HGH 191AA (Somatropin)
Also called Human growth hormone; somatropin; Genotropin and other brands
"191AA" just describes the 191-amino-acid human growth hormone molecule; somatropin is the recombinant prescription version. Replacement has evidence in diagnosed deficiency, not for general anti-aging or fat loss.
Overview
What it is
A polypeptide hormone made by the pituitary. Recombinant somatropin matches the natural sequence. The amino-acid count is not a quality or strength label.
How it works
Growth hormone acts on tissues directly and raises IGF-1. It increases fat breakdown and reduces insulin sensitivity.
What the research shows
The Endocrine Society describes improvements in body composition, exercise capacity, bone and quality of life in adults with confirmed growth hormone deficiency. A systematic review of healthy older adults found limited benefit and more side effects. In recreational athletes, body-composition changes did not translate into broad performance gains.
Studied for
- Adult growth hormone deficiencyapproved
- Pediatric growth disordersapproved
- Healthy aginglimited benefit, more harm
- Athletic performancelimited
Safety and regulatory status
Safety and side effects
Side effects include fluid retention, swelling, joint and muscle pain, carpal tunnel symptoms and reduced insulin sensitivity. Labels warn about glucose problems and raised pressure in the skull; severe headache or vision changes need prompt care. Active cancer is a contraindication.
Regulatory status
Specific somatropin products are FDA approved for defined uses. "HGH 191AA" research vials are not. Prohibited at all times by WADA.
Mixing and dosing reference
Reference information only. Read before using this section.
HGH 191AA (10IU Vial) Dosage Protocol
- Vial
- 10 IU / 3.33 mg HGH 191AA
- Add diluent
- 3 mL
- Concentration
- 1.11 mg/mL
- 1 unit (U-100)
- 11.1 mcg in 0.01 mL
- Route
- Subcutaneous
- How often
- Once per day (subcutaneous), preferably at bedtime.
- Typical range
- Conservative: 150–500 mcg daily; Advanced: 1000–2000 mcg daily.
- Cycle length
- 8–12 weeks standard; optional extension to 16 weeks with appropriate monitoring.
Standard / Gradual Titration
| Week | Daily Dose (mcg) | Units (per injection) (mL) |
|---|---|---|
| Week 1 | 200 mcg | 18 units (0.18 mL) |
| Week 2 | 300 mcg | 27 units (0.27 mL) |
| Week 3 | 400 mcg | 36 units (0.36 mL) |
| Week 4 | 500 mcg | 45 units (0.45 mL) |
| Week 5 | 600 mcg | 54 units (0.54 mL) |
| Week 6 | 700 mcg | 63 units (0.63 mL) |
| Week 7 | 800 mcg | 72 units (0.72 mL) |
| Week 8 | 900 mcg | 81 units (0.81 mL) |
Extended 12-Week Protocol (Optional)
| Week | Daily Dose (mcg) | Units (per injection) (mL) |
|---|---|---|
| Week 9 | 1000 mcg | 90 units (0.90 mL) |
| Week 10 | 1100 mcg | 99 units (0.99 mL) |
| Week 11 | 1200 mcg | 108 units (1.08 mL) |
| Week 12 | 1300 mcg | 117 units (1.17 mL) |
How to mix
- Draw 3.0 mL bacteriostatic water with a sterile syringe.
- Inject slowly down the vial wall; avoid foaming.
- Gently swirl/roll until dissolved (do not shake vigorously to preserve protein structure).
- Label and refrigerate at 2–8 °C (35.6–46.4 °F), protected from light.
Dosing details
- Start: 200 mcg daily; increase by ~100 mcg each week as tolerated.
- Conservative Target: 400–900 mcg daily by Weeks 4–8.
- Advanced Target: 1000–1300 mcg daily by Weeks 9–12 (performance/metabolic research protocols).
- Frequency: Once per day (subcutaneous), preferably at bedtime.
- Cycle Length: 8–12 weeks standard; optional extension to 16 weeks with appropriate monitoring.
- Timing: Evening or bedtime administration preferred; rotate injection sites systematically.
Storage
- Lyophilized: Store at −20 °C (−4 °F) in dry, dark conditions; minimize moisture exposure.
- Reconstituted: Refrigerate at 2–8 °C (35.6–46.4 °F); stable for several weeks when stored properly.
- Allow vials to reach room temperature before opening to reduce condensation uptake.
- Critical: Avoid freeze–thaw cycles of reconstituted peptide, as freezing can denature the protein.
Administration technique
- Subcutaneous injection guidance from clinical best-practice resources.
- Clean the vial stopper and injection site with alcohol; allow to air dry completely.
- Pinch a skinfold at the injection site; insert the needle at 45–90° into subcutaneous tissue.
- Do not aspirate for subcutaneous injections; inject slowly and steadily.
- Rotate sites systematically (abdomen, thighs, upper arms) to prevent lipohypertrophy and lipoatrophy.
- Common subcutaneous sites: abdomen (at least 2 inches from navel), outer thighs, upper arms (posterior surface).
- Wait a few seconds after injection before withdrawing needle to minimize solution leakage.
Important notes
- Use new sterile insulin syringes for each injection; dispose in a sharps container.
- Rotate injection sites systematically (abdomen, thighs, upper arms) to reduce local irritation and prevent lipoatrophy.
- Inject slowly; wait a few seconds before withdrawing the needle to minimize leakage.
- Document daily dose, injection site, and any observed effects to maintain consistency and track tolerance.
- FDA-approved Genotropin is a 191-amino-acid somatropin product supplied as a lyophilized powder for subcutaneous injection after product-specific reconstitution. Those instructions apply to that approved formulation and device.
Protocol source: PeptideDosages.com
Common questions
Is HGH 191AA different from HGH?
No. It describes the same 191-amino-acid hormone.
Can healthy adults use it for anti-aging?
Evidence in healthy older adults shows limited benefit and more adverse events.
Does more lean mass mean more muscle?
Not necessarily; lean mass includes water.
Related in Healthy Aging
Sources and further reading (6)
- DailyMed. Genotropin prescribing information.
- Endocrine Society. Evaluation and treatment of adult GH deficiency, 2011.
- Liu H, et al. Systematic review: GH in the healthy elderly. Ann Intern Med, 2007.
- Meinhardt U, et al. GH, body composition and performance in recreational athletes. Ann Intern Med, 2010.
- WADA. 2026 Prohibited List, S2.
- Source summary: PeptideDosages.com research overview (rewritten for NVO).
Laboratory research material: HGH Research Use Only