A method for producing a sustained-release tablet having improved stability and content uniformity is provided. The method involves first preparing a core tablet by granulating, drying, milling, blending, and compressing a mixture of active and inactive ingredients. Four coating layers are applied to the core tablet: an inner layer, an enteric coating layer, an active layer, and an outer layer. The active ingredient may be a tetracycline, such as doxycycline. A sustained-release tablet prepared according to the method is also described.
