Somatex GH pen

Regulatory framework + WADA

Somatex PEN 60 IU is a chemical reagent intended exclusively for laboratory research (Research Use Only) in pen format. The active substance — somatropin (recombinant human growth hormone, rhGH) — is also present on the market as a registered medicinal product under the trade names of numerous pharmaceutical manufacturers. These two instances are two distinct regulatory frameworks — the RUO reagent is not a medicine, is not intended for human use, and is not subject to pharmaceutical regulation. Somatropin is on the WADA Prohibited List (category S2 — peptide hormones and growth factors) — athletes subject to anti-doping control may not use it at any point during the year.

Growth hormone is one of the best-characterized signaling proteins in endocrinology — from its isolation in the 1950s to recombinant production by genetic engineering, which replaced extraction from human cadaver pituitaries. Somatropin is a synthetic, recombinant version of human growth hormone with a sequence identical to the endogenous protein. In the research reagent market it is available in pen format — a pre-dissolved cartridge enabling precise withdrawal of solution in laboratory protocols studying the GH-IGF1 axis. Somatex PEN belongs to the 191 amino acid sequence category — authentic, full-length somatropin.

This description is educational in nature and describes the scientific literature on somatropin in a research context. The Somatex PEN product functions exclusively as a chemical reagent for laboratory research (Research Use Only). It is not a medicinal product, dietary supplement, or food product.

What is somatropin — structure and class

Somatropin is a recombinant human growth hormone (rhGH) — a polypeptide of 191 amino acids with a molecular weight of approximately 22,124 Da (22 kDa), containing two intramolecular disulfide bridges. The somatropin sequence is identical to the endogenous growth hormone produced by the somatotroph cells of the anterior pituitary lobe.

Recombinant production of somatropin — in bacterial cells (Escherichia coli) or mammalian cells carrying an introduced human GH gene — replaced the historical method of obtaining the hormone from human cadaver pituitaries, which carried a risk of transmitting prion diseases. Modern somatropin is a product of genetic engineering with high purity and reproducibility.

Chemical characteristics

Mechanism of action in research

Somatropin binds to the growth hormone receptor (GHR) — a membrane receptor from the cytokine receptor family. Binding of one hormone molecule to two receptor subunits leads to receptor dimerization and activation of an intracellular signaling cascade:

• JAK2/STAT5 pathway — the receptor-associated kinase JAK2 phosphorylates STAT5 transcription factors, which translocate to the cell nucleus and modulate the expression of GH-response genes
• GH-IGF1 axis — one of the main effects of GHR activation in the liver is stimulation of the production of insulin-like growth factor 1 (IGF-1), which mediates many of the peripheral effects of growth hormone
• Metabolic pathways — in research models, somatropin modulates lipid metabolism, carbohydrate balance, and protein turnover

In the scientific literature, somatropin and the GH-IGF1 axis have been the subject of research for decades — from growth physiology, through energy metabolism, to tissue regeneration processes in preclinical models. The GHR receptor mechanism and JAK2/STAT5 signaling are among the well-documented pathways of molecular endocrinology.

Applications in scientific research

As a research reagent, somatropin is used in laboratory studies of:

• The pharmacology of the growth hormone receptor (GHR) and JAK2/STAT5 signaling
• The GH-IGF1 axis in cellular and animal models
• Lipid metabolism, carbohydrate metabolism, and protein turnover
• Tissue regeneration processes in preclinical models
• Comparative analyses with GH-axis peptides — GH secretagogues (such as MK-677 / ibutamoren) and growth hormone fragments (HGH Fragment 176-191). The distinction between approaches to the GH axis is discussed in the MK-677 vs HGH Fragment 176-191 analysis

One Peptides quality specification

Each batch of Somatex PEN undergoes a five-stage analytical control procedure:

• HPLC ≥98% — chromatographic purity confirmed by high-performance liquid chromatography
• MS confirmation — structural identity confirmed by mass spectrometry through comparison of measured mass with theoretical mass (~22 kDa)
• COA per batch — a public certificate of analysis for each batch (see quality testing and certificates)
• Cold chain 2–8°C — cold chain from synthesis to delivery; somatropin is a temperature-sensitive protein
• Batch traceability — batch number recorded on the pen, invoice, and COA

Working with a pre-dissolved pen in a laboratory protocol

• The pen contains somatropin as a pre-dissolved solution in a cartridge — with no need for reconstitution before use
• Withdrawal of solution under laboratory conditions with microliter precision
• Storage: under cold-chain conditions at 2–8°C; somatropin is sensitive to heat, light, and agitation (risk of protein denaturation and foam formation). Broader context in the storing peptides — temperature, light, and stability guide
• The solution must not be frozen or vigorously shaken
• The stability of the solution in the pen after first opening depends on storage conditions — typically up to several weeks at 2–8°C
• The RUO pen on the market is intended for laboratory research, not for injection in humans

Regulatory status and WADA

• Somatex PEN (this product): an RUO research reagent in the EU, labeled “For research use only. Not for human use”
• Somatropin as a medicine: registered by the EMA and FDA as a medicinal product for specific endocrinological indications, available by prescription only under the trade names of numerous manufacturers. This is a regulatory framework separate from the RUO reagent.
• WADA: somatropin (growth hormone) is on the Prohibited List in category S2 — the prohibition applies year-round, across all disciplines subject to anti-doping control.

Frequently asked questions

How does Somatex PEN differ from a registered somatropin medicine?

The active substance is the same — recombinant somatropin with a sequence identical to human growth hormone. What differs is the regulatory framework: a registered medicine is a medicinal product authorized by the EMA/FDA, available by prescription, with full registration documentation and medical oversight. Somatex PEN is a Research Use Only chemical reagent — a substance for laboratory research, with no intended use in humans.

What does 60 IU correspond to in milligrams?

According to the World Health Organization conversion factor, 1 mg of somatropin corresponds to approximately 3 international units (IU). A 60 IU pen therefore contains about 20 mg of recombinant somatropin.

How should somatropin be stored under laboratory conditions?

Somatropin is a protein sensitive to temperature, light, and agitation. It requires storage in a cold chain at 2–8°C, away from light. The solution must not be frozen or vigorously shaken — shaking causes foam formation and protein denaturation. The pen should be kept upright in the refrigerator.

Is somatropin on the WADA list?

Yes. Somatropin (growth hormone) is on the WADA Prohibited List in category S2 (peptide hormones and growth factors). The prohibition applies year-round.

How does the pen differ from the vial form of somatropin?

The pen contains somatropin as a pre-dissolved solution, ready for withdrawal without a reconstitution step. The vial form (lyophilizate) — such as the Medsomatrope 100 IU + BAC Water set — requires reconstitution in bacteriostatic water before use, but provides full control over the concentration of the working solution. The choice of form depends on the research protocol.

References

1. Brooks AJ, Waters MJ (2010). The growth hormone receptor: mechanism of activation and clinical implications
2. Ranke MB, Wit JM (2018). Growth hormone — past, present and future
3. Møller N, Jørgensen JOL (2009). Effects of growth hormone on glucose, lipid, and protein metabolism in human subjects

Chemical reagent intended exclusively for laboratory research (Research Use Only). Somatex PEN in the One Peptides catalog is not a medicinal product, dietary supplement, or food product. It is not intended for administration to humans or animals outside a controlled experimental environment. Somatropin is on the WADA Prohibited List (S2). The information in this description is educational and scientific in nature and concerns results reported in the literature — it does not constitute medical advice or a suggestion of use in humans.