Risperdal is a common drug form anxiety, it is an anti-psychotic at much higher levels. I take Seroquel for my anxiety, it takes it down to a dull roar. I used Luvox for years and really liked it, you just have to watch your sweet tooth:)
Risperdal is an anti-psychotic but that's a subclinical dose so perhaps your psychiatrist prescribed it for panic attacks but I haven't heard of it for that use though it may have some effects. There is no particular interaction between the two medications. If it helps then see what happens. At that small dose there shouldn't be many problems and at any dose those two medications can be used together safely.