Supply Chain Security and Pharmaceutical Authentication Act of 2021 This bill modifies the application of requirements for drug packaging to include certain information, such as the product's lot number and expiration date. Under the bill, the requirements shall apply to the packaging of the smallest or individual solid oral dosage form of the product. Currently, such requirements apply to the smallest container (which might contain multiple dosages) of the product that is intended for individual sale to a dispenser, such as a pharmacy.