Don't know yet exactly how it works. A. Amantadine - first antiviral developed. May prevent virus from entering cell or from uncoating. A prevention, but not much good once the disease is established B. Ribavarin - analogue of guanine. Only works against herpes viruses.
Several derivatives have a similar mode of action.
D. Ganciclovir - like acyclovir, an analogue of guanosine. Both are used topically to treat herpes keratitis. Useful in chemotherapy of HIV infections. G. Relenza and Tamiflu, inhibitors of neuraminidase may be used in the treatment of influenza, but they only shorten the period of illness by a day or two. Antiprotozoan and antihelminthic drugs A. Quinine and synthetic derivatives like chloroquine, mefloquine and quinacrine are antiprotozoan agents.