How can I obtain a 2 mg/mL concentration from a 36 mg vial of retatrutide?

Reconstituting Retatrutide 36mg to Achieve 2mg/mL Concentration

Direct Answer

To obtain a 2 mg/mL concentration from a 36 mg vial of retatrutide, add 18 mL of sterile bacteriostatic water or sterile water for injection to the vial 1.

Calculation Method

The concentration calculation follows the standard pharmaceutical dilution principle where:

• Concentration (mg/mL) = Total drug amount (mg) ÷ Volume of diluent (mL) 2
• For your specific case: 36 mg ÷ 18 mL = 2 mg/mL 2
• This formula applies universally to peptide reconstitution when manufacturer-specific instructions are unavailable 1

Step-by-Step Reconstitution Protocol

Preparation Phase

• Use strict aseptic technique throughout the entire procedure to prevent contamination and maintain drug sterility 1
• Allow the vial to reach room temperature before opening to avoid condensation on the powder, which can affect concentration accuracy 2
• Gather supplies: 36 mg retatrutide vial, 18 mL sterile bacteriostatic water or sterile water for injection, appropriate sterile syringes for measuring 1, 3

Reconstitution Steps

• Draw up exactly 18 mL of sterile diluent using a sterile syringe 3
• Inject the diluent slowly down the side of the vial, not directly onto the powder, to minimize foaming 1
• Gently swirl (do not shake vigorously) until the powder is completely dissolved 3
• Visually inspect the solution for particulate matter and discoloration before use - the solution should be clear 1

Labeling and Storage

• Label the reconstituted vial immediately with: medication name and concentration (retatrutide 2 mg/mL), date and time of reconstitution, expiration date/time, and your initials 3
• Store at 4°C (refrigerated) unless manufacturer specifies otherwise 2
• Discard after 24 hours if using sterile water without preservative; bacteriostatic water may extend stability 3

Critical Safety Warnings

Dosing Error Prevention

• Reconstituting without manufacturer-specific instructions carries significant patient safety risks, including incorrect concentration leading to dosing errors 1
• Always verify your calculation before preparing: 36 mg ÷ desired concentration (2 mg/mL) = 18 mL required 2
• Use an analytical balance if weighing powder from bulk sources 2

Contamination and Stability Risks

• Improper sterile technique can cause contamination and loss of drug potency 1
• Some peptides are particularly unstable and should not be stored after reconstitution 2
• Retatrutide stability data after reconstitution is limited in published literature, so prepare immediately before use when possible 1

Diluent Compatibility

• Incompatibility with certain diluents can cause drug degradation 1
• Follow manufacturer recommendations for solvents when available; sterile water is generally safe for peptides when specific guidance is absent 2
• Never mix with alkaline solutions or incompatible medications 4

Clinical Context for Retatrutide

Retatrutide is a triple-hormone receptor agonist (GLP-1, GIP, and glucagon receptors) used for obesity and type 2 diabetes 5, 6. In clinical trials, doses ranged from 1 mg to 12 mg weekly, with the 12 mg dose showing 24.2% weight reduction at 48 weeks 5. The most common adverse events are gastrointestinal (nausea, diarrhea, vomiting) and dose-dependent increases in heart rate 5, 7.

Verification Before Administration

• Double-check that your final concentration is 2 mg/mL by confirming 36 mg powder was dissolved in exactly 18 mL 2
• If you need a different final volume while maintaining 2 mg/mL concentration, adjust proportionally (e.g., 12 mg powder requires 6 mL diluent) 2
• Document the reconstitution in the patient's medical record 3