How does wing tip missile affect induced drag?

Induced drag is the American (actually german) term for the pressure drag due to downwash on the wing tips. How do the missiles placed on the tips of the wing affect this drag?, if it does at all. Is there a way of putting a winglet and a wingtip missile on the same wing. (winglets stop the high pressure from going on the top of the wing that creates downwash and later vortex)