; or (BB) if the information specified in subitem (AA) is not available, the most recent National Average Drug Acquisition Cost for such drug for applicable non-retail pharmacies. (III) Definition of essential retail pharmacy In this clause, the term essential retail pharmacy means, with respect to a plan year, a retail pharmacy that— (aa) is not an affiliate of a pharmacy benefit manager or PDP sponsor; (bb) is located in a medically underserved area (as designated pursuant to section 330(b)(3)(A) of the Public Health Service Act)