Dihexa (CAS 1401708-83-5, also listed as PNB-0408) is a synthetic oligopeptide derived from angiotensin IV, sold as a research chemical in powder, capsule, and transdermal forms. It draws buyer attention because of a striking lab claim — that it is far more potent than BDNF at building synaptic connections — but the evidence behind that claim has changed dramatically. This guide is built for sourcing decisions: what forms exist, what a Certificate of Analysis should show, and the honest evidence context a buyer needs before spending money.
Research-context information only. Dihexa is a research peptide. Protocols, doses, and reactions reported below come from published research and self-reported community sources. This article reports what has been documented, not what should be done. Consult a licensed physician for personal medical decisions.
This is not a ranked vendor list — for that, see our Best Dihexa Vendors comparison. This guide teaches how to evaluate any Dihexa listing yourself, with extra weight on the evidence context most competitor pages leave out.
Understanding Dihexa Pricing
Dihexa is sold strictly as a research chemical — not a supplement, not a compounded medicine, and not an FDA-approved drug. That distinction shapes everything about how it is priced and packaged. There is no pharmacopeial monograph, no standardized dose, and no regulatory floor on quality, so price tracks form factor, advertised purity, and how much active material is in the package.
Three forms dominate the market:
| Form | Typical packaging | What you're paying for | Notes |
|---|---|---|---|
| Lyophilized powder | ~500 mg vials/bottles | Raw research material by mass | Most flexible; requires the buyer to handle measurement and any solvent |
| Oral capsules | ~5 mg per capsule, 60-count | Pre-measured convenience | Higher cost per mg than bulk powder; the convenience is the premium |
| Transdermal (DMSO-based) | Pre-mixed solution | A solvent carrier + active | DMSO is a skin penetrant; community sources debate route, see evidence section below |
The pattern across research-chemical pricing is consistent: bulk powder carries the lowest cost per mg, while pre-measured capsules and pre-mixed transdermal solutions add a convenience premium. Because Dihexa has no established human dose, "cost per dose" math depends entirely on community-reported figures rather than any validated protocol — so per-mg comparisons of the raw material are the cleaner way to compare listings. For current vendor-specific pricing, see the Best Dihexa Vendors page.
How to Verify Dihexa Quality
With no regulatory oversight and no standardized product, the Certificate of Analysis (COA) is the only objective signal a buyer has. Dihexa is a small modified peptide (chemical name N-hexanoic-Tyr-Ile-(6)-aminohexanoic acid amide, formula C27H44N4O5, molecular weight ~504 Da). Synthesis impurities, incomplete reactions, and mislabeled material are real risks in the research-chemical market, and a COA is what distinguishes a tested batch from an unverified one.
What a COA Should Include
Identity confirmation
- Mass spectrometry confirming the correct molecular weight (~504 Da for Dihexa)
- Confirmation that the tested compound matches CAS 1401708-83-5 / PNB-0408
Purity testing
- HPLC purity — reputable listings claim ~98% or higher
- An HPLC chromatogram showing a single dominant peak, not a cluster of unresolved peaks
Contamination testing
- Residual solvent analysis (especially relevant given DMSO-based transdermal forms)
- Heavy metals screening where the supplier provides it
How to Verify a COA Is Legitimate
- Match the batch. The lot/batch number on the COA should match the number on the vial you receive — not just "a" COA for the product line.
- Check the date. A COA should be recent and tied to the production run you're buying, not a years-old generic certificate.
- Identify the lab. Independent third-party lab COAs carry more weight than in-house-only documents. A named lab you can look up is a better signal than an unsigned PDF.
- Read the chromatogram, not just the headline number. A "98%" claim with no attached HPLC trace is just a number. The trace should show one dominant peak.
- Confirm the compound identity. The COA should test for Dihexa specifically (correct mass, correct CAS), not a generic "peptide" assay.
Red Flags to Avoid
- No COA available, or a COA that won't load / is image-only with no lab name
- Batch numbers that don't match between COA and vial
- Purity claimed with no supporting HPLC chromatogram
- Marketing that presents the retracted "seven orders of magnitude more potent than BDNF" figure as settled fact (see the evidence section below)
- Human dosing instructions or therapeutic claims on the listing — a tell that the seller is ignoring RUO rules
- Vendor copy citing a "12.8-day half-life" as established — this figure appears only in vendor marketing, with no verifiable peer-reviewed source
A clean COA verifies that the powder is what the label says. It does not verify that Dihexa is safe in humans — no such data exists for this compound, which is the single most important thing for a buyer to understand.
