NSAID dosing schedule and compliance.

prescriber antagonism has been encountered. Cost savings for one year have been approximately $55 000. Based on acceptance by prescribers and success of the above intervention, usage reviews have been conducted to identify other drugprescribing problems that may be amenable to intervention. In 1986-87, over $117000 was spent on parenteral metronidazole at this institution. Metronidazole also possesses characteristics that permit extended (12-hour) intervals of administration.' A review of 216 written inpatient orders revealed that 94 percent of treatment courses during a 14-weekperiod involved dosage intervals of eight hours or less. Only 4 percent of treatment courses involved 12-hour dosage intervals. In June 1987, an identical two-stage intervention was used to convert metronidazole from q8h to ql2h regimens. Again, both stages had a significant impact on prescribing ~abit~. Aft.er the persuasive stage was initiated, 27 percent of all written mpatient orders were for 12-hour dosage intervals; this increased to an average of 94 percent for 18weeks following implementation of the second sta~e of the intervention. An average of 59 percent of total orders were written by the prescriber for extended intervals. The bal~nce were s~cc~ss­ fully converted by therapeutic interchange. Contmuous momto~m.g shows no deviation from the above trends. To our knowledge, this IS the first report of such an intervention to increase metronidazole dosage intervals to 12 hours. Cost savings are estimated to be $24 000 in the first year of the program. The two-stage intervention was implemented in October 1986 to convert tobramycin written inpatient orders to gentamicin (except in critical care areas where pseudomonal infections warrant tobramycin usage). Annual cost savings achieved as a result of this inter~ention have been $34 000. Clindamycin will be added to the program m early 1988. This is another antibiotic for which extended (eight-hour) dosage intervals are possible and can result in a savings of $30 000 per year at this hospital. The design of this program does not permit us to evaluate whether physicians modified their prescribing behavior as a consequence of the rationale supporting extended interval dosing or in anticipation of the therapeutic interchange stage. However, the fact that prescribers had the option of requesting no substitution and did so infrequently suggests that the rationale was generally accepted and extended-interval prescribing was adopted. Perhaps prescribers would have resisted the change if therapeutic interchange had been initiated without a preceding persuasive stage. Such other factors as peer-group endorsement and the presence of preprinted orders in the patient's health record when an interchange was required may have increased compliance. Our assessments were not designed to determine the impact of each factor, but to measure the overall effectiveness of the two stages of intervention. In our institution, the combined effect of persuasive and power strategies has proved successful. Continued prescriber acceptance is demonstrated by the percentage of orders in which no interchange is required to comply with appropriate use guidelines, and by minimal use of the' 'no substitute" clause. This two-stage intervention can be used to effect virtually any modification in prescribing trends deemed appropriate by an institution. It is especially well suited for hospitals with a transient prescribing population for whom episodic forms of intervention are not effective.