Peptides are sold in dry lyophilized powder form within sterile vials, sealed under an atmosphere of dry inert gas. They are supplied with a peptide concentration certificate and instructions on how to reconstitute them into a ready-to-use solution. The instructions suggest that the peptide can be easily reconstituted by injecting the recommended amount of an appropriate solvent into the vial with a calibrated syringe. The resulting peptide solution is then used for injections and will have the exact concentration that is guaranteed on the peptide concentration certificate.
To avoid contamination of the peptide, it is important to use only sterile equipment. This includes using sterile wipes to clean the injection area before and after each administration, as well as using needles that have been sterilized in accordance with established protocols and guidelines. The recommended needle length and gauge depends on the injection site, which can vary from person to person. Some of the most popular injection sites for peptides are the stomach, arms and thighs.
Reconstituted peptides should be stored at room temperature for up to 2 hours, and longer term storage is possible, but not recommended. They should be kept in a dry and dark place away from light. The peptide can also be frozen to extend its shelf life and stability. However, it is important to note that frozen peptides may require more time for reconstitution and may require special storage conditions (e.g., -20 or -80°C).
The most common and cost-effective solvent for peptide reconstitution is bacteriostatic water, which is typically supplied in plastic autosampler vials with a screwcap. These vials contain 0.9% benzyl alcohol, which provides a high level of protection from bacterial degradation and improves the stability of lyophilized peptides.
Some peptides are also available in solutions containing more stable solvents such as DMSO. While the peptides are much more soluble in these solvents, they require more extensive reconstitution and will require more handling during storage and injection.
When reconstituting a peptide, it is important to not spray the solution from the syringe into the vial or to shake it vigorously, as this will degrade the peptide structure. It is more effective to drip the solvent slowly into the vial and then remove the syringe. A gentle swirl of the vial in your hands or sonication may also help to dissolve the peptide, but it is not necessary and is actually more likely to damage the peptide. Also, it is highly recommended to avoid multiple freeze-thaw cycles for reconstituted peptides. This is due to their enhanced decomposition speed in solution, and the damage that each cycle causes can accumulate over time. Peptides should be stored and thawed in small aliquots to minimize the number of freeze-thaw cycles that they experience. This will also reduce the overall storage and handling costs for the peptides. peptide vials