they only reason is being change is to stop kids from making
meth...phenylephrine raises blood pressure more than the pseudo..

here is the little twist...

 If you take a look at the phenylephrine molecule, you will see that
it is a benzene ring with two substituents, a hydroxy group and a
methyl amino alcohol group meta to one another.

       What applies here are the rules of electrophilic aramotic
substitution. Now, the hydroxy group (the OH on the benzene) is ortho
para directing and activating and it is the most important; what you
have here is a substituted phenol, and phenols are highly activated.
The methylaminoalcohol group is also ortho para directing and
activating, but is not controlling because its benzylic alcohol is
very reactive itself.  If one reacts this molecule with the typical
HI/RP reaction conditions, Iodation will occur at two places on the
benzene ring and on the alcohol group of the methylamino as follows:

       On the benzene, iodation will occur ortho and para to the
phenol,
but not between the hydroxy and the amino alcohol because of steric
hinderence, so taking a benzene ring with the methyl amino alcohol as
carbon position number 1 and counting to the right around the ring,
carbon 2 is empty, carbon 3 has the OH, carbon 4 has an I, carbon 5
is empty, carbon 6 has an I, and the methylamino has an I in place of
its OH.  So, for phenylephrine, three times as much iodine is needed
for the reaction as normal.

       Now, when the reaction goes to completion one has a di-iodo
hydroxy
methamphetamine.  THIS IS NOT A PROBLEM AT ALL.  Hydroxy amphetamine
and hydroxy methamphetamine  are both very powerful stimulents and
quite pleasurable.  In fact they are so good that I would defy you to
tell it from the non hydroxy form.