Peptide Schedule
HGH (Somatropin)31 residues (approx.)FPTIPLSRLFDNAMLRAHRLHQLAFDTYQEFEach bubble = one amino acid. Size = residue mass. Color = chemical class.Uses closest standard amino acids for non-standard residues.HGH (Somatropin)
Benefits
About HGH (Somatropin)
Somatropin is recombinant human growth hormone — a 191-amino-acid protein identical to what your pituitary gland produces naturally. It's been FDA-approved since 1985 and is sold under brand names like Genotropin (Pfizer), Humatrope (Lilly), Norditropin (Novo Nordisk), and Omnitrope (Sandoz). Unlike secretagogues that coax your pituitary into releasing GH, somatropin is the hormone itself, delivering predictable, dose-dependent elevations in serum GH and IGF-1. The landmark Rudman et al. study (NEJM, 1990) showed that six months of GH administration in men over 60 increased lean body mass by 8.8% and decreased adipose tissue by 14.4%. That paper ignited decades of research into GH's effects on body composition, bone density, and quality of life. More recent data from the KIMS database — tracking 15,809 GH-treated adults — confirmed a favorable long-term safety profile with neutral effects on lipids and glucose when dosed appropriately. Clinically, somatropin treats pediatric and adult growth hormone deficiency, Turner syndrome, chronic kidney disease in children, Prader-Willi syndrome, and HIV-associated wasting. Off-label, it's used at lower doses (1-2 IU/day) for anti-aging, improved sleep architecture, skin elasticity, and body recomposition. At moderate doses (2-4 IU), athletes and patients recovering from injuries report faster healing and better recovery. Higher doses (4-8 IU) enter bodybuilding territory and carry greater side-effect risk. Somatropin's pharmacokinetics are straightforward: subcutaneous injection gives ~80% bioavailability, peak serum levels at 3-5 hours, and a terminal half-life of about 2-3 hours. The biological effects, mediated through IGF-1, last far longer — roughly 20-24 hours — which is why once-daily dosing works well.
Who Should Consider HGH (Somatropin)
- Adults with diagnosed growth hormone deficiency (AGHD)
- Children with GHD, Turner syndrome, or idiopathic short stature
- HIV patients with wasting or lipodystrophy
- Anti-aging patients seeking improved body composition and skin quality
- Athletes and bodybuilders (off-label, higher doses)
How HGH (Somatropin) Works
Somatropin binds to the growth hormone receptor (GHR), a transmembrane receptor that exists as a preformed dimer on cell surfaces. When GH binds, it triggers a conformational change that activates Janus Kinase 2 (JAK2), a tyrosine kinase physically associated with the receptor's intracellular domain. JAK2 then phosphorylates tyrosine residues on the GHR itself, creating docking sites for STAT proteins — primarily STAT5b. Once recruited, STAT5b gets phosphorylated by JAK2, dimerizes, and translocates to the nucleus where it drives transcription of target genes. The most important downstream target is IGF-1 (insulin-like growth factor 1), produced mainly by the liver. IGF-1 mediates most of GH's anabolic effects: protein synthesis, cell proliferation, and inhibition of apoptosis. GH also activates the MAPK/ERK pathway (promoting cell growth) and the PI3K/Akt pathway (regulating glucose metabolism and cell survival). The direct lipolytic action of GH — breaking down stored triglycerides — occurs through a separate, non-IGF-1-mediated mechanism involving hormone-sensitive lipase activation in adipocytes.
What to Expect
Better sleep quality is usually the first noticeable effect. Mild water retention and joint stiffness may appear as the body adjusts.
Skin starts looking fuller and more hydrated. Energy levels improve. Recovery from workouts is noticeably faster.
Measurable fat loss begins, especially visceral fat. Lean mass increases become apparent. Nails and hair grow faster.
Significant body recomposition. Rudman's study showed 8.8% lean mass increase and 14.4% fat reduction at 6 months. Bone density improvements begin.
Full benefits realized. Bone mineral density measurably improved on DEXA. Lipid profile improvements stabilize. Skin elasticity at peak improvement.
