Interesting, That's the type of system I was referring to in my initial
post.  Assuming your friend means that ALL pharmacies are connected
with each other, not just pharmacies who share the same name.  For
instance, here in the states, all Walgreens are connected but for
states without their own individual prescription monitoring service,
that does nothing to stem diversion because their are hundreds of
different stores that don't share information.

You talk about the Oxy problem.  It was in large part a creation of the
media.  The evening news tells everyone that Oxy is "Hillbilly Heroin".
Before it made the news few people outside the medical community and
pain patients had ever heard of this drug.  And then the next day a
pharmacy is robbed at gunpoint and they ask for OxyContin by name.
Golly, I wonder where the junkies ever got this idea?  It's almost as
if they'd seen it on TV.  After making OxyContin a household name and
effectively telling the junkies what to ask for when they rob
pharmacies, then the media reports on the pharmacy robberies that they
played a clear role in.  They actually helped to make the news they are
reporting.

And one of the reasons junkies turned to Oxy was because the DEA was
squeezing their heroin supply.  Can't get heroin, so switch to
prescription drugs.

Capitalism is the most powerful force known to man.  As long as
somebody is willing to pay for drugs, there will be a supply.  The only
thing the DEA and other law enforcement can do is cut down on supply.
That raises prices and creates additional crime.  If a junkie steals
your car or robs you at gunpoint to pay for their expensive drug habit
(a habit that is only expensive due to prohibition) will you send the
DEA a thank you note telling them how safe they make you feel?

Milton Friedman estimated that drug prohibition results in 10,000
additional homicides each year in the US.  Do you wish to disagree with
a Nobel Laureate?  Every war results in death and the War On Drugs is
no different.