Apparently, your body uses something called glucuronic acid and binds it to retinoic acid molecule. And then it's able to excrete it out of your bile.
But, there's an enzyme called beta-glucosidase that will un-bind the two and thus reactivate Accutane causing a viscous cycle. BUT there's a supplement called Calcium D-Glucarate that inhibits this process, thus allowing your body to eliminate more Accutane.