To assess the long-term impact of a therapeutic interchange program on
the use of target antimicrobial drugs, we conducted a retrospective s
tudy of target drug utilization at our institution-a 1,000-bed Canadia
n tertiary care teaching hospital. Data were assessed to determine tar
get drug utilization, incidence of therapeutic interchanges, and patie
nt-target drug exposures. Results showed that the incidence of therape
utic interchanges per patient-target drug exposure decreased from a me
an of 23% to 2%, resulting in a total net savings for the target drugs
of approximately $1.07 million (Canadian) over 6 years. Prescriber ac
ceptance and low manpower requirements combined to make this a useful
method of altering prescribing patterns and reducing drug and drug del
ivery costs.