It is difficult to attain good selective toxicity with antiviral drugs because of the fact that view available hint(s) it is difficult to attain good selective toxicity with antiviral drugs because of the fact that viruses are not living organisms viruses require host cells to replicate themselves viruses are not cells viruses can hide in an envelope from the host cell

Viral drugs are prescription medicines used for treating viral infections (viruses) rather than bacterial ones. These medications can be only bought with a prescription from your doctor 
It is difficult to attain good selective toxicity with antiviral drugs because of the fact that viruses require host cells to replicate themselves.

I believe it is difficult to attain good selective toxicity with antiviral drugs because of the fact that viruses require host cells to replicate themselves.  The Antiviral Drugs have limited selective toxicity because viruses mostly use host cell machinery and therefore there are very unique targets. Most of these drugs block steps that take place within cells, increasing chances for cell toxicity. 

The light is great source of energy

Active site is where they touch.