Drug-drug interactions (DDIs) are common in patients taking hepatitis C virus (HCV) medications, and the involvement of a clinical pharmacist could benefit the interdisciplinary hepatology team, researchers reported in the World Journal of Gastroenterology.

Jacob A. Langness, from the University of Colorado Hospital in Aurora, and colleagues sought to quantify DDI use in patients who were prescribed HCV treatment, interventions that were conducted, and the time required to complete these steps. A clinical pharmacist screened for DDIs in patients who were prescribed direct acting antiviral (DAA) HCV treatment between November 2013 and July 2015 at the University of Colorado Hepatology Clinic. Treatment included ledipasvir/sofosbuvir (LDV/SOF), paritaprevir/ritonavir/ombitasvir/dasabuvir (OBV/PTV/r + DSV), simeprevir/sofosbuvir (SIM/SOF), and sofosbuvir/ribavirin (SOF/RBV). The researchers then conducted a retrospective analysis to review the work performed by the clinical pharmacist.

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A total of 664 patients (83.4% Caucasian; 57% male; average age, 56.7 years) were identified — 369 were taking LDV/SOF, 48 were taking OBV/PTV/r + DSV, 114 were taking SIM/SOF, and 133 were taking SOF/RBV. The majority (51.5%) of patients had cirrhosis.

The researchers reviewed 5,217 medications (7.86 medications per patient), and 781 interactions were identified (1.18 interactions per patient). The number of interactions was the lowest for patients in the SOF/RBV group (0.17 interactions per patient) and highest for the OBV/PTV/r + DSV group (2.48 interactions per patient). The LDV/SOF and SIM/SOF groups had a comparable number of interactions (1.28 and 1.48 interactions per patient, respectively).

Gastric acid modifiers and vitamin/herbal supplements were common causes of interactions with LDV/SOF. Hypertensive agents, analgesics, and psychiatric medications were frequent causes of interactions with OBV/PTV/r + DSV and SIM/SOF. For managing these interactions, the pharmacists most frequently recommended discontinuing the medication (28.9%), increasing monitoring for toxicities (24.1%), or separating administration times (18.2%). The pharmacist’s chart review for each patient usually took about 30 minutes, with additional time needed for patients with more complex conditions.

“DDIs are common in patients prescribed HCV medications, and the involvement of a clinical pharmacist can be beneficial to the interdisciplinary hepatology team,” stated the researchers. “Identification and management of DDIs is resource intensive and requires medication adjustments and increased monitoring. Clinical pharmacists can encourage preventive measures on reducing HCV transmission, increase education adherence, assist in initiating HCV treatment, assist in monitoring clinical and adverse effects, and facilitate medication acquisition.”


  1. Langness JA, Nguyen M, Wieland A, Everson GT, and Kiser JJ. Optimizing hepatitis C virus treatment through pharmacist interventions: Identification and management of drug-drug interactions. World J Gastroenterol. 2017; 23(9):1618–1626. doi:10.3748/wjg.v23.i9.1618