Tehran University of Medical Sciences Journal of Pharmaceutical Care 2322-4630 8 1 2020 03 24 16 22 Mojtaba Shafiekhani Department of Clinical Pharmacy, Faculty of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran. Sara Tarighati Department of Clinical Pharmacy, Faculty of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran. Ehsan Mirzaei Department of Clinical Pharmacy, Faculty of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran. Soha Namazi Department of Clinical Pharmacy, School of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran. 2019 10 13 2020 01 15 Background: Kidney transplant patients usually take a combination of medications after transplantation; hence, medication safety becomes an important issue in order to maintain the new organ working properly. To evaluate the incidence and risk factors associated with potential drug-drug interactions (pDDIs) in hospitalized patients in Nephrology and Post-transplant wards to improve clinical management of pDDIs by a clinical pharmacist. Methods: In this cross-sectional study, patients in Nephrology and Post-transplant wards were screened for pDDIs, using the interaction screening program Lexi-comp resource®. After evaluating the detected pDDIs for clinical relevance, the intervention was performed through physicians or nurses for type D and X drug interactions. Intervention feedback, implemented recommendations, and any probable adverse drug reactions were documented. Results: During the study, 399 patients (239 in nephrology and 160 in post-transplant wards) plus 6105 drug orders were evaluated, and a total of 3263 DDIs were identified; of them, 827 (23.5%) were determined to be D and X classifications, and a total of 89.97% of all hospitalized cases had at least 1 pDDIs. Factors that had the greatest influence on pDDI incidence included the number of drugs and the admitted wards. Patients in the post-transplant ward experienced 2.3 times more DDIs than those in the nephrology ward. In total, 78% of class X and D DDIs required intervention, of which 75% were accepted and implemented by the physicians and nurses. Conclusion: Clinically relevant pDDIs are common in patients in Nephrology and Post-transplant wards, and pharmacists play a critical role in detecting and managing this medical problem in hospitalized patients. https://jpc.tums.ac.ir/index.php/jpc/article/view/290