After months of anticipation, the FDA has issued a so-called final guidance for approving new treatments that contain more than one drug, so-called fixed-dose combinations, and the agency decision is likely to stir controversy because untold amounts of money may be at stake. Here’s why. Until now, five years of valuable marketing exclusivity are available if all of the drugs in the combination are new chemical entities, in other words drugs that were not previously approved for any use. A fixed-dose combination containing an older drug would be eligible for three years of exclusivity instead. Those two years can make a difference, of course, for drug makers that have a big-selling product and have additional time to ring the register before another version arrives in pharmacies or hospitals. And so, a few drug makers petitioned the FDA last year to change its rules so that a fixed-dose combination with at least one new chemical entity was eligible for five years of marketing exclusivity.