Quote Originally Posted by Nullific
Pseudoephedrine has far less activity in the central nervous system than ephedrine, being the dextrorotatoryisomer. You may feel some adrenergic stimulation, far from my recreational stimulant of choice though.
Pseudoephedrine is not the optical isomer of ephedrine, if that's what you meant. There is a D and an L-isomer to both, L being the form which is in over the counter medications. Pseudo differs from ephedrine in the position of the beta-hydroxy group, relative to the alpha-methyl carbon. Since meth is made by removing this group, it make no difference which you start with. Pseudoephedrine has little or no recreational value.