 Unlike most antibiotics, antiviral drugs do not destroy their target pathogen; instead they inhibit their development.Antiviral drugs are one class of antimicrobials, a larger group which also includes antibiotic (also termed antibacterial), antifungal and antiparasitic drugs, or antiviral drugs based on monoclonal antibodies.Most antivirals are considered relatively harmless to the host, and therefore can be used to treat infections.