1. A sustained release matrix type preparation in which the carbonitrile derivative of N-acylpyrrolidine having an amino group in its molecule is stabilized, said preparation containing a normal base salt, which is hardly soluble in water, and also an excipient. 2. Sustained-release matrix-type preparation according to claim 1, characterized in that the carbonitrile derivative of N-acylpyrrolidine having an amino group in its molecule is vildagliptin, saxagliptin, melogliptin, denagliptin, TS-021, MP-513 or a carboxamide derivative of aminoacetinp represented by the general formula (1) (In the general formula (I): A represents CH, CHF or CF； R represents a hydrogen atom, a C1-C6 alkyl group which may be substituted, a C3-C8 cycloalkyl group which may be substituted , an arylmethyl group which may be substituted, an aryl ethyl group which may be substituted, an aromatic hydrocarbon group which may be substituted, an aromatic heterocycle which may be substituted or an aliphatic heterocycle which may be substituted； and n is 1 or 2). 3. Sustained-release matrix type preparation according to claim 1, characterized in that said carbonitrile derivative of N-acylpyrrolidine having an amino group in its molecule is vildagliptin, saxagliptin, melogliptin, denagliptin, TS-021, MP-513 or (28 48) -1- [N- (4-ethoxycarbonylbicyclo [2.2.2] oct-1-yl) amino] acetyl-4-fluoro-pyrrolidine-2-carbonitrile. 4. Sustained-release matrix-type preparation according to any one of claims 1 to 3, characterized in that said basic difficulty1. Препарат матричного типа с пролонгированным высвобождением, в котором карбонитрильное производное N-ацилпирролидина, имеющее в своей молекуле амино-группу, стабилизировано, причем указанный препарат содержит нормальную базисную соль трудно растворимую в воде, а также наполнитель.2. Препарат матричного типа с пролонгированным высвобождением по п.1, отличающийся тем, что карбонитрильное производное N-ацилпирролидина, имеющее в своей молекуле амино-группу предс
