Reactivation of chronic hepatitis B during treatment with tenofovir disoproxil fumarate: drug interactions or low adherence?

We describe a case of a 61-year-old man with chronic hepatitis B, hepatitis B e antibody (HBeAb) positive, treated with tenofovir disoproxil fumarate (TDF), who developed virological and biochemical viremic reactivation with an increase in transaminase plasma levels. The patient's history revealed that he had discontinued TDF about 5 days before admission and, from December 2013, had been taking venlafaxine, paroxetine and zolpidem for some episodes of depression. Clinical evaluation and laboratory findings excluded the presence of systemic diseases that might have been able to explain the drug inefficacy, while pharmacological evaluation suggested a possible drug-drug interaction. In order to assess the possible occurrence of resistance, mutational analysis of hepatitis B virus (HBV) was performed and excluded the presence of resistance for TDF. TDF was prescribed, and venlafaxine, paroxetine and zolpidem were discontinued. The follow-up at 3, 6 and 12 months documented a good response to TDF with a time-related decrease of HBV-DNA and alanine aminotransferase.