Objectives To study the impact of clinical pharmacist interventions (PIs) on antimicrobial prescriptions in terms of physician acceptance rates, clinical benefits and antimicrobial use/cost outcomes.

Methods This study retrospectively analysed the impact of antimicrobial PIs over a 2-year period (October 2012 to October 2014) in a private non-teaching 164-bed hospital without a formal antimicrobial stewardship programme. Excluded from the study were outpatients and patients admitted to the intensive care unit or the emergency department. The PIs focused on appropriate indication and appropriate dosage; drug adverse events, allergies, intolerance and interactions; sequential therapy; therapeutic de-escalation; excessive duration of treatment and therapeutic drug monitoring. Carbapenems and linezolid were classified as special-vigilance drugs. Amoxicillin-clavulanic, piperacillin-tazobactam and vancomycin were classified as preferred drugs. Clinical benefits evaluated in accordance with internal guidelines, were classified as enhancing appropriate antimicrobial prescription or potentially reducing toxicity. Antimicrobial use and expenditure were compared with that of the previous 2-year period.

Results 386 PIs were implemented in 303 patients. The overall acceptance rate was 83.4%. The acceptance rate for appropriate prescription PIs was significantly lower than for toxicity PIs (73.7% vs 90.9%; p<0.0001). Significant reductions in the use of special-vigilance drugs (from 39.9 (22.2–86.0) to 28.0 (6.0–43.4) defined daily doses (DDD)/1000 patient-days; p=0.0003) were seen and increases in the use of piperacillin-tazobactam (from 13.2 (0–22.9) to 17.2 (6.9–44.8) DDD/1000 patient-days; p=0.007) and of cephalosporins (from 123.5 (61.8–196.6) to 149.1 (80.3–228.2) DDD/1000 patient-days; p=0.027). Overall cost savings were 5.1%.

Conclusions PIs on antimicrobial prescriptions may be effective in enhancing appropriate use of antimicrobials, reducing their toxicity, reducing the use of special-vigilance drugs and reducing overall antimicrobial cost.