In clinical studies, carbamazepine suspension, conventional tablets, and extended-release tablets delivered equivalent amounts of drug to the systemic circulation. However, it has been observed that the suspension is somewhat faster absorbed. Furthermore, the extended-release tablet is slightly slower than the conventional tablet. The bioavailability of the extended-release tablet is 89%, compared to the suspension. Plasma levels of carbamazepine are variable. The time to peak concentration for the different formulations are as follows: Suspension = hours; Conventional tablets = 4-5 hours; Extended-release tablets = 3-12 hours.