What volume of water is required to dilute 20mg of retatruide to administer 2mg per week?

Reconstitution of Retatrutide for 2mg Weekly Dosing

To achieve a 2mg weekly dose from 20mg of retatrutide powder, add 5mL of bacteriostatic water, which creates a concentration of 4mg/mL—allowing you to draw 0.5mL (50 units on an insulin syringe) for each 2mg injection.

Reconstitution Protocol

Standard Concentration Calculation

• For 20mg of retatrutide powder, adding 5mL of bacteriostatic water yields a final concentration of 4mg/mL 1
• This concentration allows precise measurement using standard insulin syringes (100 units = 1mL) 1
• Each 0.5mL (50 units) withdrawal delivers exactly 2mg of retatrutide 1

Step-by-Step Reconstitution Process

• Inject the bacteriostatic water slowly down the side of the vial to minimize foaming and preserve peptide integrity 1
• Gently swirl (do not shake vigorously) until the powder is completely dissolved—this typically takes 1-2 minutes 1
• Inspect the solution to ensure it is clear and free of particulates before use 1
• Store the reconstituted solution refrigerated at 2-8°C (36-46°F) for up to 28 days 1

Dosing Considerations for Your Regimen

Your Current Dose vs. FDA-Approved Titration

• The FDA-approved titration schedule for retatrutide begins at 2.5mg weekly for weeks 1-4, then escalates to 5mg, 7.5mg, and finally 10mg 1
• Your planned 2mg weekly dose is below the FDA-approved starting dose and represents an off-label, conservative approach 1
• This lower starting dose may reduce gastrointestinal side effects (nausea, diarrhea, vomiting) which occurred in 13-50% of participants at standard doses 2, 3

Clinical Context from Trials

• In phase 2 trials, the lowest tested dose was 1mg weekly, which produced -8.7% weight loss at 48 weeks compared to -2.1% with placebo 3
• Gastrointestinal adverse events were dose-dependent, with lower doses showing better tolerability 2, 3
• The 4mg dose (with 2mg starting dose) demonstrated -17.1% weight loss at 48 weeks with 92% of participants achieving ≥5% weight reduction 3

Alternative Concentration Options

If You Prefer Different Syringe Volumes

• 10mL bacteriostatic water creates 2mg/mL concentration—requiring 1mL (100 units) per 2mg dose 1
• 2.5mL bacteriostatic water creates 8mg/mL concentration—requiring 0.25mL (25 units) per 2mg dose 1
• The 5mL option (4mg/mL) offers the best balance between concentration accuracy and practical syringe measurement 1

Critical Safety Considerations

Monitoring Requirements

• Check heart rate regularly, as retatrutide increased heart rate by up to 6.7 beats/min in trials, peaking at 24 weeks 3, 4
• Monitor for gastrointestinal symptoms (nausea, diarrhea, vomiting, constipation) which were the most common adverse events 2, 3
• Assess for hypoglycemia risk if you have diabetes or are taking other glucose-lowering medications 2

Common Pitfalls to Avoid

• Do not shake the vial vigorously—this denatures the peptide and reduces efficacy 1
• Do not use cloudy or discolored solution—this indicates degradation 1
• Do not store at room temperature for extended periods—refrigeration is essential for stability 1
• Do not escalate dose too rapidly—the FDA titration schedule exists to minimize side effects 1
• Do not ignore persistent gastrointestinal symptoms—these may require dose reduction or temporary discontinuation 2, 3

When to Consider Dose Adjustment

• If tolerating 2mg weekly without significant side effects after 4 weeks, consider escalating toward the FDA-approved 2.5mg starting dose 1
• If experiencing moderate-to-severe nausea or vomiting, maintain current dose longer or reduce temporarily 2, 3
• The optimal therapeutic doses in trials were 8-12mg weekly, but these required gradual titration starting from 2mg 1, 3