title: Structural elucidation of rabeprazole sodium photodegradation products.
abstract: Rabeprazole sodium is a proton pump inhibitor, used in acid-related disorders, like peptic ulcers and gastroesophageal reflux. It is known to be an acid-labile drug, however, few data about its stability under other factors are available. The aim of this work was to study the photodegradation of rabeprazole, to determine its kinetics and to elucidate the structures of the main degradation products. UVC-254 nm and metal-halide lamps were used. The analysis of the samples was carried out by HPLC. When the drug was in methanol solution, one main degradation product was formed; the degradation rate followed zero-order kinetics. The (1)H and (13)C NMR spectroscopic determinations revealed the product was the benzimidazolone. Another isolated product was identified as benzimidazole. The latter was confirmed against an authentic sample. A third photodegradation product was identified as the [4-(3-methoxy-propoxy)-3-methyl-pyridin-2-yl]methanol, by (1)H and (13)C NMR of the reaction mixture in chloroform-d. When powdered commercial tablets were exposed to UVC irradiation, they showed the same degradation products along with other unidentified, which appeared as traces; the degradation rate was slower than in solution. The intact tablets were stable after 50 days of exposition to the same light source.
authors.affiliation: Universidade Federal do Rio Grande do Sul, Programa de Pós-Graduação em Ciências Farmacêuticas, Faculdade de Farmácia. Av. Ipiranga, 2752 Lab. 402, Porto Alegre/RS, CEP 90610-000, Brazil. cassiavgarcia@yahoo.com.br
authors.forename: Cássia V
authors.initials: CV
authors.lastname: Garcia
authors.forename: Norma S
authors.initials: NS
authors.lastname: Nudelman
authors.forename: Martin
authors.initials: M
authors.lastname: Steppe
authors.forename: Elfrides E S
authors.initials: EE
authors.lastname: Schapoval
mesh_terms: D053799:2-Pyridinylmethylsulfinylbenzimidazoles / Q000737:chemistry* / Q000528:radiation effects*; D001562:Benzimidazoles / Q000737:chemistry; D002247:Carbon Isotopes; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003116:Color; D004340:Drug Contamination; D004355:Drug Stability; D006851:Hydrochloric Acid / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D000432:Methanol / Q000737:chemistry; D008968:Molecular Conformation; D011208:Powders; D011725:Pyridines / Q000737:chemistry; D064750:Rabeprazole; D012996:Solutions / Q000737:chemistry; D013237:Stereoisomerism; D013607:Tablets; D013696:Temperature; D013997:Time Factors; D014316:Tritium; D014466:Ultraviolet Rays
chemical_list: D053799:2-Pyridinylmethylsulfinylbenzimidazoles; D001562:Benzimidazoles; D002247:Carbon Isotopes; D011208:Powders; D011725:Pyridines; D012996:Solutions; D013607:Tablets; D014316:Tritium; C014353:benzimidazolone; D064750:Rabeprazole; D006861:Hydrogen Peroxide; C031000:benzimidazole; D006851:Hydrochloric Acid; D000432:Methanol