Potentially 300mg of codeine could produce anything up to 200mg of morphine/morphine-6-glucuronate
I hate to break everybody's hearts, but typically 10% of codeine is bioconverted to morphine, and 5-15% are excreted unchanged as codeine, while the rest is metabolized into the BIOLOGICALLY INACTIVE codeine-6-glucuronide and morphine-6-glucuronide.
The grapefruit juice will help
reduce the 5-10% of codeine converted to the half-as-active (compared to codeine) norcodine and the 5-10% of the 10% of morphine which are converted to the half-as-active (compared to morphine) normorphine. This will improve the potency overall by between 0% and 2.5%, depending upon how much it inhibits the N-demethylation enzymes.
The idea of recycling the drugs in one's urine IS a sound one, but you can't magically expect the total amount of active material in your urine (and thus the high from it) to ever exceed the amount in your body at the time of urination. In other words: you are ALWAYS going to get LESS high from drinking your pee than you were at the time you created that pee.
Also, the only way to metabolise a majority of injested codeine into MORPHINE (not any of the other weaker/inactive metabolites), is to somehow significantly induce your CYP2D6 enzymes to work faster, while inhibiting your CYP3A4 enzymes.
Unless of course you're this lucky fuck:
http://content.nejm.org/cgi/content/short/351/27/2827 [smile]
By the way, I've heard cimetidine and quinidine PREVENT codeine from being metabolised into morphine.
If you read enough patents at
http://gb.espacenet.com you'll learn that the epoxy bridge and overall structure of the opiates is much more stable than commonly believed, and that the 3-O-methyl position is typically the first to break in certain conditions. (boiling mineral acids) All opiates with a ketone at the 6 position are even more stable (including hydrocodone and oxycodone), and demethylation is pretty selective to the 3-O position.