Market power and state costs of HIV/AIDS drugs.

We examine whether U.S. states can use their market power to reduce the costs of supplying prescription drugs to uninsured and underinsured persons with HIV through a public program, the AIDS Drug Assistance Program (ADAP). Among states that purchase drugs from manufacturers and distribute them directly to clients, those that purchase a greater volume pay lower average costs per prescription. Among states depending on retail pharmacies to distribute drugs and then claiming rebates from manufacturers, those that contract with smaller numbers of pharmacy networks have lower average costs. Average costs per prescription do not differ between the two purchase methods.