Avoidance of drug interactions with hepatitis C treatment: Evaluation of pharmacist interventions in the specialty setting.

Objectives: Direct-acting antiviral (DAA) therapy is currently recommended for most patients chronically infected with the hepatitis C virus (HCV) by the American Association for the Study of Liver Diseases/Infectious Diseases Society of America guidelines. DAAs have significant drug interaction potential, which can lead to treatment failure and adverse drug events. The primary goal of this study is to report the number and nature of interventions made by pharmacists regarding drug interactions in patients using DAA therapy and to estimate the cost avoidance of averting potential DAA treatment failures.
Methods: The patients in this cohort were identified through the pharmacy's electronic medical record if they were at least 18 years old while having filled a prescription for a DAA between 6/1/2019 and 06/01/2020. Data for this study were collected retrospectively using a report generated by the pharmacy electronic medical record and through manual chart review. Calculations for cost avoidance associated with prevention of DAA treatment failures are estimations based on the current average wholesale price (AWP) and wholesale acquisition cost (WAC) pricing.
Results: A total of 808 patients were identified as filling a prescription for HCV treatment during the measurement period. Average patient age was 49.8 years, and 60.5% of patients were male. A total of 267 patients (33%) were identified as having at least one drug-drug or drug-disease interaction. Of the 304 potential interactions identified, 132 drug interactions (43.9%) could have led to treatment failure and 172 (56%) could have resulted in adverse events. The estimated cost avoidance for interventions made by clinical pharmacists to avert treatment failures (132 regimens) was $387,968 and $323,306 using AWP and WAC pricing, respectively.
Conclusion: Pharmacists in the specialty pharmacy setting are essential for the evaluation of potential drug and disease state interactions with HCV therapies. These interventions potentially averted treatment failures and adverse drug events.
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