Retatrutide Reconstitution Guide: How to Mix and Dose Every Vial Size (2026)

> **Quick answer — how to reconstitute retatrutide (full protocol).** Reconstitute by drawing bacteriostatic (BAC) water into the lyophilized retatrutide vial slowly down the side wall, then swirl gently — never shake — until clear. The standard ratio is **2mL of BAC water per 10mg vial** (5mg/mL), so a 1mg dose = 0.2mL = 20 units on a U-100 insulin syringe; scale water proportionally for 6mg–60mg vials (see the chart below). Store the reconstituted vial refrigerated at **2–8°C, protected from light, and use within 28 days**. Retatrutide is an investigational research compound and is not FDA approved; this is educational information, not medical advice. ## What Is Retatrutide and Why Does Reconstitution Matter? Retatrutide (LY3437943) is a triple GIP/GLP-1/glucagon receptor agonist developed by Eli Lilly. In Phase 2 trials published in the *New England Journal of Medicine* (2023), participants lost an average of 17.5% of body weight at the highest dose over 24 weeks — outperforming tirzepatide and semaglutide in head-to-head data comparisons. It is currently completing Phase 3 TRIUMPH trials and is available for research use in lyophilized (freeze-dried powder) form — for the latest on [when retatrutide will be FDA approved](/guides/retatrutide-fda-approval-2026-timeline-status), see our regulatory timeline tracker. Because retatrutide powder must be dissolved before injection, proper reconstitution is essential for accurate dosing, peptide stability, and safety. This guide covers every common vial size with exact water volumes, dosing calculations, and storage requirements. --- ## Equipment You Need Before Reconstituting Retatrutide Before you begin, gather the following: - **Bacteriostatic water for injection (BAC water)** — 30mL multi-dose vial recommended - **Insulin syringe** — 1mL, 100-unit markings (U-100 syringe) - **Drawing syringe** — larger 3mL or 5mL syringe for measuring BAC water - **Alcohol swabs** — for vial tops - **The retatrutide vial** — inspect for cracks, intact lyophilized cake, no discoloration > **Critical:** Never inject BAC water directly onto the peptide powder. Insert the needle at an angle and let the liquid run down the glass wall to dissolve gently. Direct force causes aggregation. --- ## Retatrutide Reconstitution Chart: All Vial Sizes The following table shows the most practical reconstitution ratios. The standard approach is to add enough BAC water to create a round, easy-to-measure concentration. ### Standard Reconstitution Ratios | Vial Size | BAC Water Added | Concentration | Dose 1mg = | Dose 2mg = | Dose 4mg = | |-----------|-----------------|---------------|------------|------------|------------| | **6mg** | 1.0mL | 6mg/mL | 0.17mL (17 units) | 0.33mL (33 units) | 0.67mL (67 units) | | **6mg** | 2.0mL | 3mg/mL | 0.33mL (33 units) | 0.67mL (67 units) | 1.33mL (133 units)* | | **10mg** | 1.0mL | 10mg/mL | 0.10mL (10 units) | 0.20mL (20 units) | 0.40mL (40 units) | | **10mg** | 2.0mL | 5mg/mL | 0.20mL (20 units) | 0.40mL (40 units) | 0.80mL (80 units) | | **12mg** | 2.0mL | 6mg/mL | 0.17mL (17 units) | 0.33mL (33 units) | 0.67mL (67 units) | | **12mg** | 3.0mL | 4mg/mL | 0.25mL (25 units) | 0.50mL (50 units) | 1.0mL (100 units) | | **20mg** | 2.0mL | 10mg/mL | 0.10mL (10 units) | 0.20mL (20 units) | 0.40mL (40 units) | | **20mg** | 4.0mL | 5mg/mL | 0.20mL (20 units) | 0.40mL (40 units) | 0.80mL (80 units) | | **24mg** | 3.0mL | 8mg/mL | 0.125mL (12.5 units) | 0.25mL (25 units) | 0.50mL (50 units) | | **30mg** | 3.0mL | 10mg/mL | 0.10mL (10 units) | 0.20mL (20 units) | 0.40mL (40 units) | | **30mg** | 6.0mL | 5mg/mL | 0.20mL (20 units) | 0.40mL (40 units) | 0.80mL (80 units) | | **40mg** | 4.0mL | 10mg/mL | 0.10mL (10 units) | 0.20mL (20 units) | 0.40mL (40 units) | | **50mg** | 5.0mL | 10mg/mL | 0.10mL (10 units) | 0.20mL (20 units) | 0.40mL (40 units) | | **60mg** | 6.0mL | 10mg/mL | 0.10mL (10 units) | 0.20mL (20 units) | 0.40mL (40 units) | *Units over 100 require a 2mL syringe. **Why 10mg/mL is the preferred concentration:** A 10mg/mL solution means every 0.1mL (10 units on a U-100 syringe) equals 1mg. This makes mental math simple and reduces measurement errors at lower doses like 1mg or 2mg. --- ## Step-by-Step Reconstitution Instructions ### Step 1: Gather and Inspect Check the retatrutide vial for the intact lyophilized cake (white, porous solid). Discard if powder appears discolored (yellow-brown), the vial is cracked, or the vacuum seal was compromised (powder moves freely when tipped — good; loose watery powder — bad). ### Step 2: Wipe Both Vial Tops Use an alcohol swab to clean the rubber stopper of both the retatrutide vial and the BAC water vial. Allow 15–30 seconds to dry. ### Step 3: Draw the BAC Water Using your drawing syringe, pull back the plunger to load it with air equal to the volume of BAC water you plan to add. Insert the needle into the BAC water vial, push in the air (to equalize pressure), and draw the correct volume of BAC water. ### Step 4: Add Water to Peptide — Slowly and at an Angle Insert the syringe needle through the retatrutide vial stopper at