Some medications, including many GLP-1 formulations, degrade outside a defined temperature range. Cold chain covers the packaging, coolant, transit time and carrier selection that keep them within it.
A cold-chain failure is not always visible. The parcel arrives, the patient uses it, and the only symptom is a therapy that appears not to work, which surfaces later as churn.
Not every compounding pharmacy is qualified for cold-chain shipping, which is why it has to be an input to routing rather than an assumption.
Cold-chain capability constrains which pharmacies can fill which orders, and therefore your real state coverage for temperature-sensitive therapies. It is a common late discovery in GLP-1 launches.
Cold chain, in practice
Injectable GLP-1 formulations are the common case in direct-to-consumer telehealth. Some peptide preparations also require temperature control. Routing only selects pharmacies qualified for the compound.