Retatrutide Reconstitution Calculator & Dosing Guide
The next-generation triple agonist: vial ratios, syringe markings, titration schedule up to 12 mg, and handling guidance for this emerging compound.
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Open Calculator →What Is Retatrutide?
Retatrutide (LY3437943) is a triple-receptor agonist developed by Eli Lilly that targets the GLP-1, GIP, and glucagon receptors simultaneously. The glucagon component is the novel piece — it increases energy expenditure, complementing the appetite-suppression effects of GLP-1/GIP. In Phase 3 trials, 12 mg retatrutide achieved approximately 24% body weight reduction at 48 weeks, the highest efficacy reported for any injectable weight-loss agent to date.
As of 2026, retatrutide is not FDA-approved. Lilly is expected to file for approval in 2026–2027. Compounded retatrutide is available through some 503A pharmacies for research purposes, but regulatory status is fluid. Verify legality in your jurisdiction.
Common Reconstitution Ratios
| Vial size | BAC water | Concentration | 2 mg draw (U100) | 6 mg draw (U100) | 12 mg draw (U100) |
|---|---|---|---|---|---|
| 10 mg | 1 ml | 10 mg/ml | 20 units | 60 units | exceeds 1ml |
| 10 mg | 2 ml | 5 mg/ml | 40 units | exceeds 1ml | exceeds 1ml |
| 30 mg | 2 ml | 15 mg/ml | 13 units | 40 units | 80 units |
| 30 mg | 3 ml | 10 mg/ml | 20 units | 60 units | exceeds 1ml |
For the full titration ladder on a single syringe draw, the 30 mg vial + 2 ml BAC water (15 mg/ml) covers every step from 2 mg up to 12 mg within a 1 ml U100 syringe.
Retatrutide Titration Schedule
Phase 3 trial protocol (TRIUMPH series) escalates every 4 weeks. Many users follow a similar cadence for compounded retatrutide, though some extend each step to 6 weeks to manage side effects.
| Week | Dose | Notes |
|---|---|---|
| 1–4 | 2 mg | Starting dose — tolerance phase |
| 5–8 | 4 mg | Step-up |
| 9–12 | 6 mg | Step-up |
| 13–16 | 8 mg | Step-up |
| 17–20 | 10 mg | Common maintenance |
| 21+ | 12 mg | Max trial dose |
Side effects scale with dose. Nausea, constipation, and injection-site reactions are common in the first weeks after each escalation. Users frequently report better tolerance when they hold steps longer or micro-titrate between approved steps.
Storage and Handling
- Pre-reconstitution: Freezer-stable long term.
- Post-reconstitution: Refrigerate at 36–46°F. Stable ~28 days.
- No freeze-thaw cycles.
- Protect from light — use amber vials.
- Discard if cloudy, discolored, or contains particulates.
Frequently Asked Questions
What is retatrutide?
A triple agonist (GLP-1 / GIP / glucagon) developed by Eli Lilly. In Phase 3 trials (TRIUMPH-4), 12 mg achieved ~24% weight loss at 48 weeks. Not yet FDA-approved.
How do I reconstitute retatrutide?
Most common: 30 mg vial + 2 ml BAC water → 15 mg/ml, which fits every titration dose in a U100 syringe. Smaller 10 mg vials work too; see the reconstitution table above.
What is the retatrutide titration schedule?
Trial protocol: 2 → 4 → 6 → 8 → 10 → 12 mg weekly, 4 weeks at each step. Real-world users often hold longer to tolerate.
Is retatrutide FDA approved?
Not as of 2026. Phase 3 trials are ongoing; Lilly is expected to file for approval in 2026–2027. Compounded availability exists but regulatory status varies. Verify legality in your area.
How does retatrutide compare to tirzepatide and semaglutide?
In head-to-head trial data, retatrutide at 12 mg showed higher weight loss (~24%) than tirzepatide at 15 mg (~20%) or semaglutide at 2.4 mg (~15%). The additional glucagon agonism boosts energy expenditure, but side effect profile is also more pronounced.
Track Your Retatrutide Protocol in Stackr
Log weekly doses, titration progression, side effects, and injection sites.
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Stackr is a personal supply and protocol tracking tool. Nothing on this page is medical advice. Retatrutide is an investigational compound that has not received FDA approval. Availability, legality, and safety profile are subject to change. Always consult a qualified healthcare professional.