Q1. Not sure. Enrico imagines that if you stopped using codeine
for about 2 months you'd be pretty close to baseline tolerance but it'd probably take a couple months more to get it right down (Enrico doesn't think he could handle going without for that long)
Q2. Enrico believes that the upper limit does still apply to those with tolerance. Tolerance is an opiod-receptor related phenomenon. It's got nothing to do with liver enzymes.
Q3. Hmmm... Enrico has no idea.
Q4. That certainly is weird. Enrico finds he pisses significantly less after having codeine. Just as an aside, nothing makes him piss more than LSD
, leaving him with the worst hangover imaginable. He has never heard of this happening to anybody else though. Different people, different effects.