Of all the companies to make it onto this year's Fastest-Growing list, Impax Labs has likely produced the most volatile results. Over the past five years, net income has fluctuated significantly from as low as $16 million in 2006 and 2008 to as high as $250 million in 2010, and several points in between. The self-described "technology-based speciality pharmaceutical company" specializes in "controlled-release" generic versions of brand-name drugs. Among its biggest sellers are migraine-treating drug Zomig, and Adderall XR, which is used to treat attention deficit disorder. In 2010, net income sky-rocketed 400%. Impax put this down to a one-time accounting benefit, along with increased sales of several key products. Last year profits came crashing down 74%, however, as global sales declined across the board and supply disruptions affected Adderall XR. -- N.S.