AMLODIPIN BENZOLSULFONATE PREPARATION METHOD Russian patent published in 2004 - IPC

FIELD: pharmaceutical chemistry. SUBSTANCE: invention relates to improved method for preparing amlodipin benzolsulfonate, which is also known as amlodipin bezilate and is really 2-[(2-aminoethoxy)methyl]-4-(2-chlorophenyl)-1,4-dihydro-6-methyl- 3,5-pyridinedicarboxylic acid 3-ethyl-5-methyl ester benzolsulfonate salt, which is worthy antiischemic and antihypertensive compound. Preparation consists in adding aqueous benzenesulfonic acid solution to above named ester preliminarily suspended in water, keeping resulting mixture for 8-10 h at 30-50 C, preferably at 35 C, separating thus obtained amlodipin benzolsulfonate, drying and purifying product by dissolving it in methanol, heating resulting suspension to 45-50 C, adding charcoal followed by stirring, vacuum filtration, and removing methanol, after which is added ethyl acetate, reaction mixture is heated to 55-60 C, kept at this temperature for 1.5, cooled to 18-20 C, and aged for 1 h before vacuum filtration giving product, which is washed with ethyl acetate and dried. Purity of product is 99.5-99.8%. EFFECT: minimized level of polar solvents in product so that it cannot be used for preparing drugs without further purification. 1 tbl