The Prevalence of Drug–drug Interactions in Cancer Therapy and the Clinical Outcomes

Background: When a patient concomitantly uses two or more drugs, a drug-drug interaction (DDI) may occur, and patients with cancer are at high risk of DDIs because they commonly receive multiple medications. However, data on the prevalence of DDIs are scarce, especially in Saudi Arabia. Objective: Our aim was to evaluate the occurrence of DDIs in patients with cancer and identify risk factors for these DDIs and the clinical outcomes. Method: A retrospective cross-sectional study was conducted in KFMC. Data were collected from the medical records and phone calls, and the patient's drugs were screened for interactions using Micromedex and Lexi-Comp. The data were statistically analysed using IBM SPSS version 24 statistical program. Results: In 72 patients (mean age of 47 years; 11 medications), the prevalence of DDIs was 60 %, and 2 potential DDIs were identified. According to Lexi-Comp, 137 (51.8 %) were categorized as pharmacodynamics interactions. In Micromedex, 94 potential DDIs were identified, 68.1 % were categorized as pharmacokinetic interactions, the comparison between the interaction of Lexi-Comp and Micromedex for 9 drugs. Eight drug pairs showed statistically significant difference in category of interaction (P < 0.05). Six pair of drugs showed statistically significant difference in mechanism of action (p < 0.05). Number of drugs was reported as significant risk factor (p = 0.007), type of treatment such as chemotherapy (p = 0.0000) and inpatient admission in terms of length of stay in hospital was also found significant risk factor (p = 0.031). Conclusion: To prevent DDIs, Physicians and pharmacists should be more aware of these potential interactions to prevent DDIs.