Ganta Madhusudhan Reddy

Synthesis of Metabolites and Related Substances of Rabeprazole, an Anti-Ulcerative Drug

Abstract Rabeprazole sodium (Aciphex®) is a gastric proton pump inhibitor used for the prevention and treatment of gastric acid–related diseases. During the synthesis of bulk drug of rabeprazole sodium, we have observed metabolites rabeprazole sulfide and rabeprazole sulfone and related substances rabeprazole-N-oxide, rabeprazole sulfone-N-oxide, N-aralkyl rabeprazole, chloro rabeprazole, and methoxy rabeprazole as impurities in the drug substance. The present work describes the synthesis and characterization of these compounds.

Synthesis and Characterization of Metabolites and Potential Impurities of Lansoprazole, an Antiulcerative Drug

Abstract Lansoprazole (Prevacid) is an antiulcerative drug used for the treatment of duodenal and gastric ulcers, reflux oesophagitis, and Zollinger–Ellison syndrome. During the bulk synthesis of lansoprazole, we have observed five impurities: lansoprazole N-oxide, lansoprazole sulfone N-oxide, lansoprazole sulfide, lansoprazole sulfone and N-aralkyl lansoprazole. The present work describes the synthesis and characterization of these impurities.

Practical synthesis of fingolimod from diethyl acetamidomalonate

A facile six-step synthesis of fingolimod, starting from readily available and inexpensive starting material diethyl acetamidomalonate, in very good yield is demonstrated.

Synthesis and Spectral Characterization of Related Substances of Vardenafil, an Erectile Dysfunction Drug

Abstract Vardenafil hydrochloride trihydrate (Levitra) is used to treat erectile dysfunction (ED) and is an inhibitor of phosphodiesterase type 5 (PDE-5) enzyme. It maintains higher levels of cyclic guanosine monophosphate (cGMP), relaxes smooth muscles, promotes penile blood flow, and enhances erectile function. During the bulk drug synthesis of vardenafil hydrochloride trihydrate, six related substances (impurities), vardenafil dimer, vardenafil N-oxide, vardenafil glycene, vardenafil oxopiperazine, vardenafil oxoacetic acid, and phenyl vardenafil were identified, and these are reported herein for the first time. The present work describes the synthesis and characterization of these impurities. GRAPHICAL ABSTRACT

Alternative Synthesis of Valganciclovir Hydrochloride

Abstract Synthesis of valganciclovir 1, a potent anticytomegalovirus (CMV) prodrug of ganciclovir 2, is described. The synthetic procedure involves protection–deprotection and reductive dehalogenation. GRAPHICAL ABSTRACT

Synthesis and Spectral Characterization of Related Substances of Lacidipine, an Antihypertensive Drug

Abstract Five related substances (impurities) were detected in lacidipine bulk drug substance by a simple high-performance liquid chromatographic method (HPLC) and were identified by liquid chromatography–mass spectrometry (LC-MS). These related substances were independently synthesized, characterized, and co-injected with the sample containing impurities.

Synthesis and Characterization of Metabolites and Potential Impurities of the Antiulcerative Drug Tenatoprazole

Abstract Tenatoprazole (Ulsacare®) is a recently developed antiulcerative drug used for the treatment of both erosive and nonerosive gastroesophageal reflux disease. During the bulk synthesis of tenatoprazole, we have observed four impurities (tenatoprazole N‐oxide, tenatoprazole sulfone N‐oxide, N‐methyl tenatoprazole, and desmethoxy tenatoprazole) and two metabolites (tenatoprazole sulfide and tenatoprazole sulfone). The present work describes the synthesis and characterization of these impurities.