Where does NADAC data come from and how reliable is it?

NADAC (National Average Drug Acquisition Cost) is surveyed weekly by CMS contractor Myers and Stauffer from a sample of 2,500+ retail pharmacies. It reflects actual pharmacy purchase prices, not list prices. NADAC is considered the most accurate publicly available drug pricing benchmark, though it lags real-time market changes by 1-2 weeks and does not capture hospital or specialty pharmacy pricing.