Improved Manufacturing Process for Pyronaridine Tetraphosphate

Pyronaridine tetraphosphate (1) is a well-known antimalarial drug. However, it required a carefully optimized production process for the manufacture of pyronaridine tetraphosphate. Each step of its manufacturing process was reinvestigated. For the cyclization of 4-chloro-2-(6-methoxy-pyridin-3-yl-amino)-benzoic acid 6 to 7,10-dichloro-2-methoxybenzo[b]-1,5-naphthyridine 5, an improved process was developed to eliminated critical process impurity (BIA). By the redesign of the formation of triphosphate salt, the purity as API grade was increased. Thus, a robust manufacturing process with an acceptable process performance has been developed to produce high quality pyronaridine tetraphosphate.