... to know if Adderall XR (extended-release) has a different half-life or simply a longer period before the breakdown process begins. Is it processed by the liver or kidneys? Is it water soluble or fat soluble? Finally, is it known to have any serious reactions with types of drugs.. namely opioid intake inhibitors ( methadone, suboxone, subutex) and anti-depressants ( seroquel, lithium, paxil, lexapro.etc... )