High-pressure liquid chromatographic feprazone determination in pharmaceutical formulations.

A high-pressure liquid chromatographic method was developed for the quantitative determination of feprazone, a nonsteroidal anti-inflammatory agent, in different pharmaceutical formulations. The results agree with those obtained with GLC and UV spectrophotometric assays.

Chemical characterization of decomposition products of pyrazolidinedione-3,5 derivatives. Part 1: Identification of decomposition products and mechanism of degradation of 4-prenyl-1,2-diphenyl-3,5-pyrazolidine-dione in an aqueous solution.

From an aqueous solution of 4-prenyl-1,2-diphenyl-3,5-pyrazolidinedione sodium salt (Prenazone) subjected to accelerated ageing at 80 degrees C in anaerobic and in aerobic conditions the following decomposition products were isolated: N,N'-diphenylhydrazide-5-methyl-4-hexenoic acid,N,N'-diphenylhydrazide-2-carboxy-5-methyl-4-hexenoic acid, N,N'-diphenylhydrazide-2-carboxy-2-hydroxy-5-methyl-4-hexenoic acid, trans- and cis-azobenzene. The isolated compounds were identified by means of thin-layer chromatography, elemental analyses, UV, IR spectrophotometry and taking into consideration their chemical transformations. A decomposition mechanism of Prenazone Sodium in aqueous solutions maintained at 80 degrees C is proposed.

Chemical characterization of decomposition products of pyrazolidinedione-3,5 derivatives. Part 2: Chemical transformations of 4-prenyl-1,2-diphenyl-3,5-pyrazolidinedione (prenazone) and its main decomposition product N,N'-diphenylhydrazide-2-carboxy-5-methyl-4-hexenoic acid in sulphuric acid concentrated.

4-Prenyl-1,2-diphenyl-3,5-pyrazolidinedione (prenazone) in the medium of sulphuric acid concentrated (92-98%) undergoes an intramolecular rearrangement to 6',6'-dimethyl-4',5'-dihydropyrane-[2',3'-d]-1,2-diphenyl-3-pyrazolinone. The main decomposition product of prenazone, formed due to the hydrolytic process in the above conditions, undergoes changes according to two parallel reactions. First, it is hydrolyzed to prenylmalonic acid and hydrazobenzene which is subsequently transformed to benzidine. The second reaction proceeds via cyclization to form prenazone as well as 6',6-dimethyl-4',5'-dihydropyrane [2',3'-d]-1,2-diphenyl-3-pyrazolinone.