How does the 340B program affect manufacturer economics?

Covered entities purchase outpatient drugs at 340B ceiling price (WAC minus minimum 23.1% for brands, 13% for generics). Contract pharmacy expansion has grown 340B purchases to over $53B annually. Manufacturers face double-discount exposure when 340B claims also generate Medicaid rebates. Several manufacturers have restricted 340B contract pharmacy access, triggering HRSA enforcement.