Reconstitution Calculation for 10 mg/mL Concentration
Add 1 mL of bacteriostatic water to a 10 mg vial of retatrutide to achieve a concentration of 10 mg/mL.
Mathematical Basis
The calculation follows standard pharmaceutical reconstitution principles where the desired concentration determines the volume of diluent needed 1:
- Formula: Volume of diluent = (Amount of drug in vial) ÷ (Desired concentration)
- Calculation: 10 mg ÷ 10 mg/mL = 1 mL of bacteriostatic water
Important Reconstitution Considerations
Volume Displacement Effect
- The lyophilized powder itself contributes approximately 1 mL to the final volume after reconstitution 1, 2
- Therefore, adding 1 mL of bacteriostatic water will yield approximately 2 mL total volume at a concentration of 5 mg/mL, not 10 mg/mL
- To achieve exactly 10 mg/mL, you would need to account for powder displacement and add slightly less diluent, or accept a final concentration closer to 5 mg/mL
Proper Aseptic Technique
- Sanitize the vial stopper with 70% isopropanol before needle insertion to prevent contamination 1
- Maintain strict sterile technique throughout, avoiding contact of needle, syringe, or stopper with non-sterile surfaces 1
- Inject the diluent slowly down the side of the vial to minimize foaming and preserve solution integrity 1
- Gently swirl (do not shake vigorously) until the powder is fully dissolved 1
- Perform visual inspection after mixing for clarity and absence of particulate matter 1
Storage and Stability
- Label the reconstituted vial with concentration, reconstitution date, and beyond-use date 1
- Bacteriostatic water contains approximately 0.9% benzyl alcohol preservative, permitting multi-dose use for up to 28 days when refrigerated at 2-8°C (36-46°F) 1
- Discard if discolored or contains particulate matter 1
- Reconstituted solutions have limited stability; use within the recommended timeframe 1, 2
Critical Pitfall to Avoid
- Never use sterile water for injection without preservative for multi-dose vials, as this significantly increases contamination risk 1
- The powder displacement effect means your actual final concentration may differ from the calculated value unless you account for the approximately 1 mL volume contribution from the powder itself 1, 2