Shares of Progenics Pharmaceuticals Inc. (NASDAQ:PGNX) spiked Friday after the company reported that prescriptions of opioid-induced constipation (OIC) drug Relistor (methylnaltrexone bromide) increased by 90 percent in the fourth quarter of 2012 compared to the same period in 2011, growing by 137 percent for the full year compared to 2011.