The federal Medicaid system lists prescription drug services as an optional benefit, but each state currently covers a range of medications. [i] There are some vast differences between the states, though, as each system classifies drugs differently. If you need specific medications, make sure to tell your Medicaid enrollment specialist. Your state may also have a prescription drug formulary A formulary is a list of prescription drugs covered by a specific prescription drug plan. that lists all medications covered by its CHIP system.