The SUSTAIN 340B Act aims to enhance the integrity and accountability of the 340B drug discount program, which provides discounted medications to healthcare providers serving low-income and underserved populations. The legislation focuses on improving compliance, preventing misuse of discounts, and ensuring that the program effectively supports healthcare providers and their patients. Key provisions include allowing covered entities, such as hospitals and clinics, to use both their own pharmacies and contract pharmacies for dispensing discounted medications.