Drug-drug interactions are more likely to occur in elderly patients receiving direct antiviral agents (DAAs) for chronic hepatitis C virus (HCV) infection, however these interactions and their associated adverse events can be avoided with careful assessment of concomitant medications. Those are the findings of a new study published in Alimentary Pharmacology and Therapeutics.

A total of 541 patients, who presented to an outpatient clinic for treatment of chronic HCV infection after they were approved for sofosbuvir, were included in the study. The patients received different combinations of DAA therapy, including:  ledipasvir/sofosbuvir ±ribavirin; daclatasvir/sofosbuvir ±ribavirin; paritaprevir/ombitasvir ±dasabuvir ±ribavirin or simeprevir/sofosbuvir ±ribavirin in Genotype 1/4, and daclatasvir/sofosbuvir ±ribavirin or sofosbuvir/ribavirin in Genotype 2/3. 

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For the analysis, the authors divided the patients into 2 groups: ages ≥65 years (n=137) and ages <65 years (n=404).

Ninety-eight percent (n=134/137) of the ages ≥65 years group achieved sustained virological response rates (SVR). There was no virological treatment failure for those patients who received at least 80% of the intended treatment duration. In the ages <65 years group, 91% (n=369/404) achieved SVR. The SVR rate in this group, for those who received at least 80% of the intended treatment duration was 95%.

The proportion of concomitant medications was significantly higher for the ≥65 years group than the <65 years group (79% vs. 51%; P<0.0001). Cirrhosis patients aged ≥65 years had the highest number of concomitant drugs with a median of 3 per patient. The proportion of predicted clinically significant DDIs wassignificantly higher in elderly patients (54% vs. 28%; P<0.0001), according to the hep-drug interactions database.  

In their study, the authors took actions to reduce the potential impact of previously reported significant DDIs. The number of patients experiencing treatment-associated adverse event rates were similar in both groups, 63% and 65% for the ≥65 years group and the <65 years group, respectively. However, no significant adverse events were attributed to DDIs. The authors suggest that this may be attributable to the meticulous DDI assessment before treatment initiation and monitoring during treatment.

The authors concluded that while concomitant drugs can present a risk of serious DDIs, “Use of a free accessible Internet-database and careful management during therapy can effectively prevent DDI-associated adverse events and treatment failure.”

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