 In addition, in many states, state pharmaceutical assistance programs provide similar protection in the gap to middle-income seniors and allow beneficiaries to change plans one other time during the year in addition to the annual enrollment/re-enrollment period.While CMS does not have an established formulary, Part D drug coverage excludes drugs not approved by the Food and Drug Administration, those prescribed for off-label use, drugs not available by prescription for purchase in the United States, and drugs for which payments would be available under Part B.Part D coverage excludes drugs or classes of drugs that may be excluded from Medicaid coverage.