Developments in small molecule antiviral drugs against hepatitis B and C viruses: FDA approved therapies and new drugs in clinical trials

Given the continuous emergence of hepatitis and the associated consequences, developing effective antiviral strategies has become a major public health concern. Current antiviral strategies for the treatment of hepatitis, especially for hepatitis B virus (HBV) and hepatitis C virus (HCV), and those under discovery and development are broadly classified into two categories, i.e., biologics and small molecules. These therapeutic classes include small molecule modulators, peptides, nucleic acid polymers, small interfering RNA (siRNA), antisense oligonucleotides, monoclonal antibodies, and vaccines. To date, several small molecule antiviral agents targeting HBV and HCV have advanced into different phases of clinical investigation for monotherapy and/or combination therapy. In ongoing clinical investigations, researchers are testing small molecule-based antiviral therapies that mainly target complex molecular interactions between virus and host cells involved in viral replication. An up-to-date comprehensive analysis is required to examine the current state of antiviral drug discovery and understand the new trends in antiviral approaches. In the present compilation, we have highlighted the FDA-approved therapies for HBV and HCV with a special focus on the ongoing clinical developments of small molecules for the treatment of hepatitis.