King Pharmaceuticals, Inc. has agreed to acquire Alpharma, Inc. for approximately $1.6 billion. The agreement, if approved by shareholders, will expand King’s pain drug business with Alpharma’s drug Kadian and pain patch Flector. Alpharma also has an experimental pain drug Embeda.     An FDA advisory panel recently stated that the morphine-based Embeda is somewhat less attractive to drug abusers, which the agency may require the company to claim on its label. King and partner Pain...