Lyophilized peptides can be frozen for longer storage but reconstituted solutions belong in the fridge at 2-8°C. Freezing after mixing risks ice crystals, aggregation, and loss of potency or immune reactions, though a few users report tirzepatide surviving accidental freezes. Bac-water storage opinions differ, with some keeping it at room temperature after opening and others freezing or refrigerating it. No public stability data exist for research-grade reconstituted reta or cag, so refrigeration remains the standard advice.
What this discussion establishesWhether repeated freeze-thaw cycles of bac water affect sterility or whether freezing reconstituted peptides is ever acceptable.
Still openLong-term stability data for research-grade reta and cag after freezing or thawing.
Nothing here is advice.
Hi everyone, is it okay to freeze reconstituted reta, cag and similar peptides? I searched the forum but couldn't find any details and was hoping the experienced members could help. Thanks.
No. Freeze-dried powder peptides can be frozen, but that is mainly for long-term storage. Once mixed, peptides belong in the refrigerator at 2–8°C. Bac-water keeps the solution sterile for up to four weeks.
Some peptides have been tested and tirz can be frozen a few times after mixing. A hotel fridge froze one vial and it still worked. Others are considered a definite no. It came up in discussion before, along with notes on time convenience and reducing waste from opened bac vials.
Freezing and thawing tends to harm peptides, though the effect varies by type. Tirz might tolerate it better, but the original question was about reta and cag. With no public stability data available for research-grade mixed preparations, the recommended approach is refrigeration after reconstitution rather than freezing.
Thanks, the information on freezing unmixed peptides is really mixed. One source says not to, another says it is fine. I will put the ones I am waiting on in the freezer. That article will be useful if I decide to change peptides later.
Ice crystals form during freezing and some peptides break down depending on their sequence. Highly concentrated pockets appear where peptides clump together through hydrophobic interactions and stay that way after thawing. At best they lose activity; at worst they could trigger immune responses. Freezing a solution is not recommended without a stabilizer like glycerol and a surfactant to stop aggregates.
I store my labeled peptides in a jar that sits inside the freezer. Before mixing a fresh vial I move it over to the fridge for a full day. It stays in there the entire time until I finish it. This method has worked out fine so far and I have run into zero trouble.
Do not freeze reconstituted reta. The lyophilized form is fine in the freezer. Once mixed, vials go in the fridge. On mixing day they come straight from the freezer onto the tray and are warm enough by the time bac water is added.
Keeping them in the freezer is unnecessary. Room-temperature bac water warms the freezer-cold lyophilized material right away during reconstitution. There are already many threads on this topic.
I was already fairly sure it would not matter, but it probably does not hurt either. I still keep my bac in the fridge once opened.
I freeze my bac after opening and thaw or refreeze it as needed during reconstitution. There is no logical scientific reason this should be a problem in a home setting, even though some directions say to store it at room temperature.
These are just personal preferences. Mine goes back into the cabinet in the laundry room.
Thanks for mentioning that. Keeping things in a cool dark place is difficult in summer without central air conditioning. I have been storing it in the basement with a dehumidifier and desiccant packets. Good to know it handles room temperature fine.
Would repeated freezing and thawing of bac water create condensation that could affect sterility?
There is a lot of information here, thank you. I will keep looking into it to be sure everything is safe. As a student nurse I am comfortable with mixing and preparation but storage and chemical stability are not my strong areas. I did try the search function but sometimes the volume of results is overwhelming.
I thought bac water was meant to stay at room temperature after puncture so the benzyl alcohol works best against bacteria. That is the reason it is added, right?
No central air conditioning? I have heard stories about places like that. It reached 115 degrees here yesterday.
I already dislike summer and this makes me dislike it even more.
The real question is why anyone would want to freeze reconstituted peptides in the first place.
It is winter there now though, so that helps.
Some people have talked about freezing reconstituted vials after receiving several at once from a compounder, but there is no real benefit to mixing at home and then freezing them.
Yes, thankfully it is winter for me.
To make them last longer than the 28 days suggested for bac water and to extend the life of the peptides themselves before they are mixed.
I like the southwest and hope to retire there someday in a thick-walled adobe house with a pool, but I have only visited in winter. The dry heat in Phoenix must help. I remember an archaeological dig near Tucson at high elevation where 95 degrees felt manageable because of low humidity.
Not many microbes grow at zero Fahrenheit. Freezing also offers efficiency and convenience when it is time to use the material later.
So the advice is not to freeze after reconstitution but it is acceptable to freeze before reconstitution?
I am also neurodivergent and sometimes the amount of information is hard to sort through. Search terms in my head do not always match the ones used on the forum. Using a search engine with site: plus the forum address can help narrow results. The bookmark feature is also useful for saving helpful posts with custom labels.
Thank you for taking the time to share that and for mentioning your own experience. Sometimes I get overloaded too, and this search approach sounds very practical.
Correct. After reconstitution they go in the fridge.
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