You ship it as a dry/lypohilized powder, both semaglutide and tirzepatide survives long China->Europe shipping in the summer just fine, with customs delays. The testing I've seen showed 99.965% purity of semaglutide after 22 days in shipping from China to Poland during April. Tirzepatide shows 99.064% purity after 58 days of shipping in October-November. These didn't start out at 100.00% purity either, so they likely experienced absolutely minimal degradation in shipment.

You reconstitute it with Bacteriostatic Water which is available without a prescription in the USA and contains 0.9% benzyl alcohol to inhibit bacterial growth.

If you're particularly concerned you buy a 0.22 micrometer PVDF "syringe filter" and pump it through that to another, fresh/sealed sterile vial which you can get for like $2.00 from a medical supply company (the syringe, filter, and vials are gamma-irradiated to destroy any remnants of RNA/DNA). That size filtration will filter out any lifeforms (fungal, bacterial, viral) while allowing the peptide/drug itself to pass through. So you get a guaranteed sterile solution out of the filter.