Are naphcon-a eye drops safe for contact lens use at the same time?

Not recommended. If you are having allergic symptoms, like itching, watering and redness. Take out your contacts, and then put in allergy drops. Btw, zaditor (ketotifen) is much better than naphcon-a.
Usually. As long as you are certain that what you are treating is allergic, than you can use naphcon-a even while wearing the lenses. However it is a good rule of thumb to prevent any problems, to remove your contact lenses whenever an eye gets any degree of redness.