Prevalence of potential drug-drug interactions in breast cancer patients and determination of their risk factors

Breast cancer patients use numerous medications, which include cytotoxic chemotherapy drugs, hormonal agents and supportive medication, so they are more vulnerable to potential adverse drug interactions. This study aimed to evaluate frequency, severity, clinical importance and risk factors responsible for the Drug-drug interactions (DDIs) in a cohort of patients suffering from breast cancer. Data was obtained from 150 patients in the oncology ward (both inpatient and outpatient) with a confirmed diagnosis of breast cancer and currently receiving standard breast cancer-directed treatment. The data was recorded into a pre-designed form specifically made for this study through individual patient interviews and by reviewing the detailed medical chart records of the patients. DDIs were identified by using drug interaction software such as Medscape mobile application and Micromedex version 2. The results of this study showed that all patients were female. The mean numbers of drugs that patients used were 7. Potential drug interactions were identified in 92% of the patients. When drug groups were overviewed, 32% of interactions were between anti neoplastic drugs, 62.9% interactions were between the anti neoplastic agent and supportive care drugs and 5% of them were between anti-cancer drugs and drugs used to treat comorbidities. Major DDIs were found in 62.2% of patients, 25.3% of DDIs were moderate and 12.4% were minor. The number of drugs, comorbid diseases, and selection of chemo protocols were the risk factors for drug interactions. Most of the DDIs found in breast cancer therapy may have adverse consequences on patient health and therapeutic outcomes. Therefore, health care professionals should review the medication regimen of patients with breast cancer before starting any chemotherapy treatment.