Adderall and Adderall XR - Any Difference?

There is a difference between "common" Adderall and Adderall XR. XR means "extended release", i. e., the dose of the medication is released into the systme during a longer period of time as compared to the instant-release form. The effect is achieved due to the special formulation of Adderall XR which consists of four different amphetamine salts metabolized at different rates. They are:

dextroamphetamine saccharate dextroamphetamine sulfate (racemic dextro/levo-amphetamine) aspartate monohydrate (racemic dextro/levo-amphetamine) sulfate

That is why the extended-release form of the medication has a milder action as compared to single-salt amphetamine preparations. Adderall XR is a later product by Shire Pharmaceuticals. It was put on the market in 2001, five years after instant-release form of Adderall brand.