GDF-8 Dosing Calculator
GDF-8 (Myostatin): Muscle growth negative regulator guide.
Pre-filled with the most-reported community reconstitution protocol for GDF-8. See how 1 mL and 2 mL of bacteriostatic water change concentration and syringe-draw volume, then adjust the calculator below for your own vial.
Quick answer · Community-reported standard
A 5 mg vial of GDF-8 reconstituted with 2 mL of bacteriostatic water yields a concentration of 2.50 mg/mL. At that concentration, a 200 mcg dose of GDF-8 equals 8 units on a U-100 insulin syringe (0.080 mL). GDF-8 is typically administered once daily via subcutaneous.
GDF-8 reconstitution: 1 mL vs 2 mL bac water
Bacteriostatic water volume is flexible. Less water means higher concentration and smaller injection volumes; more water means lower concentration and easier dose precision. Both options below are valid for a 5 mg vial.
| BAC water added | Concentration | Volume per 200 mcg dose | Draw on U-100 syringe (units) |
|---|---|---|---|
| 1 mL | 5.00 mg/mL | 0.040 mL | 4 units |
| 2 mL | 2.50 mg/mL | 0.080 mL | 8 units |
Calculate your GDF-8 dose
Alternative GDF-8 protocols
Beyond the default above, GDF-8 is also reported in the following protocols. Use these as starting points and recalculate with the tool above.
Conservative Assessment Protocol
Community- Dose
- 100-200 mcg
- Frequency
- Once daily
- Duration
- 4 weeks
- Route
- Subcutaneous
Lower dose for initial tolerance assessment; minimal community experience to guide dosing
Anti-myostatin antibody (MYO-029) Phase I/II
Clinical- Dose
- 1, 3, 10, or 30 mg/kg
- Frequency
- Single IV infusion
- Duration
- Single dose with 6-month follow-up
Dose-escalation safety study in adult muscular dystrophy patients
Domagrozumab (PF-06252616) Phase 2 DMD
Clinical- Dose
- 5 mg/kg (low), 20 mg/kg (mid), 40 mg/kg (high)
- Frequency
- Every 4 weeks IV
- Duration
- 48 weeks treatment period
Phase 2 trial in ambulatory DMD patients
ACE-031 Phase 1 healthy volunteers
Clinical- Dose
- 0.02 to 3 mg/kg
- Frequency
- Single SC injection
- Duration
- Single dose with follow-up
Dose-escalation study; higher doses showed lean mass increases
Bimagrumab Phase 2 sarcopenia
Clinical- Dose
- 70 mg SC every 4 weeks
- Frequency
- Every 4 weeks
- Duration
- 24-48 weeks
Lower doses than IV formulation due to different pharmacokinetics
GDF-8 reconstitution & storage
Myostatin inhibitor biologics are supplied as sterile solutions for injection or as lyophilized powder requiring reconstitution with sterile water for injection per manufacturer protocol. Specific preparation varies by product.
Biologic myostatin inhibitors should be stored at 2-8 degrees C (refrigerated). Do not freeze unless product labeling specifically permits it. Protect from light. Reconstituted solutions should be used within the timeframe specified in product documentation.
GDF-8 dosing FAQ
How much bacteriostatic water should I add to a 5 mg vial of GDF-8?
The community standard is 2 mL of bacteriostatic water for a 5 mg GDF-8 vial. That gives a concentration of 2.50 mg/mL, so a 200 mcg dose is 8 units on a U-100 insulin syringe. Adding 1 mL instead doubles the concentration to 5.00 mg/mL and halves the draw to 4 units. Less water = smaller injection volume but harder to measure precisely.
How many syringe units is a 200 mcg dose of GDF-8?
On a standard U-100 insulin syringe, a 200 mcg dose of GDF-8 is 8 units when the 5 mg vial is reconstituted with 2 mL of bacteriostatic water (2.50 mg/mL). If you use 1 mL of bac water instead, draw 4 units (5.00 mg/mL).
What is the standard GDF-8 dose?
Community-reported protocols for GDF-8 typically use 200 mcg–400 mcg once daily via Subcutaneous. 200 mcg is a common starting dose. Myostatin propeptide injection to bind and inhibit active myostatin; very limited community use data
How long does a vial of GDF-8 last at 200 mcg once daily?
A 5 mg vial of GDF-8 contains roughly 25 doses at 200 mcg per injection. At once daily dosing, that is approximately 25 days (about 4 weeks) of supply per vial. Reconstituted GDF-8 should generally be used within 28 days when refrigerated.
Where do you inject GDF-8?
GDF-8 is typically injected subcutaneous. Common sites reported in the literature and by users include: Intravenous infusion (monoclonal antibodies), Subcutaneous (some antibodies, ActRIIB-Fc), Intramuscular (gene therapy approaches). Rotate sites with each injection to reduce localized irritation.
Can I use sterile water instead of bacteriostatic water for GDF-8?
Bacteriostatic water (containing 0.9% benzyl alcohol as a preservative) is strongly preferred for multi-dose vials like GDF-8 because it inhibits microbial growth and lets a single vial be used over multiple weeks. Sterile water has no preservative and should generally be reserved for single-use preparations only.
More on GDF-8
Medical Disclaimer
This website is for educational and informational purposes only. The information provided is not intended to diagnose, treat, cure, or prevent any disease. Always consult with a qualified healthcare professional before using any peptide or supplement.