Why does Camargo recommend not to use a CMO’s testing lab for development? CMO labs are tailored for commercial production, characterized by many SOP’s and schedules. During early drug development we need answers quickly, sometimes even approximate answers. We’re not bound at this stage by GMPs. We have several outside labs, so we can select one that is available NOW. Further, we often need specialized testing simply not available at a CMO, such a mass spectroscopy for impurity identifications. When preparing Phase 3 clinical materials or stability batches we transfer the methods to the commercial manufacturer. This transfer assures us that the methods are rugged.