Valium, for example, goes into your system very fast. It goes out slowly. It has moderate addiction potential. Librium goes in you system slowly and goes out slowly, too. It is not at all addictive.
Cocaine goes in and out very fast.
It is very addictive. There are two drugs which are commonly used in children with anxiety in this group. Along the way people started using it in anxiety disorders. It lasts a long time in your body after a dose, so it only needs to be given once or twice a day. It is very unlikely to produce withdrawal, and since it goes into your system slowly, it does not make people high nor is it very addictive.