There is. I thought I had some on the shelf, but I must have used it up. Can't remember the name, but paint stores or big box stores should carry it. It will remove dried paint from brushes, even loosen dried paint in sprayers. Has a very bad/strong odor, so use in a well ventilated area. You just have to decide if buying the cleaner and spending the time cleaning the brush is worth it or if it's better to just pitch it like chrisn suggested.
If you buy a $20 paintbrush you will clean it spotless after each use and never need the cleaner product. If you buy a $2 paintbrush it wont be worth buying the stuff and the time to use it, and then there are people like me that buy the $2 paint brush and clean it and use it for 10 years.
let the brush soak in a saturated solution of water and TSP [tri-sodium-phosphate ] over night, or maybe longer , depending on how crapped up the brush is, it will soften the paint so it can be cleaned off the brush