(P39) Retrospective analysis of co-medication patterns in patients treated for HCV, and potential DDIs with DAAs, in Norway during 2014-2018 using the NorPD.
Karlsen LN , Ulstein K , Mikkelsen Y , Rosseland CM , Singh R , Dalgard O 
 Department of Medicine, Stavanger University Hospital, Stavanger, Norway.  Hepatitt C-klinikken, Prindsen mottakssenter, Municipality of Oslo, Norway  LINK Medical, Oslo, Norway  MSD, Norway  Department of Infectious Diseases, Akershus University Hospital, Lørenskog, Norway; Institute of Clinical Medicine, University of Oslo, Oslo, Norway
The potential for drug-drug interactions (DDIs) is an important consideration for HCV-infected individuals with concomitant medications. The aim of this study was to describe the co-administration of medication during HCV treatment, and to assess potential DDIs (pDDIs) with currently approved HCV treatments.
The study is a retrospective cohort study using population-based data from patients who were prescribed an antiviral for treating HCV infection in the period 2012-2018. The data was sourced from the Norwegian Prescription Database. Here, data from the era of second-generation direct acting antivirals (DAAs) (2014-2018) are presented. A list of currently available DAA regimens was compiled and cross-checked for pDDIs with used co-medication using the data-base of the University of Liverpool, and DDIs are described as either 1) potential weak interaction, 2) potential interaction and 3) do not co-administer.
We included 7531 patients who had been dispensed at least one course of HCV treatment. The median age was 51 years (18-75+) and 64% were male. HIV coinfection was present in 303 patients (4%). 94 % of HCV patients received comedications. The most common comedications were oxazepam in 54% (4072 patients), followed by buprenorphine in 24% (1822 patients), and methadone in 17% (1269 patients). In this cohort, 1439 (19.6%), 2717 (37.0%) and 1070 (14.6%) patients were prescribed at least one comedication with a DDI in the grade 1-3 categories, respectively while on HCV treatment. When cross-checking with the Liverpool data-base using the 80% most prescribed comedications from 2014-2018 at least one pDDI of grade 2 or 3, was observed in 15.5% and 0.2% of patients for ledipasvir/sofosbuvir, 29.9% and 5.5% of patients for parietaprevir/ritonavir/ombitasvir/dasabuvir, 29.9% and 5.5% of patients for parietaprevir/ritonavir/ombitasvir, 13.6% and 0.1% of patients for elbasvir/grazoprevir, 14.9% and 0.01% of patients for sofosbuvir/velpatasvir, 14.6% and 2.3% of patients for sofosbuvir/velpatasvir/voxilaprevir, and 13.3% and 1.8% of patients for glecaprevir/pibrentasvir.
Data from a large population-based prescription data base showed that co-administrations of other drugs during DAA treatment are very frequent. Modeling pDDIs using the approved DAAs in Norway and the most commonly used co-medications showed a potential for grade 3 DDIs in 0.01-5.5% of patients, with the highest frequency of pDDIs in parietaprevir/ritonavir/ombitasvir. This emphasizes the importance of assessing patient’s co-medication prior to the initiation of DAA treatment.