Preparation method of dexmethylphenidate hydrochloride sustained-release capsule

The invention provides a dexmethylphenidate hydrochloride sustained-release capsule, the capsule takes a dexmethylphenidate hydrochloride sustained-release micro-tablet as a drug carrying unit, the micro-tablet comprises a quick-release layer and a sustained-release layer, and the quick-release layer comprises dexmethylphenidate hydrochloride, a filler I, a disintegrating agent and pharmaceutically acceptable auxiliary materials; the sustained-release layer comprises dexmethylphenidate hydrochloride, a filler II, a sustained-release material and pharmaceutically acceptable auxiliary materials, the average diameter of the micro-tablet is 3-10mm, the height of the quick-release layer is 1-4mm, the height of the sustained-release layer is 2-6mm, the particle size distribution of dexmethylphenidate hydrochloride is that D50 is more than or equal to 50 microns and less than or equal to 100 microns, D90 is more than or equal to 110 microns and less than or equal to 180 microns, and the particle ...