What's on the label is the measured result — net peptide mass, not gross powder weight, plus RP-HPLC purity, on a lot-numbered COA for every batch.
Net peptide mass and RP-HPLC purity — a lot-numbered COA for every batch.
Net peptide mass + HPLC purity, per lot.
PCAC will review 7 peptides for the 503A bulks list, BPC-157, KPV, TB-500, MOTS-c, Emideltide, Semax, Epitalon. Read our briefing →
PCAC will review 7 peptides for the 503A bulks list. Read →
FDA PCAC reviews 7 peptides in July. Read →
Recombinant human growth hormone · 191-amino-acid somatropin
PeptideXpo primary owner
PeptideXpo owns the broad sourcing intent for HGH because buyers usually compare supplier credibility, fill availability, documentation readiness, and adjacent catalog coverage before narrowing into a specialist evidence request. The page should remain a sourcing hub rather than a research-standard or pharmacy-only monograph.
Overview
HGH — somatropin — is recombinant human growth hormone: a 191-amino-acid single-chain polypeptide with two intramolecular disulfide bonds, identical in primary sequence to the ~22 kDa growth hormone secreted by the human anterior pituitary. The "191aa" designation is the key identity marker: it distinguishes natural-sequence somatropin from the older 192-amino-acid "somatrem" (met-hGH), which carries an extra N-terminal methionine left over from first-generation E. coli expression. All current recombinant hGH, including the material PeptideXpo documents, is the 191aa form. As an active ingredient, somatropin is the basis of numerous approved finished growth-hormone drugs (Genotropin, Norditropin, Humatrope, Omnitrope, Saizen, and others). PeptideXpo supplies lyophilized somatropin (191aa) at ≥99.0% HPLC purity with batch-specific COA: peak-integration HPLC, intact-mass confirmation against the ~22,124 Da theoretical, and — because growth hormone is dosed by bioactivity rather than by mass alone — the per-vial potency in International Units. The WHO somatropin standard is ~3 IU per milligram, so a 10 IU vial corresponds to ≈3.3 mg of protein; standard fills span 6 IU to 40 IU per vial, matching the strengths on our HGH COA library. Host-cell-protein and bacterial-endotoxin (LAL, USP <85>) testing plus peptide-map / LC-MS/MS identity are available as add-ons and are recommended for any in vivo or compounding-track qualification — recombinant hGH carries materially more regulatory weight than the research-peptide catalog, so documentation depth matters.
Who buys this, and why
GH-axis peptides ship to two main buyer types: compounding pharmacies dispensing under physician supervision, and research labs studying somatotropic-axis pharmacology. Pharmacies typically want sterile-filled vials with the full release packet (sterility, endotoxin, CCI); labs typically want bulk lyophilized powder with sequence verification. Blends (the CJC-1295 / Ipamorelin combination is the canonical example) are usually co-lyophilized rather than solution-mixed for potency stability.
Primary buyer fit: 503A / 503B compounding pharmacies, academic and contract research laboratories, and regional distributors and re-sellers.
Specifications
Documentation available on request
Regulatory note
Somatropin is the active ingredient of multiple approved prescription growth-hormone products and is a tightly controlled recombinant hormone — substantially more regulated than research peptides. In the United States, distribution of growth hormone for non-approved uses is restricted under 21 U.S.C. §333(e), and many jurisdictions treat recombinant hGH as prescription-only or as a controlled substance. PeptideXpo supplies bulk somatropin only for research and for licensed compounding where local regulations expressly permit, under the receiving party's quality system. Buyers are solely responsible for confirming their legal eligibility to purchase, import, and use recombinant hGH in their market before ordering.
Frequently asked questions
"191aa" means the somatropin is the full natural-sequence human growth hormone — 191 amino acids, identical to the hormone the pituitary secretes. "192aa" refers to somatrem (met-hGH), an older recombinant form with one extra N-terminal methionine that remained when first-generation E. coli systems expressed the protein without removing the start methionine. The extra residue made 192aa material more immunogenic in early clinical use, which is why essentially all modern recombinant hGH is the 191aa natural-sequence form. If a COA does not state 191aa explicitly, ask — it is a basic identity attribute for this molecule.
Growth hormone is standardized by bioactivity, so it is labeled in International Units. The current WHO somatropin reference assigns ~3 IU per milligram of protein — the conversion most of the field uses. That makes a 10 IU vial ≈ 3.3 mg, a 15 IU vial ≈ 5 mg, and a 40 IU vial ≈ 13.3 mg. Because the IU figure reflects assayed potency rather than weighed mass alone, a credible HGH COA should report the per-vial IU alongside the HPLC purity and intact-mass identity.
A batch-specific somatropin COA should carry: (1) RP-HPLC with peak integration showing main-peak purity (our release target is ≥99.0%), (2) intact-mass confirmation (ESI or MALDI) against the ~22,124 Da theoretical, (3) the per-vial potency in IU, and (4) appearance / water content. For in vivo research or any compounding-track qualification, add host-cell-protein (HCP) ELISA, bacterial endotoxin (LAL, USP <85>), and a peptide map or LC-MS/MS identity — recombinant proteins expressed in microbial or mammalian hosts need HCP and endotoxin control that small synthetic peptides do not. PeptideXpo can extend the analytical scope per batch; specify destination market and intended use at quote stage.
They sit at opposite ends of the growth-hormone axis. Recombinant HGH (somatropin) is the hormone itself — exogenous growth hormone introduced directly. Secretagogues contain no growth hormone; they stimulate the body's own somatotrophs to release endogenous GH: Sermorelin, CJC-1295, and Tesamorelin are GHRH-receptor agonists (the "release" signal), while Ipamorelin and the GHRPs are GHSR / ghrelin-receptor agonists (the "amplify" signal) — which is why GHRH + GHRP combinations such as CJC-1295 + Ipamorelin are studied together. The practical contrast: exogenous HGH delivers a defined dose but bypasses physiological feedback, whereas secretagogue-driven release is pulsatile and self-limiting. The related SKUs on this page point to those secretagogues for the comparison.
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