Antiviral agents: A journey through time to discover new uses and advancements

Background Viruses are microscopic infectious agents composed of nucleic acid enclosed within a protein coat and are not visible to the naked eye. Viral infections, including those caused by HIV, influenza, respiratory syncytial virus (RSV), and SARS-CoV-2, continue to pose significant global health challenges. Although antiviral medications—particularly entry and fusion inhibitors—have shown therapeutic potential, many currently available drugs exhibit limited spectrum of activity and suboptimal efficacy. The emergence of new viral strains and drug resistance highlights the urgent need for the development of novel, broad-spectrum, and non-toxic antiviral agents. Methods This review comprehensively examines the mechanism of action, pharmacokinetics, and therapeutic efficacy of antiviral drugs, with a particular focus on entry and fusion inhibitors. It also evaluates antiviral agents approved since 2018, along with those under ongoing clinical investigation. Special emphasis is placed on drugs targeting major viral pathogens such as HIV, SARS-CoV-2, RSV, and influenza. Representative antiviral agents, including Tecovirimat, Fostemsavir, and Molnupiravir, are analyzed in detail. Results Recent advancements in antiviral drug development have led to the approval of several novel agents with improved mechanisms of action and therapeutic profiles. Drugs such as Tecovirimat, Fostemsavir, and Molnupiravir demonstrate promising pharmacokinetic properties and enhanced antiviral efficacy. However, many antiviral therapies still suffer from limitations, including narrow activity spectrum, potential toxicity, and the emergence of resistant viral strains. Ongoing clinical trials are exploring innovative antiviral molecules and fusion protein inhibitors with improved safety and broader applicability. Conclusions Despite significant progress in antiviral therapy, there remains a critical need for the development of broad-spectrum, non-toxic, and resistance-resilient antiviral agents. Continued research focusing on innovative drug targets and advanced therapeutic strategies is essential to effectively combat emerging and re-emerging viral infections and to safeguard global public health.