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

Background/purpose: To investigate the impact of pharmaceutical care programs for the management of contraindicated drug-drug interactions (DDIs) in direct-acting antivirals (DAAs) therapy.

Methods: 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.

Results: 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.

Conclusion: The implementation of pharmaceutical care programs in DAA therapy provides a favorable outcome and substantial cost avoidance.