A completely uneducated reply: No, I think you'll be fine if you accidentally take a double dose, or for that matter skip a dose. Toprol XL is the timed released version of Metoprolol. I use to take Toprol XL, until I discovered the far cheaper Metoprolo. The primary difference is that I must take it twice a day instead of only once. I've taken a double dose on many occasions to aid conversion of SVT episodes. You could feel a little woozy if you stand up quickly or perhaps bend over, but I doubt you'll notice much of a difference.