Antimicrobial stewardship programs (ASPs) are essential to improve the quality of antibiotic use and to contain bacterial resistance. Clinical pharmacy plays a strategic role in this process through prescription validation, monitoring of antimicrobial use, and targeted interventions. This study aimed to evaluate the impact of implementing an ASP with active participation of the clinical pharmacy team on prescription quality indicators and the consumption of restricted antimicrobials.

This was a quasi-experimental study with interrupted time-series analysis covering the period from February (ASP initiation) to May. The variables analyzed were: (1) overall prescription compliance, (2) compliance regarding treatment duration, (3) compliance regarding clinical indication, and (4) monthly consumption (DDD) of two restricted antimicrobials (vancomycin and meropenem). The Friedman test was applied to compare compliance proportions across the four months analyzed, with a significance level of 5%.

Overall prescription compliance increased from 58% in February to 76%, 77%, and 71% in March, April, and May, respectively (p = 0.046). Compliance with treatment duration rose from 73% to 91%, 90%, and 96% (p = 0.028). Compliance with indication improved from 77% to 94%, 91%, and 88% (p = 0.034). Vancomycin consumption peaked in March (529 DDD) and progressively decreased thereafter (237 in April and 105 in May). Meropenem followed a similar pattern, with 329 DDD in March, decreasing to 271 and 118 in the following months. These reductions coincided with reinforcement of ASP activities in critical care units.

Implementation of the ASP with integrated participation of the clinical pharmacy team led to significant improvements in prescription indicators and a consistent reduction in the use of restricted antimicrobials. The service includes a clinical pharmacy resident who conducts daily prescription audits in collaboration with infection control specialists and provides in-person interventions, particularly in the ICU. These preliminary results suggest that structured clinical pharmacy involvement can meaningfully enhance program effectiveness, reinforcing its role as an essential component of stewardship strategies.