Written by PX1 Research Team
PX1 chemists and research educators with hands-on experience in US-based peptide manufacturing, HPLC / mass-spectrometry lot testing, and endotoxin QC. All content is citation-backed and peer-reviewed for accuracy.
Retatrutide Dosage: A Research Dosing Reference
Research Guide
Reviewed By
PX1 QC — Analytical Chemistry Team
Every article is reviewed by PX1's in-house analytical team for accuracy on mechanism, dosing ranges reported in the literature, and lab-handling guidance. We do not publish clinical or medical advice.
Quick answer
Retatrutide dose ranges from published Phase 2 data, titration structure, reconstitution math, and lab-handling notes for researchers.
Key takeaways
- Lot-specific HPLC purity ≥99%
- LC-MS mass matching expected 4731.6 Da
- LAL endotoxin <10 EU/mg
- Karl Fischer moisture within spec
Context
Retatrutide (LY-3437943) is investigational. Dosing information in this article is drawn from published Phase 2 clinical trial protocols and is presented as a reference for laboratory research only. It is not medical advice and not a use-in-humans recommendation.
Phase 2 published dose range
The pivotal Phase 2 obesity trial (Jastreboff et al., NEJM 2023) evaluated retatrutide at once-weekly doses of 1, 4, 8, and 12 mg over 48 weeks, following a stepped titration to reduce GI adverse events. Dose-response was clean: higher doses produced larger reductions in body weight, hepatic fat, and HbA1c.
Titration structure reported in trials
The Phase 2 titration used incremental weekly step-ups (typical increments of 2–4 mg per step) with 4-week hold periods before the next escalation. Rapid titration was associated with GI adverse events; slower titration was better tolerated.
Reconstitution math (research)
A common lab reconstitution for a 10 mg lyophilized vial uses 2 mL of bacteriostatic water, yielding 5 mg/mL. Withdrawal for a target study dose is then calculated as:
`volume (mL) = target dose (mg) / concentration (mg/mL)`
At 5 mg/mL, a 4 mg study dose corresponds to 0.8 mL. Confirm calculations against the specific vial fill and diluent volume in your protocol.
Half-life and dose interval
Retatrutide's fatty-acid side chain binds serum albumin and extends half-life to approximately 6 days, supporting the once-weekly dosing interval used in trials.
Handling
Store lyophilized vials at 2–8°C for long-term stability; ambient shipping windows are supported by the peptide's stability profile. Reconstituted material is typically stored refrigerated and used within 30 days in research settings.
Documentation to verify before use
- Lot-specific HPLC purity ≥99%
- LC-MS mass matching expected 4731.6 Da
- LAL endotoxin <10 EU/mg
- Karl Fischer moisture within spec
PX1 publishes all four per lot at /purity-reports.
Research use only. Not for human consumption. Not intended to diagnose, treat, cure, or prevent any disease.