Regulatory authorities are governmental bodies empowered to oversee clinical research and approve drugs, biological products, and medical devices for commercial distribution within their respective jurisdictions. These agencies establish and enforce the rules governing clinical trials, review applications for marketing authorization, and conduct inspections to verify compliance with applicable requirements. Their decisions determine whether new therapies can be made available to patients in their countries.

Major regulatory authorities whose requirements significantly influence global drug development include the United States Food and Drug Administration (FDA), the European Medicines Agency (EMA), Japan's Pharmaceuticals and Medical Devices Agency (PMDA), and Health Canada. Each authority has its own specific requirements, though international harmonization efforts through ICH have aligned many technical standards. Sponsors conducting multinational trials must ensure compliance with the requirements of each authority in countries where they intend to seek marketing approval.

Interactions with regulatory authorities occur throughout the drug development lifecycle. Before initiating clinical trials, sponsors typically submit investigational applications providing preclinical data supporting the proposed human studies. During trials, sponsors submit safety reports and may request guidance through formal meetings. Following trial completion, comprehensive marketing applications present the complete evidence package supporting approval. Post-approval, sponsors must fulfill ongoing reporting requirements and may be subject to inspections verifying continued compliance.