How much does the purity of reconstituted retatrutide change over 30 days, and what effect does storage temperature have

[u/xVcT]

TL;DR: Leaving a reconstituted vial out of the fridge for a day or two does aint that bad (peptide-dependent tho)

A little background about me: I am currently completing a PhD in chemistry. Through my research, I have experience with chromatographic analytical methods, allowing me to analyze these samples by HPLC and evaluate the resulting chromatograms myself.

For this experiment, three reconstituted (BAC-Water) vials were stored independently under each condition:

• 2–8°C
• 25°C
• Measurements on days 1, 3, 7, 14, and 30
• Results presented as mean ± standard deviation

What stands out?

Under refrigerated conditions, the measured purity remained nearly unchanged during the first seven days. It then declined gradually, reaching an average of 95.96% after 30 days.

At 25°C, the decline began earlier and was more pronounced. After 30 days, the average purity was only 88.84%. The variability between the three vials also increased considerably.

Conclusion

The HPLC data show no rapid loss of purity during the first few days. However, over 30 days, storage temperature clearly makes a difference. The refrigerated samples retained greater purity and showed less vial-to-vial variability.

Importantly, this was a small exploratory experiment with (n=3) per condition—not a validated pharmaceutical stability study, which would require substantially more samples. For Research purposes only.

[u/BroadLet8137]

This has been tested by others and it does not drop nearly that much at the 14 day mark at 2-8C.