"BPC-157 arginate", "arginine salt" and "pentadeca arginate" (PDA) are sold as a more stable, better-absorbed version of BPC-157. The comparison is searched as a comparison — which one, and what is the difference — so this page answers it that way: what each form is, where the arginate form came from, what was actually measured, and what the difference means for the milligrams in a vial.
What the compound is, in beginner terms, is in Peptide Lexicon's pentadeca arginate entry. The BPC-157 dose record is on our BPC-157 dosage page and its harm record on our BPC-157 side effects page. Neither is restated. Nothing here is a recommendation.
Same peptide, different salt
BPC-157 is fifteen amino acids: Gly-Glu-Pro-Pro-Pro-Gly-Lys-Pro-Ala-Asp-Asp-Ala-Gly-Leu-Val. A freeze-dried peptide is almost never the bare molecule. It is a salt: the peptide's charged groups are paired with counter-ions left over from purification.
| Acetate form | Arginine ("arginate") form | |
|---|---|---|
| Peptide | BPC-157, 1,419.5 Da | BPC-157, 1,419.5 Da |
| Counter-ion | Acetic acid, 60.05 Da each, pairs with the peptide's two basic groups (the N-terminus and lysine) | L-arginine, 174.2 Da each, pairs with the peptide's acidic groups (one glutamate, two aspartates, the C-terminus) |
| Ratio in the patent | Not specified | 1, 2 or 3 arginines per peptide; 2 preferred |
| pH of a solution (patent) | 3.88 | 7.35 |
| What it changes | — | Stability, solution pH, mass per milligram |
| What it does not change | — | The amino acid sequence |
BPC-157 carries four acidic groups and two basic ones, so it is an acidic peptide. An acetate salt leaves its solution acidic; pairing it with a basic amino acid neutralises it. That single fact explains most of what the stability data below show.
Where the arginate form comes from
The earliest public record found of an arginine salt of BPC-157 is a patent: US 9,850,282, "Stable pentadecapeptide salts", filed by Diagen d.o.o. of Slovenia, inventor Rudolf Rucman, priority date 13 March 2013, granted 26 December 2017, with family members in Europe, Japan, China, Canada and elsewhere (Google Patents record, read 7 October 2026). It claims BPC-157 — which it calls bepecin — paired with one, two or three molecules of a basic amino acid (arginine, lysine, ornithine and others), and states that the salt with two arginines, "Arg-BPC", has "the most favourable properties."
The patent's stated problem is oral use. It says BPC-157 has been used "in a free form or in an acetate form or as a salt with bases such as sodium salt," and that all of these have "still not adequate stability in gastric juice, which particularly limits oral use."
"Pentadeca arginate" does not appear in the patent; it is a market name. A PubMed search for arginate or arginine salt with BPC-157 on 7 October 2026 returned no paper.
What the patent measured
All figures below are the patent holder's own HPLC measurements, from its Tables 1–6. They have not been independently replicated in any published paper found.
Solid powder, accelerated ageing (50 °C, 65% relative humidity), peptide content:
| Form | Day 0 | Day 30 | Day 90 |
|---|---|---|---|
| Acetate | 99.65% | 91.98% | 85.90% |
| Sodium salt | 99.20% | 96.46% | 97.14% |
| Di-arginine (Arg-BPC) | 99.46% | 99.20% | 99.07% |
In water at 50 °C: the acetate (pH 3.88) fell to 71.17% at 20 hours and 21.30% at 388 hours; the arginine salt (pH 7.35) was 99.01% at 388 hours; the sodium salt (pH 8.42) 96.74%. At 100 °C for one hour, the acetate fell to 56.80% and the arginine salt was unchanged.
In artificial gastric juice at 37 °C, percentage remaining:
| pH | Form | 0.5 h | 1 h | 2 h |
|---|---|---|---|---|
| 2.0 | Acetate | 21.4 | 8.2 | 2.46 |
| 2.0 | Arg-BPC | 30.2 | 13.5 | 6.0 |
| 3.0 | Acetate | 41.7 | 26.1 | 7.8 |
| 3.0 | Arg-BPC | 98.1 | 96.5 | 93.6 |
| 4.0 | Acetate | — | 89.7 | 81.3 |
| 4.0 | Arg-BPC | — | 99.9 | 99.5 |
Two readings of these tables matter more than the headline.
