Calculating Retatrutide Injection Volume
With 6mg of retatrutide mixed in 4mL of bacteriostatic water, your concentration is 1.5mg/mL, so you need to divide your prescribed dose (in mg) by 1.5 to get the volume to inject in mL.
Understanding Your Concentration
When you reconstitute 6mg of retatrutide powder with 4mL of bacteriostatic water, you create a solution with a concentration of:
- 6mg ÷ 4mL = 1.5mg/mL 1
This means every 1mL of your mixed solution contains 1.5mg of retatrutide 1.
Calculating Your Injection Volume
To determine how much to inject based on your prescribed dose, use this formula:
Volume to inject (mL) = Prescribed dose (mg) ÷ 1.5mg/mL 1
Common Dose Conversions for Your Concentration:
- 0.5mg dose = 0.33mL (approximately 0.3mL) 2, 3
- 1mg dose = 0.67mL (approximately 0.7mL) 2
- 2mg dose = 1.33mL (approximately 1.3mL) 2, 3
- 4mg dose = 2.67mL (approximately 2.7mL) 2, 3
- 8mg dose = 5.33mL (approximately 5.3mL) - Note: This exceeds your 4mL total volume 2, 3
- 12mg dose = 8mL - Note: This significantly exceeds your 4mL total volume 2, 3
Critical Safety Considerations
Your 4mL reconstitution volume limits you to a maximum dose of approximately 6mg (which would be the entire 4mL vial). If your prescribed dose is 8mg or 12mg, your current reconstitution is incorrect and you need to use less bacteriostatic water to achieve a higher concentration 2, 3, 1.
Dosing Based on Clinical Trial Data:
In phase 2 trials, retatrutide was administered subcutaneously once weekly with dose escalation strategies 2, 3:
- Starting doses typically began at 2mg with escalation to maintenance doses of 4mg, 8mg, or 12mg 2, 3
- The 8mg and 12mg doses used a 2mg starting dose with gradual escalation 2, 3
Measurement Best Practices
Always use a calibrated oral syringe or insulin syringe marked in 0.1mL increments to ensure accurate measurement of your dose. 1
- Never use household measuring devices (teaspoons, tablespoons) for medication measurement 1
- Metric units (mL) are the standard for all liquid medication dosing to minimize errors 1
- Ensure your syringe markings match the volume you need to draw 1
Important Caveats
If your prescribed dose requires more than 4mL of solution, you must reconstitute with less bacteriostatic water to create a more concentrated solution. For example:
- For 8mg or 12mg doses, consider using 2mL of bacteriostatic water instead, creating a 3mg/mL concentration 2, 3, 1
- Always verify your reconstitution instructions with your prescribing provider or pharmacist before proceeding 1
Retatrutide is administered subcutaneously (under the skin), not intramuscularly or intravenously. 2, 3