Antiviral drug referred to those drugs or chemical agents that are used for the treatment of viral infection. There are present several types of antiviral drugs that are used for the treatment of viral infections such as Amantadine, Acyclovir, Azidothymidine, Ganciclovir, Abacavir. Each of these antiviral drugs follows a different mechanism. The variation in their mechanism depends on the types of virus.