Roles and perceived responsibilities of investigators and pharmacists in the monitoring of drug-drug interactions in clinical trials - a mixed methods study

Purpose To explore the roles and perceived responsibilities of clinical investigators and pharmacists in the monitoring of drug-drug interactions (DDIs) between study medication and concomitant medication in clinical trials. Secondly, sharing of information on study medication treatment with community and hospital outpatient pharmacies was investigated. Methods We performed a mixed methods study comprising qualitative semi-structured interviews with clinical investigators and online questionnaires among hospital pharmacists and community and hospital outpatient pharmacists. Results Interviews with investigators show they generally consider the current way of DDI monitoring in trials to be adequate. However, they emphasized the need to better define responsibilities and further digitalize monitoring. A total of 43 responses were received from hospital pharmacists (response rate: 62.3% [43/69]). One response was excluded because the hospital did not dispense any study medication. Approximately half of the hospital pharmacists (45.2%, [19/42]) routinely conduct DDI monitoring with concomitant medication when dispensing study medication for patients enrolled in clinical trials. A total of 49 responses were received from community and outpatient pharmacists. Most of the responding pharmacists (44/49 [89.8%]) had been informed about study medication use by a patient in the preceding year. Community and outpatient pharmacists however noted that background information on potential DDIs with study medication is often lacking (19/44 [43.2%]). Conclusion Our study highlights critical gaps in the management of DDIs related to the use of study medication with concomitant medication. Clearer allocation of responsibilities, improved digital integration, and sharing of study medication related information may strengthen clinical trial data validity and improve patient safety.