Shelf Life of Lyophilized Peptides

[CheetosYum]

Vendor kit labels state that lyophilized peptides remain viable for 2 years starting at the manufacturing date — does that figure presume storage at room temperature? And is purity maintained throughout that entire period?

I'm considering a personal stockpile (roughly a 3-year supply) of one particular batch that was made 8 months ago. Would it keep in the freezer, or should I wait for a newer batch instead? My worry is that it has likely been stored at room temp in a warehouse for those 8 months.

 

[Jh02050]

Last week I sent a 30mg Tirzepatide vial to TrustPointe Analytics for purity testing. It came back at 99.8% purity, and this batch had a manufacturing date of 10/02/25. How that vial was kept over that stretch is anyone's guess. That particular vial isn't coming back to me, though the others are kept in my freezer.

 

[eidos]

CheetosYum said:

Vendor kit labels state that lyophilized peptides remain viable for 2 years starting at the manufacturing date — does that figure presume storage at room temperature? And is purity maintained throughout that entire period?

I'm considering a personal stockpile (roughly a 3-year supply) of one particular batch that was made 8 months ago. Would it keep in the freezer, or should I wait for a newer batch instead? My worry is that it has likely been stored at room temp in a warehouse for those 8 months.

Nope — 2 weeks is all you get. Way past the point already. Just box them up and ship them my way; I run an environmentally friendly disposal service.

(okay, my turn for that one; it still cracks me up every time)

The “official” datasheets put it at 1 year refrigerated, 2 years frozen.

Around here, the prevailing bet is that it stretches further. That's because similar reports exist for other peptides kept under identical conditions.

A year or 2 from now, once somebody who's been sitting on a stash sends one off for testing, we'll finally have real numbers on what's still in those vials.

As for me, I'm leaning on the fact that these vials are overfilled by roughly 20%, which should offset whatever degradation occurs. My upcoming order will cover 2 years, possibly 3 years, of Reta. Fridge storage for me, not the freezer — I want to lower the chance of mannitol crystallizing in the excipient. Somebody in a recent thread mentioned their vendor warned against freezing, though they never clarified if the excipient was the reason.