Obtaining the Enoxaparin Sodium Substance Equivalent to the Original Clexane® and Lovenox®. The Selection of Technological Parameters and Optimization of the “Greenness” of the Purification Stage

Abstract

The aim of the study was to adjust and optimize the purification stage of crude enoxaparin sodium to obtain a substance equivalent to the original drugs Clexane® and Lovenox® according to the criteria specified by the FDA. The purification stage involves the reprecipitation of crude enoxaparin in methanol. Determining the ratio of solvents required for the reprecipitation is important for studying the correlation between the experimental conditions of the technological process and the structural characteristics of enoxaparin samples. In the study, the method of purification of enoxaparin sodium described in the patent was assessed, and the following variations of the MeOH:H2O solvent ratio were selected – 4:1; 2:1; 1:1. The obtained samples of enoxaparin sodium were analyzed according to the in-house specification developed on the basis of the pharmacopoeial monograph, as well as by non-pharmacopoeial methods, such as two-dimensional NMR spectroscopy (HSQC) and size exclusion chromatography (SEC) for detailed characterization of the molecule. Strategies of greening of the enoxaparin sodium purification stage by reducing the E-factor were also considered in the study. Considering the principles of “green” chemistry, the method of purification of crude enoxaparin sodium was optimized by the solvent regeneration. It was experimentally possible to demonstrate the effect of the solvent ratio at the stage of purification of crude enoxaparin on the composition, as well as on the number and distribution of oligosaccharide fractions in the molecule. Based on the results of the study, it can be concluded that the ratio of MeOH:H2O=1:1 allows obtaining samples that are closest to Clexane® and Lovenox® in terms of the molecular weight distribution profile and the composition profile. The E-factor was also reduced from 14 to 5.25 by solvent regeneration.