This study compares the expected occurrence of contraindicated drug-drug interactions (XDDIs) when simeprevir (SIM)- or sofosbuvir (SOF)-containing therapy is added to medication profiles of patients with hepatitis C (HCV) monoinfection to quantify, in relative terms, the population-based risk of XDDIs. Second, this study identified the predictors of XDDIs when HCV therapies are added to medication profiles. A cross-sectional study was performed among Veterans' Affairs patients. Inclusion criteria were: (1) age ≥18 years, (2) HCV infection, and (3) availability of a medication list. Patients with human immunodeficiency virus were excluded. Demographics, comorbidities, year of HCV diagnosis, and most recent medication list were collected from medical records. The primary outcome was the presence of XDDIs involving HCV therapy and the medications in the patient's home medication list after the addition of either SIM- or SOF-containing regimens. To define XDDIs, Lexi-Interact drug interaction software was used. 4,251 patients were included. The prevalence of XDDIs involving SIM- or SOF-containing therapy were 12.6% and 4.7% (p < 0.001), respectively. In multivariable analyses examining the predictors of XDDIs involving SIM-containing therapy, the only medication-related predictor was use of ≥6 home medications (odds ratio OR 4.58, 95% confidence interval CI 3.54-5.20, p < 0.001). Similarly, use of ≥6 home medications was also the only variable associated with an increased probability of XDDI involving SOF-containing therapy (OR 3.83, 95% CI 2.57-5.70, p < 0.001). Sofosbuvir-containing therapy had a lower frequency of XDDIs than SIM-containing therapy. Polypharmacy with various classes of home medications predicted XDDIs involving SIM- or SOF-containing therapy.

Background: Among patients with HIV and hepatitis C (HCV) coinfection, drug-drug interactions involving nonstructural protein 3/4 (NS3/4A) serine protease inhibitors for HCV infection are an important concern because these drugs affect cytochrome P450 metabolism and p-glycoprotein transporters. Objectives: The primary objective was to determine the prevalence of clinically significant drug-drug interactions (CSDDIs) in HIV/HCV coinfected patients if telaprevir-based HCV therapy is added to patients' medication regimens. Secondary objectives were to identify antiretroviral therapy (ART) regimens associated with the lowest risk of CSDDI and determine the clinical risk factors. Methods: A cross-sectional study was performed among adult HIV/HCV coinfected patients. Demographics, comorbidities, social history, and medication lists were extracted from medical records. For each patient, CSDDIs were identified by entering all medications and pegylated interferon, ribavirin, and telaprevir into Lexi-Interact drug interaction software. The number and nature of CSDDIs were recorded before and after addition of telaprevir-based therapy. Results: There were 335 patients included. Prior to the addition of telaprevir-based HCV therapy, there was a high frequency (82.1%) of any CSDDI. After the addition of telaprevir-based HCV therapy, the frequency of any CSDDI increased to 97% (P < .001). Contraindicated interactions rose from 20.0% to 38.2% of patients after addition of telaprevir-based therapy. Use of ≥10 non-HIV medications, dyslipidemia, and HIV protease inhibitors were independently associated with the occurrence of a contraindicated interaction. Conclusions: Clinicians considering initiating telaprevir in HIV/HCV coinfected patients should be vigilant of drug-drug interactions, particularly among patients with dyslipidemia, those using ≥10 non-HIV medications, and those using HIV protease inhibitors.