Study on Solventing-out Crystallization Process of Levoamlodipine

OBJECTIVE To study the solventing-out crystallization process of levoamlodipine. METHODS The gravimetric method was used to measure the solubility of levoamlodipine in the mixture of n-heptane and dichloromethane. It is studied the effect factors on the purity and the yield of levoamlodipine crystallization which included the temperature, the quantity of anti-solvent, the flow rate of n-heptane introduced into levoamlodipine dichloromethane solution and the rotary speed. RESULTS The solubility of levoamlodipine in the mixture increased remarkably during the reduction of the n-heptane’s ratio at the fixed temperatures. The optimized condition was temperatures: 25 ℃; the mass ratio of n-heptane to dichloromethane: 1.5-1.75; rate of rotation: 300 r·min^-1. CONCLUSION The product obtained from the crystallization process has the higher purity and yield. The technology has the advantages such as simple operation, easy-to-industrialization and so on. What is more, it is opening up good prospects for preparation of the single amlodipine enantiomer of a variety of formulation.