A CMS Memorandum (29Kb PDF file) explains how Part D plans must cover all or substantially all drugs in six categories:
These CMS documents (45Kb PDF file) explain which drugs are covered by Medicare Part B and which by Part D.
In June 2007, CMS updated its Guidance (235Kb PDF file) that describes how the Best Available Evidence Rule works for people with Medicare and Medicaid (duals). The Best Available Evidence policy was reiterated by CMS in November 2007.
Niacin is a vitamin and was therefore originally determined by the Centers for Medicare & Medicaid Services (CMS) to be excluded from Part D coverage. Niacin, however, in certain doses is an important therapeutic tool in the treatment of high cholesterol.
CMS accordingly revised its policy (11Kb PDF file) to allow coverage of Niacin in therapeutic doses when prescribed for the reduction of high cholesterol.
This CMS Provider Inquiry Assistance document, dated July 10, 2007, part of the CMS Medicare Learning Network for Medicare providers, describes Medicare Part D coverage for vaccines starting in 2008.