When sourcing hormone drugs, the most critical requirement is GMP (Good Manufacturing Practice) certification, which ensures products are consistently produced and controlled according to quality standards. Additionally, you should verify the CEP (Certificate of Suitability to the Monographs of the European Pharmacopoeia) or a Drug Master File (DMF) registration. For the product itself, ensure it complies with international pharmacopoeia standards such as USP (United States Pharmacopeia), BP (British Pharmacopeia), or EP (European Pharmacopeia). Always request a Certificate of Analysis (COA) for every batch to verify purity, potency, and the absence of impurities.