https://en.wikipedia.org/wiki/Phenylpropanolamine
The compound exists as four stereoisomers, which include d- and l-norephedrine and d- and l-norpseudoephedrine.[8][4] d-Norpseudoephedrine is also known as cathine,[3][8] and is found naturally in Catha edulis (khat).[9] Pharmaceutical drug preparations of PPA have varied in their stereoisomer composition in different countries, which may explain differences in misuse and side effect profiles.[4] Analogues of PPA include ephedrine, pseudoephedrine, amphetamine, methamphetamine, and cathinone.[7]
There are four optical isomers of PPA: dextro- and levo-norephedrine, and dextro- and levo-norpseudoephedrine. d-Norpseudoephedrine is also known as cathine, and occurs naturally in Catha edulis ("Khat").[10]