A computer system and method manages the disbursement and replacement of medication units to patients. Medication units disbursed to qualified patients under qualified discount plans are replaced by replenishment. Computer systems implementing traditional replenishment, cached replenishment, and prepurchased replenishment are disclosed. The computer system and method monitors medication units disbursed to patients by a pharmacy and tracks the amount of medication units disbursed to qualified patients of health care providers qualified under a discount program. When the amount of disbursed medication units reaches a threshold, replacement medication units are ordered. The medication units disbursed to non-qualified patients are replaced through restocking and the medication units disbursed under a qualified discount program are replaced through traditional replenishment, cached replenishment, and/or prepurchased replenishment.