I take adderall (dextroamphetamine and racemic amphetamine) xr 25mg 2x day. then 5mg amphetamine 5mg salts at 5:00p.m. gor crashing. what's the difference between salts? mine don't have "m"

That's a fairly high: dose, so please monitor your blood pressure & pulse rate monthly. Mixed Amphetamine Salts are the generic form of Adderall (dextroamphetamine and racemic amphetamine). Only the shorter-acting preparation is sold as a generic medication. The molecular make-up is the same, although some generic preparations are a little weaker or stronger than brand-name. The XR delivery system works for ~ 12 hours, "regular" Adderall (dextroamphetamine and racemic amphetamine) or MAS for ~ 6 hours.