide "stable in water and gastric juice", while noting that low stability is a common problem for peptide drugs in general. We could not find an independent gastric juice incubation using modern mass spectrometry.

Oral versus injection in the animal studies

The Zagreb group has used oral and injected routes side by side since the start. The 1993 paper reported effects after intraperitoneal, intragastric and local application, at microgram and nanogram per kilogram doses.

The clearest comparison is the 2010 ligament study. Cerovecki and colleagues transected the rat medial collateral ligament and treated animals either by intraperitoneal injection at 10 micrograms or 10 nanograms per kilogram, by a thin layer of cream at the injury site, or by adding 0.16 micrograms per millilitre to the drinking water, at roughly 12 millilitres a day per rat (Cerovecki et al., J Orthop Res 2010). All three routes were reported to improve healing over 90 days.

The Achilles tendon papers used injection only, starting 30 minutes after surgery and once daily after that. So the oral evidence rests mainly on drinking water studies in rats, while the best known tendon results are injected.

That matters for anyone planning work with bpc-157 for research. The two routes are not interchangeable in the literature, and no study has compared blood levels after each in the same animals.

What the pharmacokinetic study found

The only published pharmacokinetic study comes from a group at Air Force Medical University in Xi'an, not from Zagreb. He and colleagues gave BPC 157 intravenously and intramuscularly to rats and beagle dogs and found an elimination half-life of under 30 minutes by both routes, with linear kinetics across the doses tested (He et al., Frontiers in Pharmacology 2022).

Absolute bioavailability after intramuscular injection was roughly 14 to 19 percent in rats and 45 to 51 percent in dogs. Using tritium-labelled peptide, the authors showed it was broken quickly into smaller fragments and then single amino acids, excreted in urine and bile.

Two things follow. The peptide is cleared fast even when injected, so "stable" refers to acid, not to time in the body. And the study did not test the oral route at all, so there is still no published measurement of how much BPC 157 reaches the blood after swallowing.

The one human oral study on record, a 2015 phase 1 trial of 1mg tablets registered as NCT02637284 and planned for 42 volunteers in Tijuana, has never posted results (NCT02637284, ClinicalTrials.gov). Anyone who wants to buy bpc-157 to study oral stability is therefore working from rat data and one unpublished trial.

Stability in the vial: freeze-dried versus in solution

Synthetic BPC-157 is supplied as a freeze-dried powder, usually as a trifluoroacetate or acetate salt. Lyophilised peptide is the stable form. Thermo Fisher's handling sheet for standard synthetic peptides advises storing them at minus 20 degrees Celsius on receipt, at which they "may remain stable for several years" (Thermo Fisher, handling and storage instructions).

The same sheet is blunt about solutions: "Peptide solutions should be used up immediately as they are unstable (the lower the concentration, the more unstable)." It adds that many peptides are light-sensitive and that repeated freezing and thawing must be avoided.

The freeze-thaw point has been measured. A 2016 Clinical Chemistry paper on peptide handling for mass spectrometry found that signal variability was highest after ten freeze-thaw cycles and lowest for samples stored frozen and thawed immediately before analysis (Hoofnagle et al., Clinical Chemistry 2016).

In laboratory practice that means a sealed vial kept cold and dark, single-use aliquots rather than repeated draws from one solution, and a written reconstitution date. A bpc-157 20mg vial that has sat on a bench in daylight is not the same reagent it was on arrival.

Reconstitution and bacteriostatic water

Freeze-dried peptide has to be dissolved before it can go into an assay. The usual diluent for multi-draw laboratory work is bacteriostatic water, which the US label describes as sterile water for injection containing 0.9 percent (9 mg/mL) benzyl alcohol "added as a bacteriostatic preservative", supplied in a multiple-dose container "from which repeated withdrawals may be made" (DailyMed, Bacteriostatic Water for Injection label).

The benzyl alcohol stops bacteria growing in an opened vial. It does nothing to slow chemical breakdown of the peptide itself, which is why the label still says to "mix thoroughly and use promptly" and not to store reconstituted drugs "unless otherwise directed by the manufacturer". The label gives a pH of 5.7, mildly acidic.

None of that is dosing information. It is the chemistry that decides whether what is in a vial a week after mixing is still research-grade bpc-157 or a mixture of fragments, and it is why a lab report describes the sealed powder, not the solution.

What stability does and does not tell you

"Stable gastric pentadecapeptide" is an accurate description of three properties: 15 residues, gastric origin, and reported resistance to acid. It is not evidence that the peptide works by mouth in people, that it survives long in the bloodstream, or that a given vial is pure.

The first of those gaps is covered in our post on what the BPC-157 research actually shows. The third is why regulators raise "peptide-related impurities" every time the compound comes up, as set out in BPC-157 legal status in the UK, WADA and the FDA.

LynxLab stocks BPC-157 for research use in 5mg, 10mg and 20mg vials from £16.95, tested to 99% purity with the certificate of analysis on the product page.

Frequently asked questions

Why is BPC-157 called the stable gastric pentadecapeptide?

Because it is a 15 amino acid peptide (a pentadecapeptide) first isolated from human gastric juice, and because the Zagreb group that discovered it reports that it survives in human gastric juice for more than a day, unlike most peptides. The stability claim comes from that group's own work.

Does BPC-157 work orally?

In rats, the Zagreb group reported ligament healing when the peptide was added to drinking water (Cerovecki et al., 2010). No published study has measured oral absorption in any species, and the one human oral trial, registered in 2015, never reported results.

What is the half-life of BPC-157?

Under 30 minutes after intravenous or intramuscular injection in rats and dogs, according to the only published pharmacokinetic study (He et al., 2022). The peptide is broken down into fragments and amino acids and cleared in urine and bile.

How long does freeze-dried BPC-157 last?

Peptide suppliers' handling guidance is that lyophilised peptides stored at minus 20 degrees Celsius may remain stable for several years, while solutions are unstable and should be used promptly. Light and repeated freeze-thaw cycles both shorten that, which is worth knowing before ordering bpc-157 uk stock in a larger size than a project needs.

Sources

Research use only

BPC-157 from LynxLab

5mg, 10mg, 20mg vials from £16.95. ≥99% purity, lab report on the page. Same-day dispatch, UK stock.

Buy BPC-157

More on BPC-157

All articles · BPC-157 product page · Lab reports