Success isn't guaranteed, but both companies could become big winners.Viking Therapeutics (VKTX -0.84%) and Madrigal Pharmaceuticals (MDGL -1.41%) are highly prominent biotech companies that have a lot in common. Both focus on treating metabolic illnesses like liver disease and obesity, and, until recently, despite their promising pipeline programs, both were lacking any products on the market to generate revenue.Now, the picture is shifting, and the odds are good that one of these players will pull ahead o ...