Short answers to the questions researchers ask most about storing, mixing and handling tesamorelin, the 44-residue GHRH analogue. Each answer reflects the compound’s own chemistry and agrees with our storage and reconstitution pages.
How long does tesamorelin last after mixing?
About a week at most, kept at 2 to 8 °C in the dark. The approved formulation is discarded 7 days after mixing (US prescribing information, 2025), and our guidance applies the same limit to a research vial. The full windows are on how long does tesamorelin last.
Why does tesamorelin have a shorter mixed life than other peptides?
It keeps three reactive residues of the native GHRH sequence. Asparagine 8 deamidates, aspartate 3 isomerises or cleaves (Bongers, International Journal of Peptide and Protein Research, 1992), and methionine 27 oxidises (Campbell, Peptides, 1994). Each of these products is far less active than the parent peptide, and none of them changes how the solution looks.
How long does lyophilised tesamorelin last?
Years, when sealed, dry and cold. One supplier rates the solid at least 4 years at -20 °C (Cayman Chemical, product information). The degradation routes that limit the mixed solution all need water, so the dry cake is very stable.
Can I freeze tesamorelin?
The sealed lyophilised vial can go in the freezer. A mixed solution should never be frozen: ice crystals concentrate the peptide and drive aggregation of its helical region, and both approved formulations say not to freeze the mixed solution.
What does tesamorelin dissolve in?
Bacteriostatic water is the standard diluent for a vial that will be accessed more than once. Tesamorelin carries a strong positive charge from six arginines and two lysines, so it dissolves readily in water without acid. With 2 mL of water a 10 mg vial gives 5 mg/mL and with 1 mL it gives 10 mg/mL, as set out on the tesamorelin reconstitution page; the chemistry is on the solubility page.
Why did my tesamorelin go cloudy or gel?
Tesamorelin forms a long amphipathic helix that can self-associate. Shaking, high concentration and warm storage all push it towards haze or gel. Haze that clears within 10 to 15 minutes of gentle swirling is slow dissolution; haze, strands or gel that persist mean the vial is discarded. See why peptides gel or go cloudy.
Should tesamorelin be mixed in saline or a buffer?
Not for storage. Neutral pH speeds deamidation at asparagine 8, and GHRH peptides are most stable at pH 4 to 5 (Bongers, International Journal of Peptide and Protein Research, 1992). A supplier describes tesamorelin acetate as sparingly soluble in phosphate-buffered saline and advises against keeping that solution beyond a day (Cayman Chemical, product information).
Does tesamorelin need to be protected from light?
Yes. Light promotes oxidation of methionine 27 and, to a lesser extent, the two tyrosines. The approved product is kept in its box for light protection (US prescribing information, 2025), and research vials are best kept boxed both before and after mixing. A mixed vial in the fridge is still exposed to light each time the door opens, so the box stays on.
Can mixed tesamorelin be kept at room temperature?
For a research vial, no: once mixed it goes in the fridge at 2 to 8 °C, and the 7-day limit applies. The approved 11.6 mg formulation is labelled for room-temperature storage after mixing, but that instruction is tied to its own excipients (US prescribing information, 2025). Warmth speeds both deamidation and oxidation in an unformulated solution.
Is a clear tesamorelin solution always still good?
Not necessarily. Deamidation at asparagine 8 and oxidation at methionine 27 do not change how the solution looks, so a vial past 7 days is discarded even if it is clear. Cloudiness, gel, particles or colour are additional reasons to discard it sooner. More on what changes mean is on the stability page.
Sources: Bongers J et al., Int J Pept Protein Res 1992 (PMID 1428526); Campbell RM et al., Peptides 1994 (PMID 7937325); Cayman Chemical, tesamorelin (acetate) item 42498 product information; US prescribing information for tesamorelin, revised 2025.
All products supplied by Vistara Labs are intended for laboratory research use only. They are not drugs, are not approved for human or veterinary use, and are not intended to diagnose, treat, cure or prevent any condition. Nothing on this page constitutes medical advice or guidance for use in humans.
