patients of the covered entity, to administer contracted pharmacy services, or to provide any other service related to the drug discount program under this section, the remuneration for which is based in whole or in part on the volume of dispensed covered outpatient drugs subject to an agreement under this section, such covered entity shall— (A) have a contractual agreement in place between the covered entity and each contracted entity, including with each location of a pharmacy contracted to dispense covered outpatient drugs subject to an agreement under this section to patients (as so defined) of the covered entity, which shall specify that the contracted entity shall adhere to all requirements of the drug discount program under this section, but that ultimate responsibility for program compliance and oversight of compliance by each contracted entity shall remain with the covered entity and that all covered outpatient drugs subject to an agreement under this section shall be purchased by the covered entity