LY3437943 reconstitution protocol

This protocol describes the reconstitution and storage of lyophilized LY3437943 in standard research workflows. LY3437943 is a triple GIP/GLP-1/glucagon receptor agonist studied in Phase 2 research for incretin pharmacology and energy balance. Values below are derived from published handling literature; experimental design parameters are the responsibility of the qualified investigator.

At a glance

Parameter	Value
Recommended diluent	Bacteriostatic Water (USP, 0.9% benzyl alcohol)
Recommended volume (10 mg vial)	2.0 mL
Final concentration	5 mg/mL
Stability — lyophilized	≥24 months at -20 °C, light-protected, sealed
Stability — reconstituted	30 days at 2–8 °C in original vial
Freeze-thaw	Avoid on reconstituted solution. Aliquot if longer-term storage needed.

Procedure

1. Equilibrate. Allow the sealed vial to come to room temperature before reconstitution.
2. Sterile prep. Wipe the stopper with isopropyl alcohol and allow to dry. Use a sterile syringe with a 21G or larger needle.
3. Inject diluent slowly. Direct the stream along the inner glass wall — not directly onto the lyophilized cake.
4. Dissolve gently. Swirl in a slow rotational motion. Do not shake. The cake should dissolve within 30–60 seconds.
5. Verify. Solution should be clear and colorless. If cloudy or discolored, do not use — contact Merit (info@meritpeptides.com).

Compound notes

LY3437943 is a 39-amino-acid compound engineered to activate all three incretin receptors. Like tirzepatide it has a fatty-acid modification that extends half-life into the once-weekly range (~6 days reported in human PK studies). The molecule is more sensitive to repeated freeze-thaw than tirzepatide due to its higher molecular weight (~5,419 Da) and greater conformational complexity — aliquot the moment you reconstitute if extended storage is planned.

Storage

Reconstituted LY3437943 is stable for approximately 30 days at 2–8 °C in the original vial. Beyond that, aliquot into sterile single-use tubes and freeze at -20 °C or -80 °C. Avoid freeze-thaw on the reconstituted form. Lyophilized stability is at least 24 months at -20 °C light-protected.

Notes

This protocol describes reconstitution parameters used in published compound-handling literature. It is not a recommendation for any particular study design. Selection of concentration, interval, and route is the responsibility of the qualified investigator under appropriate institutional oversight. For research use only. Not for human or veterinary use.

References

1. Jastreboff AM, Kaplan LM, Frías JP, et al. Triple-Hormone-Receptor Agonist LY3437943 for Obesity — a Phase 2 Trial. NEJM 2023;389:514–526. PMID: 37366315
2. Coskun T, Urva S, Roell WC, et al. LY3437943, a novel triple glucagon, GIP, and GLP-1 receptor agonist for glycemic control and weight loss. Cell Metab 2022;34:1234–1247. PMID: 35985288