This case study details the collaboration between a client and a GMP laboratory to develop customized assays and conduct complex testing for two inhaled drug-device combination products. The client required methodologies and testing to generate product characterization and stability registration data for new drug applications, which involved developing and validating testing protocols, ensuring product delivery, and executing commercial product testing in the U.S. and EU. The study outlines the challenges faced, including the need for rapid ramp-up of personnel and specialized laboratory space for aerosol product characterization. The laboratory's expertise and capacity were critical in managing the aggressive timelines and complex testing requirements. Results indicated successful completion of product testing and timely evaluation of stability data, leading to NDA approval. The partnership allowed the client to focus on data compilation while ensuring high-quality product delivery to patients.