Any additives that you find in encapsulated herbals is inevitably going to be a "flow agent", or "packing agent". The flow agents allow the herb to travel through a hopper and into the capsules during the manufacturing process. It also helps the machine in that the parts do not get clogged up as much. The packing agents are for powders that are too slick - where they just fall all over and cannot be controlled. By adding rice or maltodextrin, the powder gets stickier and will pack into the capsules much more readily.
All manufacturers/encapsulators must follow strict FDA guidelines. Any additive must be at a very low percentage - so much so that a person's body will not exhibit side effects. These ingredients are listed as "inactive" so that persons with known allergies can avoid them.
I know, because I worked for NBTY (Nature's Bounty and Vitamin World) for many years.