December 1st 2008In 2003, the Canadian Forces (CF) drug benefit plan used preferential listing to control costs associated with proton pump inhibitors (PPIs); however, significant expenditures for nonbenefit PPIs continued. A database review was thus conducted to explain this anomalous usage pattern. This study provides further information regarding the effectiveness of preferred listing as a cost-saving measure, noting that adherence to such policies may be less than projected.