Identification and management of contraindicated drug–drug interactions through pharmaceutical care programs: Experience in direct-acting antivirals therapy

Abstract

To investigate the impact of pharmaceutical care programs for the management of contraindicated drug-drug interactions (DDIs) in direct-acting antivirals (DAAs) therapy. A prospective observational study was performed at Dalin Tzu Chi Hospital between January 2018 and December 2019. Pharmacists screened DDIs for all hepatitis C patients before DAA therapy. The study outcome included the frequency of contraindicated DDIs, acceptance rate, and cost avoidance of the pharmaceutical care program. A total of 1053 patients were enrolled in the study, with a mean age of 67.1±11.9 years. Most patients received therapy with sofosbuvir/ledipasvir (37.1%; n=391), elbasvir/grazoprevir (23.8%; n=251), or glecaprevir/pibrentasvir (21.1%; n=222). A total of 796 (75.6%) patients received at least one co-medication, with the average number of co-medications being 5.2 per patient (SD: 4.4/patient). In total, 1356 DDIs were identified, with the average DDIs per patient of 1.3 (SD: 1.7). For patients with contraindicated DDIs (2%, n=102), statins and amiodarone were the most common co-medications. Physicians often accepted pharmacists' recommendations (acceptance rate of 72.5%) or withheld co-medication to avoid severe adverse drug events (ADEs). The estimated cost avoidance of preventable ADEs was USD 14,033 for contraindicated DDIs with pharmaceutical care programs. The implementation of pharmaceutical care programs in DAA therapy provides a favorable outcome and substantial cost avoidance.