AstraZeneca's ($AZN) brand-new Movantik has an edge on rivals in the opioid-induced constipation (OIC) market, which is expected to near $2 billion by 2017. It's the first mu-opioid approved for OIC, and the first mu-opioid pill, period. But AZ has some market-making to do, and its pill won't be rival-free for long. Report