Antiviral:An agent that kills avirusor that suppresses its ability to replicate and, hence, inhibits its capability to multiply and reproduce.
For example,amantadine(Symmetrel) is a syntheticantiviral. It acts by inhibiting the multiplication of the influenza A virus. It was used to lessen the severity of thedisease, particularlyinindividuals at high-risk such as those who are immunosuppressed or in a nursing home. Amantadine has been replaced by safer medicines, oseltamivir (Tamiflu) and zanamivir (Relenza) which have fewerside effects.
Thedevelopmentof antivirals has lagged far behind that of antibiotics. A virus is justgeneticmaterial,DNAorRNA, perhaps with a fewenzymes, wrapped in aproteincoat. Aviralis technically not alive which makes it hard to kill. Further,virusesreplicate (make copies of themselves) by hijacking the machinery of thecellthey infect, so it is difficulty to kill the virus without killing the cell. Some viruses can also remain dormant in the body without replicating, thereby avoiding drugs that inhibitreplication.
The antivirals that have been developed are generally less effective than one would like. Viruses can replicate rapidly and, in many cases sloppily, giving rise to mutations that make them resistant to drugs. And for fast-moving viral infections like flu or a cold, a drug must be very powerful to make a difference before the disease runs its natural course.