The sodium salt nearly matches the arginine salt. In the solid test it held 97.14% at 90 days against 99.07%; in warm water 96.74% against 99.01%. Both are neutral-to-basic salts. The big losers are the acetate and its acidic solution. Most of the stability gap looks like a pH effect that any basic counter-ion supplies, rather than something special about arginine.
At pH 2 the advantage largely disappears. An empty stomach is strongly acidic, commonly put at around pH 1 to 2. At pH 2.0 — the most acidic condition the patent tested — 13.5% of the arginine salt was left after an hour against 8.2% of the acetate. The dramatic difference is at pH 3 to 4, which is a fed or less acidic stomach. The patent's oral-stability case is real at the upper end of stomach acidity and thin at the lower end.
None of the tables measures absorption into the blood or any effect in a body. Stability in a test tube is a precondition for an oral peptide working, not evidence that it does; the record for swallowed peptides generally is on our oral peptides page, where approved ones reach about 1% bioavailability with special formulations.
What the salt does to the milligrams
This is the comparison sellers do not print. Because a salt includes its counter-ions, a weighed milligram of powder is not a milligram of peptide. Using PubChem's molecular weights (BPC-157 1,419.5; L-arginine 174.20; acetic acid 60.05) and the patent's ratios, here is the share of the mass that is peptide, before any water or impurities:
| Form | Mass per molecule of salt (Da) | Peptide share of mass | Peptide in a vial labelled 5 mg of salt |
|---|---|---|---|
| Free peptide | 1,419.5 | 100% | 5.0 mg |
| Acetate (2 acetates) | 1,539.6 | 92.2% | 4.6 mg |
| Mono-arginine (1:1) | 1,593.7 | 89.1% | 4.5 mg |
| Di-arginine, Arg-BPC (1:2, the patent's preferred) | 1,767.9 | 80.3% | 4.0 mg |
| Tri-arginine (1:3) | 1,942.1 | 73.1% | 3.7 mg |
This arithmetic is this site's own. It assumes the label weight is the salt; if a seller states the label weight as net peptide, the vial simply contains more powder. Real freeze-dried peptides also hold water, so measured net peptide content is usually lower than these figures. The practical point: at the same label weight and price, an arginate vial can contain about an eighth less BPC-157 than an acetate vial, and a buyer cannot tell which without a certificate that reports net peptide content — one of the checks set out on our peptide testing page and in our how to read a certificate of analysis guide.
What is not established
- That the arginate form does anything different from the acetate in an animal or a person. No comparative study of effect exists.
- That either form, swallowed, reaches the blood in a meaningful amount. Not measured.
- That products sold as "pentadeca arginate" are the patent's di-arginine salt, or BPC-157 at all. No public analytical record links a product to the structure.
- That the patent's stability figures replicate outside the patent holder's laboratory.
- Whether the arginine dose itself — under 1 mg per 5 mg vial — matters. At those amounts it is a small fraction of dietary arginine.
Sources and dates
- US Patent 9,850,282 B2, "Stable pentadecapeptide salts, a process for preparation thereof, a use thereof in the manufacture of pharmaceutical preparations and a use thereof in therapy." Diagen d.o.o.; inventor Rudolf Rucman; priority 2013-03-13 (SI 201300055); granted 2017-12-26. Google Patents, full text and Tables 1–6 read 2026-10-07. Kind of source: patent (manufacturer's own data).
- PubChem: BPC-157 CID 9941957 (1,419.5 g/mol, C62H98N16O22); L-arginine CID 6322 (174.20); acetic acid CID 176 (60.05). Read 2026-10-07.
- PubMed: BPC-157 with arginate or arginine salt, queried 2026-10-07 — no paper. ClinicalTrials.gov: pentadeca arginate — no registration, queried 2026-10-07.