Currently, pharmaceutical amphetamine is prescribed as racemic amphetamine, Adderall, dextroamphetamine, or the inactive prodrug lisdexamfetamine. Racemic amphetamine contains two optical isomers, dextroamphetamine and levoamphetamine. Presently, it is typically prescribed as mixed amphetamine salts, dextroamphetamine, and lisdexamfetamine. These include methylphenidate (e.g., Ritalin) and dextroamphetamine, among others. The amphetamine molecule exists as two enantiomers, levoamphetamine and dextroamphetamine. Propylhexedrine is used recreationally in a similar manner to amphetamine, methamphetamine and dextroamphetamine. The conversion rate between dextroamphetamine sulfate to amphetamine free base is .728. Amphetamine is a chiral compound which is composed of two isomers&colon; levoamphetamine and dextroamphetamine. Lisdexamfetamine dimesylate is one marketed formulation delivering dextroamphetamine. Amphetamine was discovered in 1887 and exists as two enantiomers&colon; levoamphetamine and dextroamphetamine. The conversion rate between lisdexamfetamine dimesylate (Vyvanse) to dextroamphetamine base is 29.5%. Chemically, lisdexamfetamine is composed of the amino acid -lysine, attached to dextroamphetamine. Levoamphetamine also provides Adderall with a longer clinical effect than dextroamphetamine. Another pharmaceutical that contains dextroamphetamine is commonly known by the brand name Adderall. Dextroamphetamine sulfate is the most common enantiopure salt.