42 CFR §409.25

1. (a)Drugs and biologicals. Except as specified in paragraph (b) of this section, Medicare pays for drugs and biologicals as posthospital SNF care only if—
   1. (1)They represent a cost to the facility;
   2. (2)They are ordinarily furnished by the facility for the care and treatment of inpatients; and
   3. (3)They are furnished to an inpatient for use in the facility.
2. (b)Exception. Medicare pays for a limited supply of drugs for use outside the facility if it is medically necessary to facilitate the beneficiary's departure from the facility and required until he or she can obtain a continuing supply.
3. (c)Supplies, appliances, and equipment. Except as specified in paragraph (d) of this section, Medicare pays for supplies, appliances, and equipment as posthospital SNF care only if they are—
   1. (1)Ordinarily furnished by the facility to inpatients; and
   2. (2)Furnished to inpatients for use in the facility.
4. (d)Exception. Medicare pays for items to be used after the individual leaves the facility if—
   1. (1)The item is one that the beneficiary must continue to use after leaving, such as a leg brace; or
   2. (2)The item is necessary to permit or facilitate the beneficiary's departure from the facility and is required until he or she can obtain a continuing supply, for example, sterile dressings.