Take it for more than 3 or 4 days and you start crapping little chunks of off-road tires.
Mu opioid receptors in both the brain and colon. One gives you pain relief, the other virtually stops colon activity. This can be treated with Relistor (a narcotic antagonist that does not cross the blood-brain barrier--but it is expensive and the dose should really be higher)
As many problems as I see dispensing hydrocodone products, changing the prescribing process will not help. Prescription monitoring programs that report all controlled substances to a central data base allow prescribers and pharmacies to identify problems like doctor shopping.