Abstract
Objective: The main objective of this study was to evaluate therapeutic drug monitoring (TDM) services for antibiotics and investigate the association between non-adherence to TDM guidelines and development of nephrotoxicity. Materials and methods: This retrospective study was conducted using electronic health records of hospitalized patients who received antibiotics for which TDM was requested over a 1-year period. Adherence to TDM guidelines was measured by reviewing appropriate indications, sampling times, result reporting, and clinical pharmacist interventions. Results: A total of 1,179 patients (65% males), for whom TDM was requested during 2017 were included. Upon an assessment of the appropriateness of sampling times, we found that similar to 15% of samples were drawn at the wrong time, and in over 46% of the cases, TDM service was inconsistent with guidelines. Further, although physicians accepted the majority of pharmacists' interventions related to the TDM service, the pharmacist did not provide any recommendation in more than one-third of the cases. Nephrotoxicity was the most common adverse reaction and was observed in 19.5% of the patients. Furthermore, we found a significant correlation between nephrotoxicity and non-adherence to TDM guidelines (OR = 1.47; p = 0.014). Our study shows that adherence to the guidelines and implementation of an appropriate and effective TDM service for antibiotics increases the number of patients with adequate plasma levels, optimizes clinical outcomes, and minimizes toxicities. Moreover, there was a strong association between non-adherence to the TDM guidelines and development of nephrotoxicity. Conclusion: The findings suggest that adherence to TDM guidelines not only improves clinical practice but also contributes to the reduction of the cost associated with the development of nephrotoxicity.