The Obama administration says it is concerned that some states are restricting access by low-income people to costly, revolutionary drugs for a liver-wasting disease called hepatitis C. In a notice to state Medicaid directors Thursday, the government reminded states of their legal obligations to cover prescription medications for the poor. The federal Centers for Medicare and Medicaid Services says some states may be “unreasonably” restricting access to the new hepatitis C cures that can cost more than $1,000 a pill.