Tehran University of Medical Sciences Journal of Pharmaceutical Care 2322-4630 13 4 2025 12 31 294 301 Maryam Taghizadeh-Ghehi Research Center for Rational Use of Drugs, Tehran University of Medical Sciences, Tehran, Iran Fatemeh Farahani Tehran University of Medical Sciences Hassan Torkamandi Bayshore Specialty Rx, Medical Practices, Mississauga, Ontario, Canada. Mehrdad Assarian Tehran University of Medical Sciences Samira Chaibakhsh Cardiovascular Epidemiology Research Center, Rajaie Cardiovascular Medical and Research Institute, Iran University of Medical Sciences, Tehran, Iran. Mohammad Reza Javadi Tehran University of Medical Sciences 2026 07 14 2026 07 14 Background: The high prevalence of resistance to broad-spectrum antibiotics in the hospital setting is a challenge worldwide. Inappropriate use of carbapenems has led to growing antimicrobial resistance, specifically in gram-negative pathogens. Evidence suggested that interventions might improve the appropriate use of carbapenems in hospitals. Therefore, we aimed to compare the appropriate use of carbapenems before and after guideline implementation and to investigate consumption trends over 8 years, following restriction policies. Methods: This quasi-experimental study was conducted in a tertiary referral teaching hospital. Before and after the implementation of the carbapenem use guideline in the hospital, utilization of imipenem and meropenem was evaluated with respect to the appropriateness of indication, initial dose, maintenance dose, and obtaining cultures. Annual consumption of carbapenems in terms of Defined Daily Doses (DDDs) per 100 Occupied Bed-Days (OBDs) was estimated in the hospital from 2014 to 2021. Results: The frequency of generally appropriate orders increased from 31.6% at baseline to 38% after the primary intervention (P=0.057). The number of cases with carbapenem use for more than 5 days without obtaining cultures decreased significantly in the second evaluation phase (from 15.8% to 8.1%, P=0.001). Despite fluctuations and a non-steady trend, carbapenem consumption increased from 39.30 to 71.37 DDDs/100 OBDs over 8 years with a statistically significant trend (p < 0.001, R² = 0.93). Conclusion: The rising carbapenem consumption rate was slowed down following the interventions. Additionally, our study demonstrated that guideline implementation improved the appropriate choice of carbapenem and the timely obtaining of cultures. However, the practice change was temporary and limited before the commencement of the restriction policy and ASP.  Prospective audit and feedback might be necessary to achieve sustainable changes in the appropriate use of carbapenem in hospitals. https://jpc.tums.ac.ir/index.php/jpc/article/view/948 https://jpc.tums.ac.ir/index.php/jpc/article/download/948/440