Impact of a two-stage intervention program on cefazolin usage at a major teaching hospital.

To reduce antimicrobial drug costs associated with the administration of cefazolin, a two-stage therapeutic intervention--employing persuasive (informational) and power (therapeutic interchange) strategies--was initiated at this 1,000-bed major Canadian teaching hospital. The target of the intervention was to extend the dosage interval of cefazolin to q8h. During a 12-week preimplementation period, 32% of orders specified 8-hour dosage intervals. This percentage increased to 58% after the 3-week, initial informational stage of the intervention. When therapeutic interchange was employed, the percentage of orders for extended intervals rose to an average of 97% over a 32-week postimplementation period. An estimated annual cost savings of $58,000 resulted from this intervention. Manpower requirements to implement and maintain this program were minimal and prescriber antagonism was not encountered.