Choosing a Retatrutide Vial Size: 5 mg to 120 mg
What changes between a 5 mg and a 120 mg retatrutide vial, how to work out stock concentration, and how to match vial size to how fast you will use the solution.
Retatrutide is supplied in eleven vial sizes, from 5 mg to 120 mg, always in packs of ten vials from one lot. The peptide, the purity specification and the lyophilized form are the same in every size; what changes is how much material sits in each vial. That makes the choice a question of stock concentration, how quickly you will use the reconstituted solution, and cost per milligram.
Start with the stock concentration
Concentration equals the milligrams in the vial divided by the millilitres of solvent. A 10 mg vial in 2 mL gives 5 mg/mL; a 100 mg vial in 10 mL gives 10 mg/mL; a 120 mg vial in 20 mL gives 6 mg/mL. Reconstitution at 5 to 10 mg/mL in sterile water is the range most commonly cited for retatrutide.
Check that the vial can physically hold the volume you plan to add before you reconstitute. A very large vial size means a large solvent volume if you want to stay in the 5 to 10 mg/mL range, which is one reason the middle sizes are often easier to work with.
Match the vial to how fast you will use it
Once reconstituted, a vial is a perishable stock, so the size should reflect your rate of use. A small number of assays spread over weeks fits a 5 mg, 10 mg or 20 mg vial and leaves little unused solution. A programme with many replicates or arms in a short period fits a 50 mg to 120 mg vial, because one reconstitution serves the whole run and removes vial-to-vial preparation as a source of variation.
Dividing a reconstituted vial into single-use aliquots extends how much of it you can use, but avoid repeated freeze-thaw cycles and follow the stability data for your own buffer and storage conditions.
Cost per milligram
Larger vials cost less per milligram. The 100 mg and 120 mg vials are the lowest-cost way to buy retatrutide by the milligram, and the 5 mg vial is the highest. If you will use the material within a stability window that suits it, the larger vial is the economical choice; if much of it would go unused, the smaller vial is less wasteful despite the higher unit cost.
Why the ten-vial pack matters
Ten vials from one lot lets you reconstitute vials on different days as needed, keeping the rest as lyophilized stock at -20°C, and use the same lot across every arm of a study, which removes lot-to-lot variability as a confounder. If you need fewer than ten vials, email us to arrange a smaller order at the same per-vial price.
Single compound or blend?
If a design needs retatrutide and tirzepatide together, a pre-mixed 1:1 retatrutide + tirzepatide blend (30 mg of each, 60 mg total per vial) combines them in one reconstitution step. For retatrutide alone, choose the single-compound vial using the points above. Retatrutide is for laboratory research use only; nothing here is medical advice.
