Hepatitis C:Drug–drug interaction (DDI) may not be reflected in prescribing information

Medication use and medical comorbidity in patients with chronic hepatitis C 

The latest issue of the European Journal of Gastroenterology & Hepatology evaluates the high utilization of drugs with interaction potential in patients with chronic hepatitis C from a US commercial claims database

With the advent of the direct-acting antiviral agents, significant drug–drug interaction (DDI) potential now exists for patients treated for chronic hepatitis C virus (HCV) infection.

However, little is known about how often patients with HCV infection use medications that may interact with newer HCV treatments, especially those with cytochrome P450 3A (CYP3A) DDI potential.

Using a large US commercial insurance database, Dr Julie Lauffenburger and colleagues examined medication use and comorbidity burden among adult patients with a chronic HCV diagnosis from 2006 to 2010.

Medications were examined in terms of total number of prescription claims, proportion of patients exposed, and DDI potential with the prototypical CYP3A direct-acting antiviral agents boceprevir and telaprevir, for which data were available.

Patient comorbidity burden was high and increased over the study period.

Medication use was investigated in 53,461 patients with chronic HCV.

The researchers found that 53% of the top 40 most utilized medications were classified as having interaction potential, with 62% of patients receiving at least one of the top 22 interacting medications by exposure.

Of these, 59% and 41% were listed in a common DDI resource but not in medication-prescribing information.

The team noted that 77% had not been investigated in DDI studies.
The research team found that 41% and 36% did not have clear recommendations for DDI management, and only 14% and 23% carried a recommendation to avoid coadministration for boceprevir and telaprevir, respectively.

Dr Lauffenburger's team commented, "Practitioners may expect a medication with CYP3A DDI potential in two-thirds of patients with HCV and may expect almost one-half of the most frequently used medications to have CYP3A DDI potential."

"However, DDI potential may not be reflected in prescribing information."

European Journal of Gastroenterology & Hepatology:

October 2014 - Volume 26 - Issue 10 - p 1073-1082

doi: 10.1097/MEG.0000000000000152

Original Articles: Hepatitis