Abstract: The present disclosure describes a novel, cost-effective process for preparation of a 4-oxo-1,2,3,6,7,11b-hexahydro-4H-pyrazino-[2,1-a]isoquinoline derivatives. Specifically, it discloses a process for the preparation of the anthelmintic drug praziquantel through the use of a novel intermediate, 2-[(2,2-dimethoxyethyl)benzyl amino]-N-phenethylacetamide. This present disclosure also describes a novel crystalline form of 4-oxo-1,2,3,6,7,11b-hexahydro-4H-pyrazino[2,1-a]isoquinoline.

Abstract: The present invention relates to a process for the preparation of succinylcholine chloride, a pharmaceutically active compound used as skeletal muscle relaxant which comprises condensing succinic anhydride with N,N-diemthylaminoethanol using a catalyst in presence of a solvent to form bis[2-(dimethylamino)ethyl]succinate; in situ purifying the bis[2-(dimethylamino)ethyl]succinate using a base; reacting pure bis[2-(dimethylamino)ethyl]succinate with methyl chloride gas using an alcohol; and purifying the obtained crude succinylcholine chloride using water and alcohol.

Abstract: The present invention discloses a stable amorphous form of Rifaximin characterised by having X-ray powder diffraction pattern as given in FIG. 1, having a 2? peaks at 7.2 and having moisture content in the range of 3% to 4% preferably, 3.4% to 3.7%. This invention also discloses a novel process for its preparation.

Abstract: The present disclosure describes a novel, cost-effective process for preparation of a 4-oxo-1,2,3,6,7,11b-hexahydro-4H-pyrazino-[2,1-a]isoquinoline derivatives. Specifically, it discloses a process for the preparation of the anthelmintic drug praziquantel through the use of a novel intermediate, 2-[(2,2-dimethoxyethyl)benzyl amino]-N-phenethylacetamide. This present disclosure also describes a novel crystalline form of 4-oxo-1,2,3,6,7,11b-hexahydro-4H-pyrazino[2,1-a]isoquinoline.