UPDATE 2-Galenica to buy biotech firm Relypsa for $1.5 bln, ahead of split
* Deal brings worldwide rights to potassium medicine * Builds up Vifor Pharma unit ahead of 2017 split * Galenica shares down 7 percent (Adds analyst reaction, latest shares, advisers) By Sylwia Lasek and Ben Hirschler July 21 (Reuters) - Galenica has agreed to buy Relyp
