Limited drug-drug interaction of elbasvir/grazoprevir for chronic hepatitis C.

<bold>Background/purpose: </bold>The assessment of drug-drug interaction (DDI) is important not only for safety but also for maintaining the efficacy of direct acting antivirals in chronic hepatitis C (CHC). This study aims to evaluate DDI before and during elbasvir/grazoprevir (EBR/GZR) treatment.<bold>Methods: </bold>CHC patients who treated with EBR/GZR in five hospitals were enrolled. The patients' demographic data, comorbidities, concomitant medications taken before and during EBR/GZR were recorded. DDI was evaluated using a tool from the HEP Drug Interactions (www.hep-druginteractions.org) website. In addition to the evaluation of DDI for EBR/GZR, the virtual DDI of ledipasvir/sofosbuvir (LDV/SOF), sofosbuvir/velpatasvir (SOF/VEL) and glecaprevir/pibrentasvir (GLE/PIB) were evaluated. Degrees of DDI were classified as "do not co-administer", "potential interaction", and "potentially weak interaction".<bold>Results: </bold>A total of 460 patients were enrolled. At baseline, 80.1% of patients had one or more comorbidities and 72.8% took one or more medications. Cardiovascular diseases (43.9%), gastrointestinal diseases (37.4%), and metabolic diseases (36.7%) were the three most common comorbidities. The prevalence of DDI before EBR/GZR treatment was 12.8% (59 patients). Among the same population, the prevalence of virtual DDI of SOF/VEL, GLE/PIB, and LDV/SOF were 38.5% (179 patients), 48.8% (220 patients), and 57.0% (262 patients), respectively. During EBR/GZR treatment, 167 patients (36.3%) took newly prescribed medications. One patient (0.2%) and seven patients (1/5%) exhibited do-not-co-administer and potential interaction with EBR/GZR, respectively.<bold>Conclusion: </bold>DDI was limited in treatment with EBR/GZR. DDI can occur upon the administering of a new medication during antiviral treatment and attention should be paid to it.<bold>Trial Registration Number: </bold>NCT03706222. [ABSTRACT FROM AUTHOR]