Dosing Protocol
| Level | Dose / Injection | Frequency |
|---|---|---|
| Beginner | 1 IU | Daily |
| Moderate | 3 IU | Daily |
| Aggressive | 6 IU | Daily |
Note: FDA-approved recombinant human growth hormone. Brands include Genotropin, Humatrope, Norditropin, Omnitrope. Dosed in IU — 1 IU ≈ 0.33mg. Pre-filled pens need no reconstitution. Lyophilized vials reconstitute with 1-2mL provided diluent. Inject SC, rotate sites. Monitor IGF-1 every 3-6 months.
How to Inject HGH (Somatropin)
Inject subcutaneously into the abdomen, thigh, or upper arm. Rotate injection sites to prevent lipodystrophy. Best administered in the morning to mimic natural circadian GH release, or split into AM and pre-bed doses at higher protocols. Inject on an empty stomach — food (especially carbs) blunts GH action. Pre-filled pens (Norditropin, Genotropin) require no reconstitution. For lyophilized vials, reconstitute gently with provided diluent or bacteriostatic water — never shake.
Cycling Protocol
For anti-aging doses (1-2 IU), many practitioners run continuously with periodic IGF-1 monitoring rather than cycling. At higher doses (4+ IU), 6 months on / 1 month off helps maintain insulin sensitivity. Some protocols use 5 days on, 2 days off weekly to reduce cost and manage sides.
Pharmacokinetics
Source: Norditropin FDA label Section 12.3 — SC t½ 2-3 hours (mean ~2.5h); Genotropin label reports 3.0h in GHD adults
Loading the interactive decay curve.
Side Effects
The most common side effects are dose-dependent and typically manageable. Peripheral edema (swelling in hands and feet) affects up to 45% of patients at higher doses and usually resolves within weeks. Joint pain and muscle stiffness occur in roughly 20% of users, especially early on. Carpal tunnel syndrome shows up in 1-10% of cases — it's caused by fluid retention compressing the median nerve and almost always reverses with dose reduction. Insulin resistance is the side effect that demands the most attention. Somatropin antagonizes insulin's action on glucose uptake, which can unmask pre-diabetes or worsen existing diabetes. Fasting glucose and HbA1c should be monitored every 3-6 months. Gynecomastia is rare but possible. At high doses (>4 IU/day), some users report jaw growth and increased shoe size over years of use — signs of acromegaly-like effects. There's also ongoing debate about cancer risk, though the KIMS database of 15,809 patients found no increased cancer incidence with appropriate dosing.
Contraindications
- Active malignancy — GH and IGF-1 can promote tumor growth
- Active proliferative or severe non-proliferative diabetic retinopathy
- Acute critical illness (post-surgery, trauma, respiratory failure)
- Prader-Willi syndrome with severe obesity or respiratory impairment (pediatric)
- Closed epiphyses in pediatric patients (for growth indication)
- Pregnancy or breastfeeding (Category B/C depending on indication — insufficient human data)
- Known hypersensitivity to somatropin or excipients
Drug Interactions
- Insulin and oral hypoglycemics — GH reduces insulin sensitivity; diabetes meds may need dose increases
- Glucocorticoids — may attenuate GH's growth-promoting effects; GH may reduce cortisol conversion via 11β-HSD1
- Oral estrogens — reduce IGF-1 response to GH; women on oral estrogen may need higher GH doses
- CYP450 substrates (theophylline, cyclosporine, warfarin) — GH may alter clearance; monitor drug levels
- Thyroid hormones — GH can unmask central hypothyroidism; monitor TSH and free T4
Storage & Stability
Molecular Profile
Related Peptides
References
- Effects of Human Growth Hormone in Men over 60 Years Old (Rudman et al., NEJM 1990)PubMed 2355952
- Long-term Safety of Growth Hormone in Adults — Overview of 15,809 GH-Treated Patients (KIMS)PubMed 35368070
- Long-term Efficacy and Safety of Somatropin for Adult GHDPubMed 15871547
- Norditropin (somatropin) FDA Prescribing InformationFDA Label
- Genotropin (somatropin) FDA Prescribing InformationFDA Label