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The Prevalence of Polypharmacy and Potential Drug–Drug Interactions among Iranian Cancer Patients: Which Patients were at Risk?

Abstract Introduction Drug–Drug interactions (DDIs) are one of the considerable consequences of polypharmacy. Due to the influence of polypharmacy and drug interactions on cancer treatment and patients` health outcomes, this study aimed to determine the prevalence of polypharmacy and potential DDIs among adult cancer patients in Kerman province, southeast of Iran. Methods In this cross-sectional study, 315 cancer patients who referred to Kerman city oncology clinics were assessed in 2018. Data were collected through face-to-face interviews and medical charts were reviewed. Polypharmacy was defined as the use of at least five drugs simultaneously. Potential DDIs were checked using the “Drugs.com” online database. A bivariable and a multivariable logistic regression were used to determine the associated factors of outcome variables, polypharmacy status, and potential DDI in SPSS software version 23. Results Of 315 cancer patients, 191 patients (60.6%; 95% CI: 54.9, 66) used at least five drugs during chemotherapy courses. The prevalence of potential DDIs was 59.6% (n = 140, 95% confidence interval [CI]: 53.6–66.0. Experience co-morbid diseases (OR: 6.60; 95% CI: 3.82, 11.42; p value ≤ .0001), and positive metastatic status (OR: 2.80; 95% CI: 1.62, 4.82; p value ≤ .0001) could predict the polypharmacy during chemotherapy courses. Patients who suffered gastrointestinal cancers (OR: 5.55; 95% CI: 2.26, 13.62; p value ≤ .0001) and the number of prescribed or Over The Counter (OTC) drugs (OR: 1.29; 95% CI: 1.12, 1.48; p value < .0001) predicted the occurrence of potential DDIs among cancer patients. Conclusions Regarding the high prevalence of polypharmacy and potential drug interactions among Iranian cancer patients during chemotherapy courses, it is advisable for physicians, nurses, and pharmacists to be vigilant to improve prescribing patterns. In addition, with intensive monitoring, alternative treatment strategies can be replaced.