Background Interferon-free combination direct-acting antivirals (DAAs) regimens have improved tolerability and efficacy for HCV-infected patients but it is necesary to check drug-drug interactions (DDIs) because they have the potential to cause toxicity or loss of efficacy to treat HCV.

Purpose To describe the interactions associated with the use of comedications in patients treated with DAA using a computed-generated alarm tool.

Material and methods Prospective observational study. All HCV-infectect patients initiating DAAs regimens were included. DDIs between DAAs and other comedications were cross-checked using the Farmaweb tool. Farmaweb is a web-based solution that analyses patients’ drug prescription. Clinically relevant DDIs are classified according to the University of Liverpool database as drug combination contraindicated or not recommended (type A), and potential interaction that may require close monitoring or changing dose (type B). The Anatomical Therapeutic Chemical (ATC) groups involved in DDIs were analysed. Data collection was performed between January 2016 to July 2017.

Results Ninety-six potentially relevant interactions were observed in 68 patients. DAAs involved in DDIs were sofosbuvir/ledipasvir (55.2%), paritaprevir/ritonavir, ombitasvir plus dasabuvir (35.4%), grazoprevir/elbasvir (5.2%) and daclatasvir (4.2%). Nine different DDIs were detected for sofosbuvir/ledipasvir, 14 for paritaprevir/ritonavir, ombitasvir plus dasabuvir, five for grazoprevir/elbasvir and four for daclatasvir. The top three medications that can cause clinically relevant DDIs with at least one of the antiviral regimens were proton pump inhibitors (59.3%), HMG CoA reductase inhibitors (18.8%) and antihipertensives (8.3%). The top three of the therapeutic subgroup (second ATC level) were ‘drugs for acid-related disorders’ (A02), ‘lipid modifying agents’ (C10) and ‘calcium channel blockers’ (C08). Only five DDIs (5.2%) were classified as type A. All type A DDIs detected refers to the combination of paritaprevir/ritonavir, ombitasvir plus dasabuvir and statins (simvastatin and atorvastatin).

Conclusion Proton pump inhibitors and statins were frequently involved in DDIs between DAAs and comedications. Drug combination contraindicated or not recommended were scarce and only involved paritaprevir/ritonavir, ombitasvir plus dasabuvir combinations.

Reference and/or Acknowledgements 1. Papatheodoridi Mx, Dalekos GN, Goulis J, Manolakopoulos S, Triantos C, Zachou K, et al. Prioritisation for interferon-free regimens and potential drug interactions of current direct-acting anti-hepatitis C agents in routine clinical practice. Ann Gastroenterol2017;30(5):542–549.

No conflict of interest