Worries over slowing global sales of Abbvie Inc.'s largest product, Humira (adalimumab), and fears about the outlook for Amgen Inc.'s Enbrel (etanercept) dimmed the shine on shares of both companies by Friday's close, shaving 6.3 percent from Abbvie shares (NYSE:ABBV) and pushing Amgen shares (NASDAQ:AMGN) shares down 9.6 percent.