a 45-degree angle. The needle tip should point toward the glass wall, not straight down at the powder. Gently push the plunger to let the water run down the side of the vial — never squirt directly onto the powder cake. ### Step 5: Do Not Shake — Gently Swirl or Roll Shaking causes peptide aggregation and can degrade retatrutide. Instead, gently roll the vial between your palms or swirl it in slow circles for 30–60 seconds. If powder remains at 1 minute, place the vial in the refrigerator for 10–15 minutes, then gently swirl again. ### Step 6: Inspect the Solution A properly reconstituted solution should be: - **Clear to pale yellow** — acceptable - **Free of visible particles** — required - **No cloudiness or turbidity** — discard if present ### Step 7: Label and Store Label your vial with the date reconstituted and the concentration (e.g., "10mg/mL — reconstituted 20 Mar 2026"). Store at 2–8°C (refrigerator). Do not freeze. Use within 28 days. --- ## Retatrutide Dosing Schedule: Research-Based Titration Protocol The following protocol is derived from the Phase 2 NEJM trial. The conservative titration shown below prioritizes tolerability and minimizes GI side effects. ### Conservative 24-Week Titration Protocol | Weeks | Weekly Dose | Notes | |-------|-------------|-------| | 1–4 | **1mg** | Starting dose; expect minimal GI effects | | 5–8 | **2mg** | Appetite suppression becomes noticeable | | 9–12 | **4mg** | Most users experience meaningful weight loss | | 13–16 | **6mg** | Escalate only if tolerating 4mg well | | 17–20 | **8mg** | Phase 2 trial's mid-high dose | | 21+ | **12mg** | Maximum studied dose; reserved for good tolerability | > **Note:** The Phase 2 trial used 1mg, 4mg, 8mg, and 12mg arms. The intermediate doses shown above (2mg, 6mg) represent clinically conservative interpolations to minimize side effects. ### Can You Stay on a Low Dose? Yes. A significant number of Phase 2 participants achieved clinically meaningful weight loss at 4mg and 8mg. The 12mg dose produced greater weight loss but also more GI-related discontinuations. If you are tolerating your current dose and seeing results, there is no requirement to escalate. --- ## Troubleshooting Common Reconstitution Problems ### "My retatrutide is still cloudy after mixing" Gentle swirling for another 60 seconds and a 15-minute rest in the refrigerator usually resolves incomplete dissolution. If the solution does not clear after refrigerating and re-swirling, discard the vial — aggregated peptide cannot be de-aggregated. ### "My vial seems like less volume than I expected" Lyophilized peptide occupies volume, so after reconstituting 10mg with 1mL of BAC water, the total volume in the vial will be approximately 1.0–1.1mL — not measurably different. You have not lost peptide. ### "The peptide powder dissolved very quickly, almost immediately" This is normal for high-quality lyophilized retatrutide. Some vials dissolve in under 30 seconds. Quick dissolution does not indicate a problem. ### "I mixed two different vials together — is that okay?" Do not combine reconstituted retatrutide vials unless they are the same concentration, preparation date, and lot number. Mixing vials of different concentrations is a common dosing error. --- ## Retatrutide vs. Tirzepatide vs. Semaglutide: Mechanism Comparison | Feature | Semaglutide | Tirzepatide | Retatrutide | |---------|-------------|-------------|-------------| | Receptors | GLP-1 | GLP-1 + GIP | GLP-1 + GIP + Glucagon | | Avg. weight loss (Phase 2/3 peak) | ~15% | ~22% | ~24% | | FDA Status | Approved (Wegovy, Ozempic) | Approved (Zepbound, Mounjaro) | Phase 3 (2026) | | Dosing frequency | Weekly | Weekly | Weekly | The additional glucagon receptor agonism is believed to be responsible for retatrutide's greater metabolic rate increase and enhanced fat oxidation compared to dual agonists. --- ## Retatrutide FDA Approval Timeline: What to Expect As of July 2026, Eli Lilly's TRIUMPH Phase 3 program is underway with four trials (TRIUMPH-1 through TRIUMPH-4) covering obesity, type 2 diabetes, and metabolic dysfunction-associated steatohepatitis (MASH). Lilly submitted an NDA in late 2025. Based on standard FDA review timelines (12 months for priority review), approval is expected in 2026–2027. The commercial name has not been finalized, though internal Lilly documentation has referenced "Orfoglipron" for the oral GLP-1 separately; retatrutide injectable is expected under a distinct brand name. --- ## Storage and Handling Summary | Condition | Pre-Reconstitution | Post-Reconstitution | |-----------|-------------------|---------------------| | Temperature | Room temp or refrigerator | 2–8°C (refrigerator only) | | Light | Protect from direct light | Protect from light | | Freeze? | Check manufacturer guidance | Never freeze reconstituted solution | | Shelf life | Per lot expiry | 28 days after reconstitution | --- For complete peptide reconstitution guidance including tirzepatide and semaglutide mixing, see our [Peptide Reconstitution Guide](/guides/how-to-reconstitute-peptides-complete-guide) and [Bacteriostatic Water Usage Guide](/guides/bacteriostatic-water-peptide-reconstitution-guide).