A tablet for the controlled release of a drug. The tablet is in the form of an asymmetrically coated tablet so that immediate release or time-delayed release times can be precisely controlled and the extended release slab may provide zero-order or first-order extended release and pulsatile release depending on the excipients used in the tablet formulations. The core of the tablet is coated with an asymmetrical coating, that is, a coating with regions having different properties. The coatings may include drugs in varying concentrations. Further, different regions of the coating may have different rates of dissolution. The core of the tablet may be provided with a constant cross-sectional area along a longitudinal length of the tablet, a coating having a first region with a more rapid rate of dissolution than a second region. The dissolution of the first region exposes only the cross-sectional area to the dissolution medium. The second region of the coating prevents any other portion of the core of the tablet from being exposed to the dissolution medium. Therefore, since the cross-sectional area remains constant as it is dissolved, the rate of release of the drug from the core of the tablet remains constant. The cross-sectional area may be of any geometrical configuration so long as the area remains constant as the core dissolves.
